An-Najah National University 

Faculty of Graduate Studies 

 

 
 

POLYMER WITH A DUAL ADSORPTION SITES: 

DESIGN, SYNTHESIS AND PURIFICATION OF 

POLLUTED WTAER FROM HEAVY METALS AND 

TOXIC ANIONS 

 

 

 

By 

Raneem Ahmad Abu Aysheh 

 

 

Supervisor 

Prof. Othman Hamed 

 
This Thesis is Submitted in Partial Fulfillment of the Requirements for the Degree of 

Master of Chemistry, Faculty of Graduate Studies, An-Najah National University, Nablus 

- Palestine. 

2023 



II 

 

 

 

 

 

 

 

 
POLYMER WITH A DUAL ADSORPTION SITES: DESIGN, SYNTHESIS AND 

PURIFICATION OF POLLUTED WTAER FROM HEAVY METALS AND 

TOXIC ANIONS 

 

By 

Raneem Ahmad Abu Aysheh 

 

This thesis was successfully defended on 3/ 4 /2023 and approved by 

   

Defense Committee Members                                                           Signature 

Prof. Othman Hamed / Supervisor                                      ……………………… 

Dr. Abdalhadi Deghles / Internal Examiner                       ……………………… 

Dr. Derar Smadi / External Examiner                                 ……………………… 

 

  



III 

Dedication 

To my loving dad and mom who support me to be the person that I always dreamed of. 

wishing them both long lives and good health. 

To my lovely husband, thank you for your greatest support. 

For my whole family. 

To my close friends who have supported me through every step of my life. 

I also dedicate this work to my creative doctors and professors who never failed to 

supply me with crucial information during my studies. 

To everyone who was in my life and is still doing so, I am grateful for your love and 

support. 

 

 

 

 

 

 

 

 

 

 

 

 

  



IV 

Acknowledgment 

The biggest and greatest thanks be to Allah, the Most Merciful, who led and guided me 

along the right way. 

I would particularly like to thank Professor Othman Hamed, who is my research 

supervisor, for allowing me to work with him. And for his direction and advice in 

obtaining quality research and good results. Additionally, I'd like to thank all of the 

professors and doctors who helped me earn my master's degree. 

I also appreciate my colleagues and friends especially, Angham, Reem, Jomana, Haneen 

and I am grateful for the days that brought us together. Finally, I would like to thank to 

Mr. Ameed Amireh, my supervisor in the chemistry lab, and all lab technicians at An-

Najah National University, for his assistance and support during this work. 

 

 

 

 

 

 

 

 

 

 

 

 

  



V 

Declaration 

I, the undersigned, declare that I submitted the thesis entitled: 

POLYMER WITH A DUAL ADSORPTION SITES: DESIGN, SYNTHESIS AND 

PURIFICATION OF POLLUTED WTAER FROM HEAVY METALS AND 

TOXIC ANIONS 

 

I declare that the work provided in this thesis, unless otherwise referenced, is the 

researcher’s own work, and has not been submitted elsewhere for any other degree or 

qualification. 

_____________________________________ Student's Name:  

_____________________________________ Signature: 

_____________________________________ Date: 

 

  



VI 

List of Contents 

Dedication ............................................................................................................................. III 

Acknowledgment ................................................................................................................. IV 

Declaration ............................................................................................................................. V 

List of Contents .................................................................................................................... VI 

List of Tables ....................................................................................................................... IX 

List of Figures ........................................................................................................................ X 

List of Schemes .................................................................................................................... XI 

List of Appendices .............................................................................................................. XII 

Abstract .............................................................................................................................. XIII 

Chapter One: Introduction ...................................................................................................... 1 

1.1 General Review ................................................................................................................. 1 

1.2 Wastewater purification and reuse .................................................................................... 3 

1.2.1 Polyzwitterions .............................................................................................................. 5 

1.2.2 Adsorption technique ..................................................................................................... 7 

1.2.3 Heavy and Toxic Metals ................................................................................................ 8 

1.2.3.1 Lead ............................................................................................................................ 9 

1.3 Cellulose ......................................................................................................................... 10 

1.3.1 Chemically modification of cellulose for heavy metals removal ................................ 13 

1.3.2 Cellulose as a metal adsorbent ..................................................................................... 21 

1.4 p-Phenylenediamine ........................................................................................................ 22 

1.5 Scope of This Study ........................................................................................................ 22 

Chapter Two: Experimental Part .......................................................................................... 24 

2.1 Materials ......................................................................................................................... 24 

2.2 Instruments ...................................................................................................................... 24 

2.3 Polymer synthesis ........................................................................................................... 24 

2.3.1 Activation of microcrystalline powder cellulose ......................................................... 24 

2.3.2 Oxidation of microcrystalline cellulose ....................................................................... 25 

2.3.2.1 Degree of substitution ............................................................................................... 25 

2.3.3 Crosslinking of cellulose 2,3-dialdehyde ..................................................................... 26 

2.3.3.1 Preparation of 2,3-cellulose diimine ......................................................................... 26 

2.3.3.2 Reduction of 2,3-cellulose diimine to 2,3-cellulose diamine ................................... 26 

2.3.4 Preparation of cellulose with zwitterionic functionality .............................................. 26 

2.4 Batch Adsorption Studies ............................................................................................... 27 



VII 

2.4.1 Calibration curves ........................................................................................................ 27 

2.4.2 Calibration curve for lead ............................................................................................ 27 

2.4.3 The influence of adsorbate (Pb²⁺) concentration on adsorption percentage ................ 28 

2.4.4 The influence of contact time on adsorption percentage ............................................. 28 

2.4.5 The influence of polymer dose on adsorption efficiency ............................................ 29 

2.4.6 The Influence of temperature on adsorption percentage ............................................. 29 

2.4.7 The influence of pH on adsorption percentage ............................................................ 29 

2.5 Adsorption isotherm ....................................................................................................... 29 

2.6 Adsorption kinetics ......................................................................................................... 30 

2.7 Adsorption Thermodynamic ........................................................................................... 31 

2.8 Wastewater Purification .................................................................................................. 32 

Chapter Three: Results and Discussion ................................................................................ 33 

3.1 Polymer Synthesis ........................................................................................................... 33 

3.1.1 Oxidation of cellulose to cellulose
-2,3-

diladehyde (Cell-Ald) ...................................... 33 

3.1.1.1 Degree of aldehyde substitution ............................................................................... 34 

3.1.1.2 Conformation of aldehyde presence by FT-IR ......................................................... 34 

3.1.2 Preparation of Cellulose crosslinked with Diamine .................................................... 36 

3.1.2.1 FT-IR of cellulose imine ........................................................................................... 37 

3.1.3 Conversion of Cellulose Diimine to a cellulose Diamine by Reduction ..................... 38 

3.1.3.1 FT-IR of cellulose diamine ....................................................................................... 40 

3.1.4 Preparation of Cellulose with Zwitterionic functionality ............................................ 40 

3.1.4.1 FT-IR of Cellulose based zwitterionic. ..................................................................... 42 

3.2.1 Adsorption of Lead Ions (Pb2+) .................................................................................. 43 

3.2.1.1 The influence of Pb2+ Initial Concentration ............................................................ 43 

3.2.1.2 Influence of contact time .......................................................................................... 45 

3.2.1.3 Influence of Adsorbent Dosage ................................................................................ 46 

3.2.1.4 Influence of Temperature .......................................................................................... 48 

3.3 Optimum adsorption parameters ..................................................................................... 50 

3.4 Adsorption analysis ......................................................................................................... 50 

3.4.1 Adsorption Isotherm .................................................................................................... 50 

3.4.1.1 Langmuir adsorption isotherm .................................................................................. 51 

3.4.1.2 Freundlich isotherm model ....................................................................................... 53 

3.4.2 Adsorption kinetics ...................................................................................................... 54 

3.4.2.1 Pseudo-first order model ........................................................................................... 54 

3.4.2.2 Pseudo-second order ................................................................................................. 55 



VIII 

3.4.2.3 Intra-particle diffusion Weber-Morris model ........................................................... 56 

3.4.2.4 Liquid film diffusion model ...................................................................................... 57 

3.4.3 Thermodynamics adsorption by Cell-X-ZWC polymer .............................................. 58 

3.5 Real wastewater purification from metals ...................................................................... 60 

3.6 Conclusion ...................................................................................................................... 61 

3.7 Recommendations ........................................................................................................... 61 

List of Abbreviations ............................................................................................................ 62 

References ............................................................................................................................. 64 

Appendices ............................................................................................................................ 82 

 ب‌ ..................................................................................................................................... الملخص

 

 

 

 

 

 

 

 

 

 

  



IX 

List of Tables 

Table 3.1: Effect of adsorbate concentrations on Pb²⁺ ions adsorption. ............................... 44 

Table 3.2: Effect of the contact time on Pb²⁺ ions adsorption. ............................................. 45 

Table 3.4: Effect of the temperature on the adsorption of  Pb²⁺ ions. ................................... 48 

Table 3.5: Effect of pH level on Pb²⁺ ions adsorption. ......................................................... 49 

Table 3.6: Optimum Adsorption Parameters for lead ions. .................................................. 50 

Table 3.7: Langmuir model values ....................................................................................... 52 

Table 3.8: Langmuir Adsorption isotherms parameters for Cell-X-ZWC ............................ 52 

Table 3.9: Freundlich model values ...................................................................................... 53 

Table 3.10: Freundlich Adsorption Isotherms parameters for Cell-X-ZWC. ....................... 54 

Table 3.11: Values of the pseudo-first order model. ............................................................ 82 

Table 3.12: Adsorption kinetic parameters for the adsorption of Pb²⁺ on Cell-X-ZWC 

(pseudo-first order model). ................................................................................ 82 

Table 3.13: Pseudo-second order model values .................................................................... 83 

Table 3.14: Adsorption kinetic parameters for the adsorption of Pb²⁺ on Cell-X-ZWC 

(pseudo-second order model) ............................................................................. 83 

Table 3.15: Intraparticle diffusion model values .................................................................. 83 

Table 3.17: liquid film diffusion model values ..................................................................... 84 

Table 3.18: Adsorption kinetic parameters (Liquid film diffusion model) for the 

adsorption of Pb²⁺ on Cell-X-ZWC. .................................................................. 84 

Table 3.19: Thermodynamic value for Van’t Hoff plots. ..................................................... 85 

Table 3.20: The Pb²⁺ adsorption on polymer thermodynamic parameters. .......................... 85 

Table 3.21: ICP-MS analysis results for toxic metal concentrations in the cell-X-ZWC 

polymer. ............................................................................................................. 86 

 

 

 

 

 

 

  



X 

List of Figures 

Figure 1.1: Model of a polyampholyte (left) and polyzwitterions on the (right) ..................... 6 

Figure 1.2: Examples on natural zwitterionic compounds .......................................................... 6 

Figure 1.5: Chemical structure of P-Phenylenediamine ............................................................ 22 

Figure 2.1: The Calibration curve for Pb²⁺ .................................................................................. 27 

Figure 3.1: FT-IR spectra of microcrystalline cellulose ............................................................ 35 

Figure 3.2: FT-IR spectra of cellulose after oxidation (Cellulose Dialdehyde) ..................... 36 

Figure 3.3: FT-IR spectra of Cellulose Diimine. ........................................................................ 38 

Figure 3.4: FT-IR Spectra of Cellulose crosslinking with amine. ........................................... 40 

Figure 3.5:  IR spectra of Cell-X-ZWC. ...................................................................................... 42 

Figure 3.6: (a) Effect of initial concentration of adsorbate on the Adsorption percentage 

of Pb²⁺, (b) Effect of initial adsorbate concentration on the adsorption 

capacity of Pb²⁺. ....................................................................................................... 87 

Figure 3.7: (a) Effect of contact time on the %Adsorption of Pb²⁺, (b) Effect of contact 

time on the adsorption capacity of Pb²⁺. ............................................................... 88 

Figure 3.8: (a) Effect of adsorbent dose on %removal of Pb²⁺, (b) Effect of adsorbent 

dose on %removal on the adsorption capacity of Pb²⁺. ...................................... 89 

Figure 3.9: (a) Effect of Temperature on the %removal of Pb²⁺,  (b) Effect of 

temperature on the removal capacity of Pb²⁺. ...................................................... 90 

Figure 3.10: (a) Effect of pH on the %removal of Pb²⁺ ions,  (b) Effect of pH on % 

capacity of Pb²⁺. ....................................................................................................... 91 

Figure 3.11: Langmuir model for adsorption of Pb²⁺ on Cell-X-ZWC. ............................... 92 

Figure 3.12: Freundlich model for adsorption of Pb²⁺ by Cell-X-ZWC. .............................. 92 

Figure 3.13: Model of pseudo-first order for Pb²⁺ absorption on Cell-X-ZWC. .................. 92 

Figure 3.14: Pb²⁺ absorption on Cell-X-ZWC: pseudo-second order model. ....................... 93 

Figure 3.15: Intraparticle diffusion model of Pb²⁺ adsorption by Cell-X-ZWC. .................. 93 

Figure 3.16: Model for the liquid film diffusion of Pb²⁺ adsorption on Cell-X-ZWC. ........ 93 

Figure 3.17: Van't Hoff diagram showing Pb²⁺ adsorption on Cell-X-ZWC. ...................... 94 

 

 

 

 



XI 

List of Schemes 

Scheme 1.1: (a)structure of modified cellulose NCC-PBG-A,(b) structure of modified 

cellulose NCC-PBG-B. .................................................................................... 15 

Scheme 1.2: (a) structure of Cell-AA, (b) Cell-AN, (c) Cell-GL ......................................... 17 

Scheme 1.3: Structure of  co-β-CMC-CD ............................................................................ 18 

Scheme 1.4: Structure of cell-p-PDA polymer. .................................................................... 19 

Scheme 1.5: Structure of cellulose amine polymer. ............................................................. 20 

Scheme 3.1: cellulose is transformed into cellulose-2,3-dialdehyde .................................... 33 

Scheme 3.2: oxidation of cellulose, reaction mechanism. .................................................... 34 

Scheme 3.3: The transformation of cellulose dialdehyde into cellulose diamine ................ 37 

Scheme 3.4: Reduction of Cellulose Diimine to cellulose Diamine ..................................... 39 

Scheme 3.5: Conversion of crosslinked Cell-Ald to cellulose based zwitterionic. .............. 41 

 

 

 

 

 

 

 

 

 

 

 

 

  



XII 

List of Appendices 

Appendix A: Tables .............................................................................................................. 82 

Appendix B: Figures ............................................................................................................. 87 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  



XIII 

POLYMER WITH A DUAL ADSORPTION SITES: DESIGN, SYNTHESIS AND 

PURIFICATION OF POLLUTED WTAER FROM HEAVY METALS AND 

TOXIC ANIONS 

By 

Raneem Ahmad Abu Aysheh 

Supervisor 

Prof. Othman Hamed 

 

Abstract 

Demand for clean is increasing due to the increase in population.  Recycling of 

contaminated wastewater could be an answer for this issue.  Wastewater is 

contaminated with a  variety of toxic materials depending on the contamination source.  

The pollutants mainly include metal ions and organic matters that are released from 

various sources such as medical, plumbing, agricultural, body care products, household 

chemicals,  and industries. Among the toxic heavy metals that raise a serious concern 

are Cr²⁺, Pb²⁺, Hg²⁺, Cd²⁺, and others that are harmful to creatures.  

To remove hazardous heavy metals' pollutants and enhance water quality, researchers 

used various adsorbent that are polymer based. Modifying existing polymers could be 

the simplest and most effective way to generate a low-cost adsorbent with high 

efficiency against metals and hazardous organic compounds. 

Among all developed techniques, the adsorption removing approach has attracted the 

most attention. It has been particularly interesting to develop a superior   adsorbent 

demonstrating a high adsorption capacity and low cost for removing various pollutants 

from contaminated waters. This study aims to develop cellulose with multi coordination 

site and zwitterionic functionality.  

This study was planned to generate cellulose with multi coordination site and 

zwitterionic functionality. These criteria make it superior adsorbent for application in 

purification of polluted wastewater. 

The target cellulose was designed to have coordination sites for toxic heavy metals and 

toxic anions such as nitrate. The method of making the polymer comprises three steps: 



XIV 

the first step involves adding an aldehyde functionality to cellulose powder by oxidation 

(Cell-Ald). In the second step Cell-Ald was crosslinked with a polyamine such 1,4-

pheneylendiamine (PPD) to produce a 3D structure with multi coordination site, which 

then will be reacted with 1,4-butane sultone to form the target polymer cellulose with 

zwitterionic functionality (Cell-3D-ZWI). The polymer structure was confirmed by FT-

IR.  

The polymer was evaluated for their ability to adsorb Pb²⁺ ions. The percentage of metal 

adsorption was investigated as a function of Temperature, pH, adsorbent dosage, contact 

time, and initial concentration of metal ions. The high efficiency in adsorbing heavy 

metals from wastewater, with the maximum adsorption result for Pb²⁺ being 97.43% at 

pH ≈7.21, adsorbent dosage =20 mg, initial concertation of metal ion =10 ppm, contact 

time =20 min and temperature =20°C.  

In addition, the adsorption isotherm, kinetics, and thermodynamics were measured. The 

thermodynamic parameters of Pb²⁺ adsorption is spontaneous (ΔG°<0), exothermic 

process (ΔH°<0) and the reaction occurs spontaneously at low temperatures (ΔS°<0). 

All adsorption processes follow the pseudo- second order adsorption kinetics model 

(R²= 0.99), which was established by the adsorption parameters, and these adsorptions 

were matched with the Freundlich isotherm of adsorption (R²=0.89). 

The target compound was prepared and identified by IR spectroscopy, it has good 

thermal stability, it adsorbed metals from wastewater at high efficiency. 

Keywords: Cellulose, Water pollution, Wastewater treatment, Heavy metal, Lead, p-

Phenylenediamine, 1,4-butane sultone, Zwitterions. 



1 

Chapter One 

 Introduction 

1.1 General Review 

One of life's most basic requirements is water. In the world, there are 0.3% of useable 

water resources [1]. Water is necessary for human survival and well-being and is 

significant to many economic sectors, also it is essential for sustainable ecosystem 

services. Water is one of the most convenient natural resources, because it is capable of 

recycling, storing, transporting and diverting [2].  

However, due to human activity and economic growth, water resources are unevenly 

distributed in both geography and time, and they are under pressure and stress [3, 4]. 

There is significant water stress in many nations as a result of the negative effects of the 

global population growth, the implications of climate change, and changes in lifestyle 

[1].  

In addition to severely reducing water supply per person, population growth and rising 

water demand would put pressure on biodiversity across the entire world environment. 

In addition to temperature, rainfall, evaporation rates, vegetation type, and water 

overflow are other significant elements that affect water availability. Additionally, there 

are currently significant challenges to fairly distributing the world's freshwater 

resources among and between nations [5]. 

A healthy environment, clean air, and pure water are becoming more and more rare [6]. 

Recent decades have seen a decline in water quality due to population growth, fast 

industrialization, and careless use of natural resources. Also among the major pollutants 

to be concerned about are organic matter, food, pharmaceuticals, personal care items, 

heavy metals, pigments, and plastics [7, 8]. 

Pollution occurs through the introduction of contaminants into the natural system. More 

than 200 million people on earth are harmed by toxic substances that are present as 

pollutants. 80% of diseases, as posted by the World Health Organization (WHO), are 

transmitted by water [9].  



2 

When harmful foreign elements enter the water stream, such as agricultural chemicals, 

pesticides, and fertilizers, or metals like lead or mercury, water pollution occurs [10]. In 

addition to reducing usage and drinking water, water pollution also destroys the lives of 

all aquatic life and reduces the biological diversity of the ocean, sea, lake, and aquatic 

ecosystems [1, 11]. 

Heavy metals have received the most attention from environmental scientists among all 

pollutants because of their hazardous nature. Natural water often contains minimal 

levels of heavy metals, but many of them are dangerous even at extremely low doses 

[12, 13].  

Heavy metal contamination, such as that brought on by Lead (Pb), zinc (Zn),  mercury 

(Hg), nickel (Ni), arsenic (As), copper (Cu), chromium (Cr), and cadmium (Cd) has 

recently received much interest because of their toxicity to human, environment and 

other creatures [14-16].  

They are mostly produced in the medical, agricultural, plumbing, domestic, personal 

care, textile, tannery, and manufacturing industries [17, 18]. 

Heavy metals are hazardous due to their bioaccumulation, which is defined as an 

increase in chemical concentrations in a biological organism over time relative to 

environmental chemical concentrations. As previously indicated, heavy metal ions are 

not biodegradable. They can influence a variety of organisms directly or indirectly due 

to biomagnification, and they are stable. They can cause a serious health problems 

including nervous system diseases, cancer, organs damage (lungs, kidneys, liver, 

esophagus, stomach) and skin, even when they are only present in minute amounts [19-

23]. 

The threshold limit value (TLVs) of toxicity, which is known as the average 

concentration toxic substance concertation in air in which a normal person may be 

exposed to for 8 h/week for their life time without feeling any negative effects, is related 

to the inhalation toxicity [24].  

When the concentration of a heavy metal in water surpasses a certain level, it is 

considered a pollutant and harms living organisms. Based on its toxicity, each 

hazardous metal has a threshold limit value [13, 25].  



3 

Chronic exposure to hazardous metals has negative effects that become noticeable after 

a period. Cadmium causes cerebrovascular infarction, cardiac failure cancers,  lung 

cancer, osteoporosis and emphysema [26, 27].  

Copper can cause capillary damage, renal damage, hepatic, irritation and depression, of 

the central nervous system are all carried on by copper [28, 29]. Mercury damages the 

nervous system, the kidneys, and induces mutagenesis [30].  

Zinc has been associated to prostate cancer, kidney failure,  icterus, anemia and liver 

failure [31]. Also, Anemia, anorexia, vomiting, liver and lung damage, loss of appetite, 

damage to the digestive and urinary systems, harm to the developing fetal brain, and 

degradation of the nervous and circulatory systems can all result from lead poisoning 

[32, 33].  

As a result, it became important to remove toxic metals from water because they disturb 

human organelles and are non-biodegradable pollutants that are consumed through the 

food chain [34]. 

1.2 Wastewater purification and reuse 

It is essential to have access to clean drinking water since contamination not only 

reduces the amount of freshwater that can be used, but also has an effect on both human 

health and the ecosystem [35]. 

The most crucial component for survival is water, which is composed of two hydrogen 

atoms connected by an oxygen atom. A variety of contaminants, including dangerous 

compounds used in human activities, naturally occurring minerals and chemicals, and 

contaminants that alter flavor, smell, and color, among others, could pollute it. In order 

for water to be appropriate for its intended application, contaminants must be removed 

or reduced through treatment. Making water suitable and acceptable is the process of 

water treatment [36]. 

The ability to treat and reuse water provides advantages that serve as the primary 

motivations for developing reuse programs. These advantages include increased 

agricultural production, less energy use for water production, treatment, and 



4 

distribution, and major environmental advantages like decreased nutrient loads to 

receiving waters due to the reuse of treated wastewater [37].  

As a result, water purification has become a global crisis that must be resolved in order 

to maintain ecological stability and improve public health. To solve this issue, finding 

effective water treatment systems that are high-performing, affordable, and energy-

efficient is very important. The literature reports a number of methods for removing 

harmful heavy metals from wastewater.  

The most efficient of these are adsorption and precipitation [38]. The most 

consideration was given to the adsorption method because it is both highly efficient and 

inexpensive [39].  

For commercial application, ideal adsorbents should have the following characteristics; 

Large adsorption capacity, high adsorption rate, cost-effectiveness, environmental 

safety, easy of separation, robustness, and reusability [40].  

One of the most studied adsorbents for the removal of metals from wastewater is 

activated carbon; nevertheless, the high costs associated with material processing have 

made it less desirable in some situations [41].  

Naturally produced materials like clay [42], zeolites [43], and peats [44], were also 

investigated as toxic metal adsorbents. industrial residue that includes fly ash, sludge, 

red mud, and metal hydroxide [45]. 

As a consequence, it has been proposed that inexpensive, environmentally friendly 

adsorbents made from agricultural waste would make good alternatives for treating 

wastewater [46, 47]. 

 Among the natural based adsorbents that received the highest attention are cellulose, 

lignin, chitosan and hemicellulose. Cellulosic based adsorbents specially those obtained 

from waste form Kenaf waste [48], cotton [49], wheat [50], sawdust of wood [51], husk 

form rice [52] were already evaluated as adsorbents of various metal ions such as Cd
2+

, 

Co
2+

, Cu
2+

, Mg
2+

, Sr
2+

, Al
3+

, Ni
2+

, Mn
2+

,  Cr
3+

, Zn
2+

and Pb
2+ 

ions. 



5 

 However, they may be produced significantly more cheaply than activated carbon, 

despite having a lower adsorption capacity due to its larger surface area. They are 

particularly effective at removing heavy metal ions from wastewater while being 

ecologically friendly and economically feasible [53]. In recent years, a breakthrough 

was made in polymeric nanotechnology for generating promising nanomaterials as an 

adsorbent for toxic metals. Among these is cellulose nanocrystals (CNCs), which is 

unique regarding functionality, high surface and rigidity, which resulted in improved 

purification efficiency. Despite the significant development in nanocellulose adsorbents, 

several nanocellulose derivatives have still not been investigated as metal adsorbents 

[54].  

1.2.1 Polyzwitterions 

Recently, several innovative ideas have been published in the literature for the 

instantaneous removal of heavy metal ions from polluted water using cellulose with 

zwitterionic functionality as the adsorbent [55-60].  

Zwitterions have both positively and negatively charged group as a pendent-side 

groups. Polyzwitterions material bear on their repeat units equal number of anionic and 

cationic groups [61]. This type of material represents a special type of  polyampholytes 

presenting a very specific properties [62-65]. In these types of materials, the ionic 

groups are efficient over a wide range of pH values.  

So, both charges positive and negative are present on the repeat unit, the total charge of 

polyzwitterions is zero, yet there is no association between them Figure1.1 [62-66]. 

They are used as ionomers in food waring applications [67-70], in fibers due to strong 

interactions they form with the dye stuffs [71-73]. Due to their high tolerance to saline 

environments, they are used as a rheology modifier [74, 75]. 

 

 

 

 



6 

Figure 1.1 

 model of a polyampholyte (left) and polyzwitterions on the (right) 

 

Note. The image was created to represent model of a polyampholyte and polyzwitterions. “by Biehl, P., et 

al., Synthesis, characterization, and applications of magnetic nanoparticles featuring polyzwitterionic 

coatings. 2018. 10(1): p. 91.” [76]. 

Examples on natural zwitterionic compounds are shown in Figure 1.2 From left to 

right: phospholipid 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine (DMPC), 

trigonelline, ectoine, betaine, 3-dimethylsulfoniopropionate (DMSP), arsenobetaine [77-

79]. 

Figure 1.2 

 Examples on natural zwitterionic compounds 

 

Note. The image was created to represent natural zwitterionic compounds. “by Laschewsky, A.J.P., 

Structures and synthesis of zwitterionic polymers. 2014. 6(5): p. 1544-1601.” [71] 

The presence of such functionality structure allows the adsorption and recovery of 

heavy metal ions from wastewater by the electrostatic effect [80-82]. The main cause 

for the lack of a wider use of this methodology is the complexity of synthesizing a 

cellulose-based adsorbent with a high degree of substitution of with zwitterionic 

functionality. Therefore, it is necessary to design and synthesize a cellulose-based 

adsorbent with a high degree of substitution of amino and sulfonate groups in order to 

create adsorbent with high efficiency for anionic and cationic heavy metals.  

Therefore, this research, offers a cellulose-based adsorbent with high degree of pendant 

groups composed of ammonium, amine and sulfonate, presence of these groups on same 

repeat unit create coordination sites for metal and zwitterion functionality.  



7 

The target cellulose based-zwitterionic will be synthesis by oxidation then crosslinking 

of cellulose then reacting with 1,4-butane sultone. This target polymer will be evaluated 

as an adsorbent for Pb²⁺ under various adsorption conditions. The mechanism of 

adsorption of adsorbents for the metal removal of the target ions from an aqueous 

medium will be also studied. 

1.2.2 Adsorption technique 

Heavy metal pollution of water is a serious issue because of the harmful effects that 

heavy metals have on the environment and on living creatures, particularly because of 

their tendency to bioaccumulate and persistence in nature. Adsorption technologies are 

one technique that has been developed recently to purify natural water from heavy 

metals and industrial waste. Conventional adsorbents, such activated carbon, sometimes 

produce hazardous sludge that needs to be post-treated while also being less effective. 

Although nanotechnology adsorbents have recently been employed in water 

purification, their practical applications in the removal of hazardous heavy metals are 

limited because of the complicated synthesis procedure and high cost [83].  

A suitable adsorbent for the removal of heavy metals should have a low cost, stability, 

ease of separation, simplicity of design, high absorptivity, high adsorption capacity, and 

good reusability [84, 85].  

Adsorptions take place when an adsorbate leaves the liquid phase of the contaminated 

mixture and bond to the adsorbent surface through a physical or chemical interaction. 

According to adsorption science, the material that is adsorbed on the solid surface is 

known as an adsorbate, while the solid surface is known as adsorbent. Adsorbate can be 

dissolved solids, a gas, or a liquid. While adsorbent can be either a liquid or a solid [86]. 

Adsorption technique efficiency is influenced by several variables. These factors 

include the adsorbent's surface area, activation energy, as well as the type of adsorbent 

and adsorbate. It also depends on the conditions of the experiment. such temperature, 

pressure, and pH level [87]. 

New intermolecular forces of attraction are created between the adsorbent and the 

adsorbate as a result of this purification process. Two categories of adsorption can be 

distinguished based on the nature of these forces. 



8 

1. Physical Adsorption (Physisorption) 

This kind of adsorption has a wide range of features. These are dipolar interactions, 

which are weak intermolecular forces of bonding. Physical type of adsorption also 

requires very little activation energy because it has a lower heat of adsorption. Since 

it is not highly selective, physisorption creates multi-molecular layers [88].  

Additionally, this type of adsorption is reversible since the adsorbate molecule is 

free to roam around the adsorbent surface instead of being fixed in one place. This 

allows for the possibility of adsorbate recovery [88]. 

Physisorption frequently takes place with no heat and is readily reversible by raising 

the temperature or lowering the pressure [89]. 

2. Chemical Adsorption (Chemisorption) 

The following are some of chemisorption's characteristics: Chemical bonds, like 

covalent and ionic bonds, are strong forces of interaction. Additionally, it has a 

relatively high adsorption enthalpy, which means that this adsorption typically needs 

a high activation energy to occur [90].  Furthermore, chemisorption is irreversible, 

specific, and occurs at high temperatures [91]. 

1.2.3 Heavy and Toxic Metals 

Metals that are "bad" for the environment are referred to as "heavy transition metals." 

Based on the atomic weight, atomic number, density, or other characteristics of the 

elements or their compounds, it might indicate a variety of things [92]. 

 Metals with an atomic number (Z) more than 20 and an elemental density greater than 

5.0 g/cm
3 

are classified as heavy metals. The 51 elements of the periodic table are 

categorized by scientists as heavy metals based on this classification. Three groups of 

heavy metals are distinguished: radionuclides, precious metals, and toxic metals [93, 

94]. 

Heavy metals, in contrast to organic-based contaminants, cannot be biodegraded once 

they are released into the environment. For the rest of their lives, they will keep harming 

the environment, water, and air. Reduced metal toxicity, mobility, and bioavailability 

are the fundamental methods for reducing pollution. While some trace amounts of 



9 

transition heavy metals are necessary, the vast majority are toxic to all living things 

[95]. 

Five main factors contribute to the presence of heavy metals in aquatic systems: 

geological weathering, industrial processing, utilization of metals compounds and 

metal`, combustion of fossil fuels, and metal leaching from rubbish and solid trash 

dumps. Lead, cadmium, mercury, and arsenic are the heavy metals that have the greatest 

negative effects on human health. International institutions like the World Health 

Organization regularly monitor the effects of these metals on human health as a result of 

extensive research on them. Humanity has been using heavy metals for a very long time. 

Heavy metal exposure is still present and even increasing in some parts of the world, 

primarily in developing nations, despite the fact that heavy metal pollution has declined 

over the past 100 years in the majority of developed nations [96]. 

In general, a variety of factors affect the toxicity of heavy metals. These include age, 

speciation, total dose absorbed, and exposure route. Large doses of any heavy metal 

may result in either chronic toxicity with a long-term effect or acute toxicity with a 

short-term effect. Some heavy metals may be hazardous in higher concentrations even 

though they are innocuous or even vital for life at trace amounts. This is true, for 

example, with copper and zinc, which necessary in trace amounts for living things, have 

poisonous consequences when present in higher concentrations. The toxicity of a heavy 

metal is inversely associated with its TLV, meaning that metals with lower TLVs will 

be more poisonous than those with higher TLVs [97, 98]. 

1.2.3.1 Lead 

A naturally occurring element, has a density that is higher than the bulk of other 

materials. Freshly cut lead has a silvery appearance with a trace of blue, but when it is 

exposed to air, it oxidizes and turns dark gray. Among all stable elements, lead has the 

highest atomic number. It is not very reactive, and when its oxides come into contact 

with acids and bases, they form covalent bonds [99].  

Typically, lead compounds are found in the +2 oxidation state , rather than the +4 

oxidation state that is common for lighter carbon group members. It was used in many 

different industries, including electroplating, metallurgy, chemicals, and many more. 



10 

Hazardous heavy metal lead can harm your bones, brain, blood, kidneys, thyroid glands, 

and other organs. The discharge's toxic nature and presence of lead have additional 

negative effects, also at extremely low levels. Lead metal levels in water might be 

dangerous [99]. 

 Pb²⁺ released into the environment eventually is transported to human organs through 

the food chain or drinking water. As a result, there may be danger to the neurological, 

hematologic, and reproductive systems of humans [100].  

Lead is a toxic chemical that accumulates in bones and soft tissues, harming the 

neurological system. Even if blood levels are quickly restored with treatment, 

neurological disorders like brain damage can still happen [99].  

Finally, there are other lead sources that can result in lead poisoning, including lead 

paint, lead-contaminated household dust, soil, water, and food. All sources of lead 

should be controlled or eliminated because lead accumulates in the body [100]. 

1.3 Cellulose 

The most abundant and renewable biopolymer on earth is cellulose. The formula for this 

organic polymer is (C6H10O5)n. The homopolysaccharide molecular structure of 

cellulose is a linear polymeric chain of thousands of  the monomer D-

anhydroglucopyranose joined by – a glycosidic linkages. The chair shape of the six-

membered heterocyclic -D-anhydroglucopyranose is the most common form [101]. 

 

 

 

 

 

 

 

 



11 

Figure 1.3  

Molecular structure of cellulose polymer  

 

Note. The image was created to represent molecular structure of cellulose polymer. “by Eyley, S. and 

W.J.N. Thielemans, Surface modification of cellulose nanocrystals. 2014. 6(14): p. 7764-7779.” [102]. 

The many hydroxyl groups found in cellulose can be broken down into three groups: the 

primary hydroxyl group is C-6, while the secondary hydroxyl groups are C-2 and C-3 

[103].  

These numerous hydroxyl groups form hydrogen bonds with oxygen atoms near or 

inside the same backbone (intra molecule hydrogen bonding), causing the chain to come 

into touch with one another and producing microfibrils with a high tensile strength. 

Heavy metal ions have an affinity for hydroxyl groups [103]. 

 

  



12 

Figure 1.4 

Molecular structure of cellulose polymer showing H-Bonding 

 

 

 

Note. The image was created to represent H-Bonding in molecular structure of cellulose polymer. “by 

Baghaei, B. and M.J.M. Skrifvars, All-cellulose composites: A review of recent studies on structure, 

properties and applications. 2020. 25(12): p. 2836.” [104] 

Cellulose has a molar mass of 162.1406 g/mol per glucose unit, a density of 1.5 g/cm
3
, a 

melting point of 260–270  , is biodegradable, and has hydrophilic regions that make it 

insoluble in water and most organic solvents [105]. In nature, cellulose is present in a 

wide range of creatures, including plants, bacteria, fungi, invertebrates, amoebas, 

minerals, and many marine organisms.  

However, the primary source of cellulose is plant fiber. Most organisms have cellulose 

as a structural element of their cell walls. To form porous biofilms, certain bacteria also 

excrete bacterial cellulose. 1011–1012 tons of relatively pure cellulose are 

manufactured each year. Cellulose makes up 90.0% of cotton, and a dried hump 

contains roughly 57.0% of it [106]. 

The number of repeat units (DP), which denotes the number of repeating monomers, is 

represented by the number n in the chemical formula for cellulose (C6H10O5)n. The 

degree of polymerization affects a number of cellulose properties (chain length). In 

plant cells, cellulose has a DP of roughly 15000 units and about 10,000 units in wood. 

Mechanical strength and melting temperature rise as DP rises [107]. 

There are crystalline and amorphous areas in cellulose fibrils. The cellulose crystalline 

structure has an impact on cellulose properties. For instance, As the proportion of 



13 

crystalline rises, the cellulose's strong and tightly packed hydrogen bonding network 

causes the amorphous fraction to become less flexible. Numerous cellulose amorphous 

result from the wide orientation of the hydrogen bonding networks [108]. 

 Flexible cellulose nanofibrils are produced through enzymatic or chemical oxidation of 

cellulose fibrils. Short rigid cellulose nanocrystals will be produced if amorphous 

regions hydrolyze with a strong acid (few nm in length). This substance possesses a lot 

of useful qualities [108]. 

Since it is readily available, nontoxic, chemically, and thermally stable, biodegradable, 

and has a high tensile and compressive strength, cellulose is an excellent choice for 

adsorbing metals. The linear, long chain of cellulose polymer is filled with many 

hydroxyl groups that extend from the chain and produce intermolecular hydrogen 

bonds, which improve the interaction of neighboring cellulose molecules. If the 

hydroxyl groups are changed, many derivatives of cellulose can be produced and 

employed in an infinite number of applications [109]. 

1.3.1 Chemically modification of cellulose for heavy metals removal 

When cellulose is chemically modified, the hydrogen bonds are broken, the crystal 

structure is reduced, and more efficient binding sites (OH groups that are more 

attackable by other functional groups and enhance adsorption) are generated [103]. 

The two main techniques for cellulose modification are: 

1) The formation of a cross-linking network (gel) through chemical bonding of the OH 

and NH2 groups, which is insoluble in water. 

2) Creating hybrid materials by using grafting reaction to control polysaccharide 

movement on a surface [110]. 

Various cellulose polymers that have been chemically modified were developed and 

used in the purification of water. Cellulose was obtained from the solid part waste 

produced by the olive industry to produce the polymers (NCC-PBG-A and NCC-PBG-

B) Scheme 1.1 [108].   

The first polymer NCC-PBG-A, which contains both groups amine and  imine, was 

produced by first oxidizing the isolated cellulose and then reacting it with 



14 

phenylbiguanide. Then, a borohydride (BH4) was used to reduce the imine groups to 

produce a new polymer NCC-PBG-B that was loaded with amine functionality. The 

polymers were examined for their ability to remove Cu²⁺ and Pb²⁺ ions from sewage. 

With regard to these ions, both polymers showed higher adsorption effectiveness [111]. 

 

 

 

 

 

  



15 

Scheme 1.1 

(a)structure of modified cellulose NCC-PBG-A,(b) structure of modified cellulose NCC-

PBG-B 

 

 

 

 

 

 

 

 

(a) 

(b) 

Note. The image was created to represent structure of modified cellulose NCC-PBG-A and NCC-PBG-B. 

“by Peng, B.L., et al., Chemistry and applications of nanocrystalline cellulose and its derivatives: a 

nanotechnology perspective. 2011. 89(5): p. 1191-1206.” [108]. 

Researchers developed, manufactured, and evaluated multidentate chelating cellulose 

polymers with excellent efficacy for toxic metal ions in water. The synthesis involved 

reacting microcrystalline cellulose (Cell-AA), which was taken from the solid waste of 

the olive industry, with tert-Butyl acetoacetate.  



16 

This formed cellulose with  -ketoester functionality, which was then reacted with 

aniline and the amino acid glycine to produce Cell-AN and Cell-GL, respectively.The 

Cell-AA and Cell-GL polymers had the highest Pb²⁺ efficiency at concentrations of 10.0 

ppm, 50.0 mg at 9.0 pH and at 30 °C after being shaken for 120 minutes. At almost the 

same prior conditions, the Cell-AN polymer showed the best efficiency toward Pb²⁺ at 

86.7% Scheme 1.2 [112]. 

  



17 

Scheme 1.2 

(a) structure of Cell-AA, (b) Cell-AN, (c) Cell-GL 

 

(a) 

 

 

(b) 

 

(c) 

Note. The image was created to represent structure of Cell-AA, Cell-AN and Cell-GL. “by Nairat, N., et 

al., Cellulose polymers with β-amino ester pendant group: design, synthesis, molecular docking and 

application in adsorption of toxic metals from wastewater. 2022. 16(1): p. 1-21.” [112] 



18 

Cellulose was used as one of the main ingredients in a three dimensional crosslinked 

polymer that was used to remove dangerous metals from water. Carboxymethyl 

cellulose (CMC) was first made by combining cellulose with chloroacetate and a 

solution of sodium hydroxide in isopropyl alcohol.  

At approximately 160 °C,  -cyclodextrin and the generated CMC were crosslinked. 

Three crosslinked cellulose and cyclodextrin polymers (co- - CMC- CD) A, B, and C 

were synthesized and manufactured. When synthesizing the polymers, various ratios of 

the materials were used [113].  

The ability of the three polymers to remove Pb²⁺ from a water solution was investigated. 

At pH 7.5, 20°C, and 0.05 mg/L concentration, the maximum adsorption efficiency was 

achieved. Compared to the other two polymers, Polymer B had a lower efficiency 

toward Pb²⁺.  

The outcomes also indicate that Pb²⁺ adsorption takes place on the surfaces of polymer 

A in a pseudo-second-order model. The adsorption process  G  value was negative, 

according to thermodynamic experiments, suggesting a spontaneous adsorption process 

[113]. 

Scheme 1.3 

Structure of  co-β-CMC-CD 

 

Note. The image was created to represent structure of  co-β-CMC-CD. “by غ‌  Anionic ,ابتهال and .شقذان,

Microcrystalline Cellulose For Removal of Pb+ 2 From Waste Water Purification. 2020, ‌ ‌النجاح جامعة

 .[113] ”.الوطنية



19 

Novel adsorbent based on cellulose was created by functionalization of Nanocrystalline 

Cellulose (NCC) to make it a potential novel metal ion adsorbent. The cellulose used in 

this study derived from olive industry solid waste (OISW), which was hydrolyzed into 

nanocrystalline form, then oxidized to cellulose dialdehyde (CDA), which was then 

reacted with 1,4-phenyldiamine under mild conditions to produce the final cellulose 

diamine (cell-p-PDA) product Scheme 1.4 [114].  

The produced cell-p-PDA was examined as an adsorbent of the metal ions Pb²⁺and Cu²⁺ 

from wastewater, and at a pH value of  8.3 and at room temperature, it displayed 

excellent eficiency toward both metals. Additionally, an actual sample of sewage 

containing more than 20 elements was successfully processed by Cell-p-PDA. The 

different functionalities on the polymer surface and the potential semi-crown ether 

structure produced by cross-linking the cellulose chain with 1,4-phenylene diamine may 

be responsible for the excellent extraction efficiency of the cell-p-PDA polymer.  

According to the kinetic analysis, the metal ion adsorption by cell-p-PDA was pseudo-

second order and followed the Langmuir isotherm model [114]. 

Scheme 1.4 

Structure of cell-p-PDA polymer 

 

Note. The image was created to represent structure of cell-p-PDA polymer. “by Hamed, O., et al., 

Synthesis of a cross-linked cellulose-based amine polymer and its application in wastewater purification. 

2019. 26: p. 28080-28091.” [114]. 

 



20 

A new cellulose amine polymer was synthesized using a three-step technique using 

cellulose and o-phenylenediamine as a chelating agent. In this procedure, cellulose is 

first converted using aldehyde, then to imine, and that was reduced to amine by sodium 

borohydride. 

 As seen in Scheme 1.5, this cellulose derivative has several coordination sites. In a 

sewage sample, the cellulose polymer with the amine moiety served as a new adsorbent 

for toxic metal ions like Fe³⁺, Pb²⁺and others[115]  

The high efficiency was associated with the presance of many functional groups such as 

hydroxyl, ether, aromatic, and amine. The effectiveness of the cellulose amine polymer's 

adsorption on Fe
3⁺

 and Pb²⁺ was examined. According to kinetic studies, the adsorption 

isotherm corresponds to the Langmuir isotherm model [115].  

Scheme 1.5 

Structure of cellulose amine polymer 

 

Note. The image was created to represent structure of cellulose amine polymer. “by Deghles, A., et al., 

Cellulose with bidentate chelating functionality: an adsorbent for metal ions from wastewater. 2019. 

14(3): p. 6247-6266.” [115] 

First, cellulose with dialdehyde groups was generated from cellulose that had been 

extracted from the solid waste of the olive oil industry by oxidation with sodium 

periodate, followed by a reaction with p-diaminobenzene to create cellulose imine, 

which was subsequently hydrognetaed to cellulose diamine by a reaction with sodium 

borohydride. Prepared cellulose diamine has a distinctive molecular structure; the 

diamine molecule binds the cellulose chains to generate a type of crown amine [116].  



21 

The nitrogen and oxygen binding sites in the crown amine cages are distributed around 

the ring. These locations show a particularly strong metal affinity. Toxic elements from 

wastewater were removed using the produced cellulose diamine. The optimal conditions 

were a temperature of 30  , a time about 120.0 min, a pH about 4, and a dosage of 0.50 

g. The results generated by kinetic study demonstrated that the rate of adsorption 

follows a pseudo-second-order [116]. 

In another study, cellulose powder was utilized to produce magnetic cellulose 

nanocrystalline (MNCs), which had been used as selective magnetic adsorbents to 

remove methylene blue from water. In this study, OISW was utilized to make the 

cellulose powder [46].  

By using acid hydrolysis, the extracted cellulose was converted into NCs. NCs were 

treated with a solution of FeSO4, FeCl3.6H2O, and H2O in order to produce MNCs using 

the colloidal suspension method. For inorganic nanoparticles from aqueous solutions, 

MNCs act as an efficient, economical, and rapid adsorbent. According to 

thermodynamic analyses, the adsorption process occurs spontaneously at different 

temperatures [46]. 

1.3.2 Cellulose as a metal adsorbent 

Because of increased urbanization, population expansion, and economic development, 

there is an increase in the amount of produced wastewater and its overall pollutant load 

globally. Our primary objective in developing this work was to create a novel practical 

method of extracting heavy metals using cellulose-based materials as adsorbents. 

Wastewater needs to be cleaned up, with a heavy metal elimination goal in mind [117]. 

There are a number of widely used techniques for heavy metal removal from water, but 

these techniques have some limitations. The most simple, sustainable, and effective 

technology for wastewater purification was adsorption. As a result, efforts were directed 

on using inexpensive adsorbents. Due to its crystallinity and hydrogen bonding, 

cellulose is a natural, recyclable, biodegradable, non-meltable, and insoluble in most 

solvents. Cellulose is a good metal adsorbent that is easily chemically modified. 

because cellulose has a lower adsorption capacity for heavy metals [118, 119]. 



22 

1.4 p-Phenylenediamine 

p-Phenylenediamine is an organic compound with The molecular formula is 

C6H4(NH2)2 while the molar mass is 108.1 g /mol [120]. This aniline derivative is a 

white solid, however samples may turn darker as a result of oxidation in the air. In 

engineering polymers and composites like kevlar, it is mostly used as a constituent. It is 

also a component of hair dyes, and it is sometimes used in henna [121].  

Poly phenylenediamine , a less expensive diamine derivative of polyaniline (PANI), has 

also attracted attention and that was related to its high oxidative polymerization and 

large number of imine and amine groups. A lot of interest has been given to poly 

phenylenediamines because they contain both cationic and redox characteristics [122].  

Due to their numerous applications, high electroactivities, and high thermal stability, 

aromatic amine polymers have recently been receiving a lot of attention. As a result of 

oxidation reduction reactions and chelations property of the amino and imino groups, 

PPDs have demonstrated a strong affinity for metal ions. PPD with plenty of amine 

groups can reduce the valence states of absorbing metallic pollutants by acting as 

electron donors [122]. The structural formula of PPD is shown in Figure 1.5. 

Figure 1.5 

Chemical structure of P-Phenylenediamine  

 

Note. The image was created to represent chemical structure of P-Phenylenediamine. “by Chong, H., et 

al., Para-phenylenediamine containing hair dye: An overview of mutagenicity, carcinogenicity and 

toxicity. 2016. 6(5): p. 1000403.” [123]. 

1.5 Scope of This Study 

The general aims of this research is to synthesize zwitterionic cellulose with multi 

coordination site and use it for extracting toxic ions (cationic and anionic) present in 

wastewater and other contaminated water. 

 

http://en.wikipedia.org/wiki/organic_compound


23 

The sub aims include:  

1. Develop a chemical method to produce 3D cellulose with multi coordination sites  

2. Develop a chemical method to add the zwitterionic functionality to the 3D 

cellulose.  

3. Evaluate the efficiency of prepared polymer as an adsorbent for toxic cationic 

metals and nonmetal anions. 

4. Use different spectroscopic methods to describe the new adsorbent. 

 

 

 

 

  



24 

Chapter Two 

Experimental Part 

 

2.1 Materials  

Chemicals and reagents used in this work were purchased from Sigma-Aldrich chemical 

company (Jerusalem) and used as received. The chemicals include Sodium periodate 

(NaIO₄), Methanol, 2-Propanol, Hydroxylamine hydrochloride (NH₂OH.HCl), p-

Phenylenediamine, Acetic acid, Sodium borohydride (NaBH₄), 1,3-Propane sultone.  

All reagents used were of analytical grade. Deionized water was used to prepare all 

solutions. Cellulose used in this work was extracted from olive industry solid waste 

(Jeft) by a chemical process that was developed at the laboratories of An-Najah 

National University-Nablus/Palestine. 

2.2 Instruments  

The following equipment were used in this research: pH meter (JENWAY, model: 

3510), water shaking bath (Daihan Labtech, 20.0 to 250.0 rpm Digital Speed Control), 

Fourier-Transform Infrared Spectrophotometer (FT-IR) (Nicolet iS5, iD3 ATR, Thermo 

Fisher Scientific), Flame Atomic Absorption Spectrometer (ICE 3000 series AA 

System, Thermo Scientific), and Inductively Coupled Plasma Mass Spectrometer ICP-

MS (ICE 3xxx C113500021 v1.30). 

2.3 Polymer synthesis 

2.3.1 Activation of microcrystalline powder cellulose  

The first step in the process involves activation of cellulose. This activation was 

achieved by adding 10.0 g microcrystalline cellulose to 500 ml distilled water and kept 

stirring by a magnetic stirrer for 6 hour. 

 

 



25 

2.3.2 Oxidation of microcrystalline cellulose 

This step involves oxidation of cellulose to cellulose-2,3-diladehyde (Cel-Ald). 

Activated microcrystalline powder cellulose (10.0 g, 0.062 mol of anhydroglucose 

repeat unit) and an excess of NaIO₄ (16.0 g, 0.075 mol) was added to a 500.0 mL of 

distilled water in a beaker (1000 ml). The beaker wrapped completely with aluminum 

foil.  

After being stirred by a mechanical mixer in a hot water bath (40.0°C) for 24.0 hours, 

the beaker was then filtered, and any side products or remaining chemicals were 

removed by repeatedly washing the product in water and methanol.  

The product was analyzed by FT-IR after dried at room temperature.  

2.3.2.1 Degree of substitution 

To 50.0 ml of propan-2-ol, The oxidized cellulose was put in 1.0 g. 10 minutes of 

stirring the suspension were followed by the addition of 10 mL of distilled water. Using 

a 5.0% diluted solution of HCl, the pH of the mixture was decreased to about 3.5, and it 

was then stirred for an additional 30.0 minutes. 

Hydroxylamine hydrochloride was prepared as an aqueous solution (NH₂OH.HCl,‌5.0% 

by mass). Using an HCl solution that was 5.0% diluted, the pH was changed to 3.5.  

The two liquids mentioned above were combined and stirred for 12 hours. Then, 0.5 N 

NaOH was added to the solution to titrate it to pH 3.5 [111, 124].  

The aldehyde content was determined by applying the following equation:  

[   ]  
(               )

   
                                Eq. 1 

Where; 

 [Ald]: degree of substitution  (mmol/AGU). 

V NaOH : volume of NaOH (mL). 

N NaOH : normality of the NaOH (eq/L). 



26 

WOC : oxidized cellulose dry weight (g). 

2.3.3 Crosslinking of cellulose 2,3-dialdehyde 

The polymer that carries imine and amine functional groups was produced by reacting 

cellulose dialdehyde with PPD to form modified cellulose. 

2.3.3.1 Preparation of 2,3-cellulose diimine  

Oxidized cellulose powder (1.0 g, 0.0062 mol) and excess PPD (1.0 g, 0.0062 mol) 

were added to a 100.0 mL round bottom flask with a magnet stir bar, 50.0 mL of 

methanol was added as the solvent. Then to it was added a 1.0 ml of acetic acid as a 

catalyst. A condensation reaction occurs at about 70   for 24 hr. After reaction was 

completed, the imine product was filtered and repeatedly methanol washed, was then 

examined by FT-IR after drying at room temperature. 

2.3.3.2 Reduction of 2,3-cellulose diimine to 2,3-cellulose diamine   

Imine conversion to an amine was carried out using sodium borohydride (0.5 g, 0.15 

mol) that was added to a suspension of cellulose diimine (2.0 g, 0.029 mol/AGU) in 

50.0 mL of methanol in 100 ml round bottom flask fitted with a magnet stir bar. The 

reaction mixture was stirred at room temperature for 1 hr then refluxed for 24 hr. After 

that the reaction was cooled using ice water bath and during that was treated with 2.0 ml 

water dropwise, then stirred for 30 min. The generated precipitate was suction filtered, 

repeatedly rinsed with methanol, and allowed to dry at room temperature and the 

crosslinked cellulose (Cell-X) was analyzed by FT-IR. 

2.3.4 Preparation of cellulose with zwitterionic functionality 

Cellulose diamine was added to a round-bottom flask (100 ml) equipped with a magnet 

stir bar (1.0 g, 0.0037 mol).1,3-propane sultone (0.45 g, 0.0037 mol) and 50 ml THF 

was added to the flask. For 24 hours, the reaction mixture was refluxed.  

Then the target cellulose with zwitterionic functionality (Cell-X-ZWC) was filtered, 

washed with THF, dried at room temperature before being FT-IR analyzed. 



27 

2.4 Batch Adsorption Studies 

2.4.1 Calibration curves  

In a volumetric flask a 0.15985 g of lead nitrate Pb(NO3)2 (MM= 331.21 g/mol) was 

dissolved in a 100.0 ml water to produce a stock solution of Pb²⁺ with a concentration of 

1000.0 ppm was prepared. By diluting the stock solution we prepared a number of 

standard Pb²⁺ solutions with concentrations varying from 1.0 ppm to 50 ppm. 

 Using standard solutions, batch experiments were carried out to investigate the effects 

of the initial metal ion concentration, contact time, adsorbent dosage, temperature, and 

pH on the efficiency of the adsorption process. 

2.4.2 Calibration curve for lead 

By calculating the absorbency of the reference solutions, the calibration curves for 

Pb²⁺ions were constructed using flame atomic adsorption spectroscopy (FAAS). 

Figure 2.1  

The Calibration curve for Pb²⁺ 

  

Through batch studies, the removal of Pb²⁺ heavy metal ions from aqueous solutions 

was investigated [125].  

This experiment involved adding a known quantity of polymer to a lead solution with a 

known concentration in a container, which was then placed in a shaker and submerged 

in a bath of water. Then, all samples was filtered and analyzed for its residual 

y = 0.0061x - 0.0014 

R² = 0.9998 

-0.05

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.0 10.0 20.0 30.0 40.0 50.0 60.0

A
b

so
rp

ti
o

n
 (

%
) 

Concentration of Pb(II) (ppm) 

Calibration Curve 



28 

concentration. Atomic mass spectroscopy (AAS)  was used to determine the 

concentration of Pb²⁺.  

Also, the equilibrium adsorption capacity (qe) and removal percentage (E%) were 

calculated by using equations 2 and 3 shown below [116, 126-130] : 

   (
(     )

 
)                                       Eq. 2 

   (
(     )

  
)                                  Eq. 3 

Where: 

qe : the equilibrium adsorption capacity of the adsorbate (mg/g). 

m : the mass of adsorbent (g). 

V : the volume of Pb²⁺ solution (L). 

C0 (mg/L) and Ce (mg/L) : the initial and equilibrium concentration of Pb²⁺, 

respectively. 

2.4.3 The influence of adsorbate (Pb²⁺) concentration on adsorption percentage 

In order to determine the optimum Pb²⁺ ions concentration, five samples we prepared 

each containing 20.0 mg of adsorbent was mixed with 10 ml of each standard solution 

(5.0 ppm, 10.0 ppm, 15.0 ppm, 20.0 ppm, and 50.0 ppm). while maintaining the other 

conditions for the five samples constant (Temp = 25 °C, pH = 4.88, time = 30 min). To 

examine the remaining lead concentration in each solution, the filtrate of the solution 

was analyzed by FAAS.  

2.4.4 The influence of contact time on adsorption percentage 

There were six solutions prepared, each with 10.0 ml of the optimum adsorbate 

concentration, 10.0 ppm of lead, 20 mg of adsorbent, 25 , and a pH of 4.88. Thus, all 

variables were held constant with the exception of the shaking time.  

Using a thermostat shaker, the six samples were shaken for 5, 10, 15, 20, 25, and 30 

minutes. The filtrate was utilized in the FAAS measurement of the residual lead in each 

solution.  



29 

2.4.5 The influence of polymer dose on adsorption efficiency 

In order to study the effect of polymer dosage four samples of Pb²⁺ (10 ml of each) with 

the optimum concentration of 10.0 ppm and a pH of 4.88 were prepared. Then the 

polymer was added for each sample with known weights of 10 mg, 15 mg, 20 mg, and 

25 mg.‌ 

The four samples were shaken using a thermostat mixer at 25 °C for 20 minutes. The 

remaining lead concentration was determined by filtering all the samples and analyzing 

the filtrate by FAAS.  

2.4.6 The Influence of temperature on adsorption percentage  

Four samples were generated in order to examine the impact of temperature on 

adsorption, each one contains 10 ml form the 10 ppm lead standard solution and loaded 

with a 20 mg of polymer.  

Shaking was done on the samples at various temperatures 15, 20, 25, and 45    for 20 

min, and a pH of 4.88. After the procedure was finished, each solution was filtered out, 

and the remaining lead in each solution was measured using FAAS.  

2.4.7 The influence of pH on adsorption percentage  

To investigate the impact of pH, the proper parameters (contact duration, adsorbent 

dosage, temperature, and standard concentration) were used. 

The solutions pH was maintained at 3 to 13. After adding 20 mg of each polymer to 10 

ml of a 10 ppm lead standard at 20°C, the samples were purified, and FAAS measured 

how much lead was still present in each solution. 

2.5 Adsorption isotherm 

before and after adsorption, the metal ion concentration was measured. Two models, 

i.e., the Langmuir and Freundlich isotherms were used to measure the distribution of 

metal ions on the polymer's surface after equilibrium at a constant temperature [131, 

132]. 

The Langmuir model assumes that an adsorbate monolayer would form on an adsorbent 

surface that is homogeneous. 



30 

 

  
 

 

(          )
 

 

    
                                      Eq .4 

Where; 

Ce : the ion equilibrium concentration (ppm). 

Qmax : The adsorbent monolayer adsorption capacity (mg/g). 

KL : The Langmuir affinity constant (L/mg). 

The adsorption between the adsorbate molecule and the adsorbent with heterogeneous 

surface is, nonetheless, described by the Freundlich model. 

          
 

 
                                       Eq .5 

Where; 

Kf is the Freundlich constant (mg/g). 

2.6 Adsorption kinetics 

The optimal contact time, pH, It is essential to perform kinetic studies to understand the 

process by which metal ions are adsorbed and the process pathway.  

metal ion concentration, temperature, and polymer dose were used to study the 

adsorption kinetics. 

In 10.0 mL of a Pb²⁺ solution with a concentration of 10.0 ppm, a pH   7.0, and a 

temperature range of 20 to 25 °C, about 20 mg of the polymer was added. 

The adsorption process has been explained using a variety of kinetic models [133, 134]. 

One was a pseudo-first order model [135-137]: 

  (     )                                      Eq. 6 

The other was pseudo-second order [136, 137] : 

 

  
 

 

(    )
 (

 

  
)                                        Eq. 7 



31 

qe: mass of adsorbate at equilibrium / mass of adsorbent (mg/g)  

qt: the mass adsorbate/adsorbent mass at time t (mg/g). 

 K1 : the first-rate constant (min⁻¹ ). 

K2 : constant of the second-order rate (g/mg. min ). 

2.7 Adsorption Thermodynamic 

In order to investigated the adsorption performance several thermodynamic parameters 

it must be taken into consideration such as Gibbs free energy (    ) which 

demonstrated the spontaneity and feasibility, when (     ) the reaction was 

spontaneousat a certain temperature, enthalpy (   ), if (     ) the process s 

exothermic, and entropy (   ) [138, 139]. 

This parameters were calculated using the following equations [140]: 

                                   Eq. 8 

Where 

 ∆G  : the change in Gibbs free energy (J/mol).  

∆H° : the change in enthalpy (J/mol). 

 ∆S° : the change in entropy (KJ/mol.K).  

T : the absolute temperature (K). 

The relationship between the Gibbs free energy and the equilibrium constant [134, 140]: 

                  (2)                                  Eq.9 

R: the universal gas constant (8.314 J.mol⁻¹. K⁻¹). 

Kd : the thermodynamic equilibrium constant that equals (
  

  
) with a unit of (mol or 

L/g). 

Substitution of equation 9 into equation 8 [140]: 



32 

                                         Eq. 10 

Divided both side by RT [134, 140]: 

     
   

 
  

   

  
                                 Eq. 11 

So plotting lnKd against (1/T) in the Van’t Hoff plot will give a slope with a gradient of 

(-∆H°/R) and an intercept of (∆S°/R). 

It should be noted that the sign of -∆H° determines whether the gradient is positive or 

negative. As a result, K increases with temperature in an endothermic reaction while it 

decreases in an exothermic reaction. 

2.8 Wastewater Purification  

For this study, in order to evaluate the effectiveness of the polymer produced during the 

removal of harmful metals from water, a sample of wastewater was taken from one of 

the Palestinian regions sewage system. One sample was prepared, containing 10 mL of 

sewage and 20.0 mg of polymer. The polymer was mixed with sewage, and the 

optimum parameters (temperature, dosage, time, and pH) were selected. 

Metal ions in the sample, including their kinds and concentrations, which was compared 

with a control sample of sewage water, were identified using the ICP-MS technique. 

(The An-Najah National University's Water Center in Nablus, Palestine, conducted the 

analysis). 

 

 

  



33 

 Chapter Three 

Results and Discussion 

3.1 Polymer Synthesis 

3.1.1 Oxidation of cellulose to cellulose
-2,3-

diladehyde (Cell-Ald) 

Sodium periodate solution (NaIO4) was used to oxidize cellulose in accordance with a 

technique created by Jackson and Hudson [141, 142]. It is known that periodate can 

oxidize an organic compound with vicinal dihydroxyl group to dialdehyde. The reaction 

conditions and quantity of reagents required to accomplish the oxidation were optimized 

to obtain highest yield possible of cellulose dialdehyde with high aldehyde content.  

In Jackson and Hudson method Periodate (NaIO₄) in an aqueous solution is used to treat 

cellulose in a system that is completely dark. Periodate binds to the adjacent C2 and C3 

hydroxyl groups, causing the C2-C3 bond to break and the hydroxyl groups to be 

oxidized and converted to dialdehyde as shown in Scheme 3.1 [116, 143, 144]. 

Scheme 3.1 

 cellulose is transformed into cellulose-2,3-dialdehyde 

 

Note. The image was created to represent mechanism of transformed cellulose to cellulose-2,3-

dialdehyde. “by . and احمذ‌  Synthesis of Three Dimensional Cellulose Diamine Polymer for ,ب.ق.

Wastewater Purification. 2018, An-Najah National University.” [116]. 

 

 



34 

Scheme 3.2 

 oxidation of cellulose, reaction mechanism 

 

3.1.1.1 Degree of aldehyde substitution  

The hydroxylamine hydrochloride method was used to calculate the proportion of 

aldehyde substitution in the cellulose dialdehyde carried on by the periodate oxidation 

reaction [116, 124, 130]. 

 In this procedure, a predetermined quantity of dialdehyde cellulose (DAC) was reacted 

with hydroxylamine-hydrochloride to produce oximes as illustrated in the experimental 

chapter.  

A sodium hydroxide solution with a concentration 0.50 M was used to back titrate the 

HCl that was released throughout the reaction to an end point of pH 3.50 and the degree 

of aldehyde substitution was calculated by the following Eq.12 [116, 130]: 

[   ]  
(               )

   
                        Eq. 12 

According to the reaction conditions mentioned in the experimental chapter, the DAC 

prepared in this work gave a degree of substitution of 1.98 aldehyde group/ anhydro 

glucose repeat unit of anhydroglucose. 

3.1.1.2 Conformation of aldehyde presence by FT-IR 

FT-IR spectrum shown in Figure 3.1 represents the FTIR spectrum of untreated 

cellulose. The O-H  stretching shows a large peak at 3361 cm⁻¹, the band at 2920 cm⁻¹ 

represents the stretching vibration of the C-H bond , peak at 1024 cm⁻¹, associated with 

C-O-C bond [112, 145].  



35 

Figure 3.1 

FT-IR spectra of microcrystalline cellulose  

 

The IR spectrum of the oxidized cellulose Figure 3.2 exhibits a peak at approximately 

1735 cm⁻¹ corresponding to the C=O of aldehyde [146]. The absence of a strong 

aldehyde peak may be caused by hydration and the formation of hemiacetals [147, 148]. 

Since cellulose had to be dried under extreme temperature in order to remove the water, 

this could cause aldehyde functional group oxidation or degradation. 

 

 

 

 

 

 

 

  

O-H C-H 

C-O-C 



36 

Figure 3.2 

FT-IR spectra of cellulose after oxidation (Cellulose Dialdehyde) 

 

 

 

3.1.2 Preparation of Cellulose crosslinked with Diamine  

The aldehyde functional group is able to be adapted to many functions or activities 

[149], It is highly reactive and may be converted into several function groups. It can be 

undergo further oxidation to form carboxylic groups, for example [150, 151], or reduced 

to alcohols [150, 152], or converted to imine by reacting it with amine [153]. The imine 

then could be reduced to an amine. Due to its lone pair of electrons, amine can combine 

with metal ions. It was transformed to an imine and then reduced to an amine [111, 

116].  

Aldehyde's carbonyl group contains an electrophilic carbon, after losing the water 

molecule, the electrophilic carbon reacts with the amine group in a condensation 

reaction to generate an imine, as shown in Scheme 3.3 [154]. 

 The scheme shows the reaction between cellulose dialdehyde and p-Phenylenediamine. 

The nucleophilic attachment of an amine to the molecule's carbonyl group first produces 

an intermediate. Following that, a proton is transferred from nitrogen in PPD to oxygen 

O-H C-H 

C-O-C 

C=O 



37 

in the aldehyde's carbonyl group, and lastly, water is lost in an eliminating reaction to 

create the imine product. 

Scheme 3.3 

 The transformation of cellulose dialdehyde into cellulose diamine 

 

3.1.2.1 FT-IR of cellulose imine 

We notice that the aldehyde domain at about 1700 cm
-1

 has disappeared and the 

appearance of the C=N (imine) at 1632 cm
-1

 and C=C of benzene at 1513 cm
-1

, also we 

noticed that the appearance of C-N at about 1260 cm
-1

 and at 3358‌  cm
-1

 is the 

stretching of  the O-H group. (Figure 3.3).  



38 

Figure 3.3 

FT-IR spectra of Cellulose Diimine. 

 

3.1.3 Conversion of Cellulose Diimine to a cellulose Diamine by Reduction  

Sodium borohydride was used to reduce cellulose imine, the reaction usually takes place 

in methanol, and it is a direct forwarded reaction Scheme 3.4.  

PPD was chosen because it forms a crown amine with a strong affinity for metal when it 

crosslinks to the cellulose chains. 

 

 

 

 

 

 

 

 

 

 

O-H 

C=N 

C=C (Benzene) 

C-N 



39 

Scheme 3.4 

 Reduction of Cellulose Diimine to cellulose Diamine  

 

  



40 

3.1.3.1 FT-IR of cellulose diamine   

The disappearance of the imine band at 1675 cm is clear in Figure.3.4 of the obtained 

FT-IR spectra. aromatic rings containing C=C is detected by a signal at 1595 cm
-1

. The 

N-H band emerged at approximately 3376 cm
-1

, but it was discovered that when the 

imine groups were changed into amines, the signal size increased, and this region also 

shows the O-H band, which. As a result, the signal appears to be somewhat broader. 

Figure 3.4 

 FT-IR Spectra of Cellulose crosslinking with amine.  

 

3.1.4 Preparation of Cellulose with Zwitterionic functionality 

In the last step, cross-linked cellulose will be reacted with 1,3-propane sultone. The 

cyclic sulfonate undergoes ring opining addition reaction with the amine group in the 

crosslinked cellulose to form the target cellulose with zwitterionic functionality (Cell-

X-ZWC) Scheme 3.5 [64, 81, 155, 156]. 

 

  

C C 
(Aromatic ring) 

N-H 



41 

Scheme 3.5 

 Conversion of crosslinked Cell-Ald to cellulose based zwitterionic 

 



42 

3.1.4.1 FT-IR of Cellulose based zwitterionic.  

The C-H stretching peaks at 2901 and 2960 cm
-1 

are more intense than usual indicating 

the presence of long alkyl chain represented by butyl group.  The band at 1229 cm
-1 

represents the sulfonate group. 

Figure 3.5 

 IR spectra of Cell-X-ZWC 

3.2 Adsorption of Pb (II) 

One of the main goals of this study is to utilize Cell-X-ZWC for the removal of 

hazardous, heavy metals from industrial wastewater. This procedure was carried out by 

examining the adsorption efficiency of the prepared polymers (Cell-X-ZWC) to adsorb 

Pb²⁺ ions. According to section 2.4.  

The procedure was done by investigating the removal capabilities of PPD  towards Pb²⁺. 

Atomic adsorption spectroscopy was used to calculate the remained heavy metal ion 

concentrations. the percentage of removal was determined using Eq.13 [157]. 

 

 

C-H (Stretching) 

C-H (Stretching) 

SO3
- 

N-H 

C C 
(Aromatic ring) 



43 

            (   
  

  
)                             Eq.13 

Where; 

Ci : zero time concentration of metal ion in solution (ppm). 

Cf : Concertation of metal ion after the adsorption (ppm). 

Under experimental conditions, qe (mg/g)  is the adsorption capacity determined for 

various concentrations of ions at equilibrium [158]. 

   (
(     )

 
)                                                               Eq.14 

where; 

m: the mass of adsorbent (g). 

V: the volume of Pb²⁺ solution (L). 

C0 : concentration of metal ion in solution at time zero (ppm). 

Ce : Concertation of metal ion after the adsorption (ppm). 

3.2.1 Adsorption of Lead Ions (Pb2+) 

3.2.1.1 The influence of Pb2+ Initial Concentration 

This was done to evaluate how the concentration of metal ions affected the rate of Pb²⁺ 

metal ions removal from solutions. Lead solutions with a various concentration and 20.0 

mg of polymer was used.  

The other parameters (temperature, pH, shaking time, and solution volume) were set at 

25 °C, 4.88, 30 minutes, and 10.00 ml according to experimental part sec. 2.4.3. 

Table 3.1 shows the result obtained for the effect of the concentration of adsorbent on 

the adsorption of Pb²⁺ ions. 

 

 



44 

Table 3.1 

Effect of adsorbate concentrations on Pb²⁺ ions adsorption 

Initial concentration of 

Pb²⁺ (ppm) 

Final concentration of 

Pb²⁺ (ppm) 

Adsorption 

(%) 

Residual 

(%) 

Qe 

(mg/g) 

5.0 0.56 88.79 11.21 2.22 

10.0 0.91 90.90 9.10 4.55 

15.0 3.60 76.00 24.00 5.69 

20.0 6.81 65.94 34.06 6.59 

50.0 18.27 63.47 36.53 15.87 

The adsorption capacity and removal percentage as a function of initial adsorbate 

concentration are shown in Figure 3.6 (in appendix B). 

As Figure 3.6 (a) (in appendix B) shows, a proportional relationship was noticed 

between Pb²⁺ ion concentration and the %adsorption. The percent adsorption increase 

with increasing the initial concentration and reaching a maximum percentage when the 

initial concentration reached 10.0 ppm, then started to decline, and becomes steady at a 

concertation over 20 ppm the maximum percent of removal was 90.90 %.   

As lead ions concentrations increases as long as vacant sites are available, the rate of 

adsorption declines when the vacant sites become occupied‌[100].  

Most lead ions were adsorbed into the polymer mass at low lead concentrations and 

bound to the active sites, where they remained until all the active sites were occupied. 

The absorption process reaches a peak at 10 ppm. Following this concentration, the 

surface layer is covered with Pb²⁺ and this limits the adsorption process and stop the 

absorption of further lead ions‌[100]. 

Figure 3.6 (b) (in appendix B) shows the relation between the initial concentration of 

adsorbate and the adsorption performance. The high driving force of the mass transfer 

and the abundance of unoccupied receipting sites‌[40]. 

 The adsorption capacity initially rises quickly as the adsorbate concentration rises until 

it reaches a plateau, at which point it can be concluded that all of the adsorption sites 

have been occupied‌[40]. 



45 

3.2.1.2 Influence of contact time 

Removal of lead as a function of time was studied under optimum initial ions 

concentration 10.00 ppm, and other parameters such as pH, temperature, dosage volume 

of adsorbate (4.88, 25  , 20.0 mg, 10 ml ) were kept constant. The effect of adsoprtion 

time on Pb²⁺  removal was studied using contact time values that ranged from 5-30 

minutes. The influence of contact time on adsorption percentage are presented in Table 

3.2. 

Table 3.2 

 Effect of the contact time on Pb²⁺ ions adsorption 

Contact time 

(min) 

Initial 

concentration of 

Pb²⁺ (ppm) 

Final 

concentration 

of Pb²⁺ (ppm) 

Adsorption 

(%) 

Residual 

(%) 

Qe 

(mg/g) 

5 min 10.0 3.07 69.26 30.74 3.46 

10 min 10.0 1.44 85.58 14.42 4.28 

15 min 10.0 1.53 84.69 15.31 4.23 

20 min 10.0 1.34 86.59 13.42 4.33 

25 min 10.0 1.78 82.22 17.78 4.11 

30 min 10.0 1.62 83.77 16.23 4.19 

As shown in Figure 3.7 (a) (in appendix B), From 5 to 15 minutes, the removal 

percentage was gradually increased; after that, it nearly remained constant. The 

optimum contact time was chosen to be the one that typically results in the lowest 

residual concentration of adsorbate.  

The results shown in Figure 3.7 indicate that the optimum adsorption performance 

occurred at 20 minutes with 86.59 % removal for Pb²⁺, when all active sites were filled. 

As a result, minimal adsorption occurred when the contact time was short because there 

was insufficient energy to drive lead ions into the polymer's pores. Better %adsorption 

was achieved as a result of the lead ions adsorbed more quickly when the contact time 

was increased because they were easily dispersed to the pores and surface‌[159]. 

Contact time is another crucial factor to consider when evaluating how favorable the 

adsorption process is. The short time to  reach adsorption equilibrium suggests that 



46 

larger treatment volumes or batches can be treated in a low time interval, increasing 

removal effectiveness and lowering water treatment system costs‌[40].  

The presence of abundance vacant binding sites on the adsorbent surface causes the 

adsorption capacity often increases quickly during the first contact period. The rise in 

adsorption capacity gradually decreases until it levels off, indicating that the adsorption 

equilibrium has been achieved [40, 160].  

This is because as contact time increases, the number of vacant adsorptive sites 

decreases and collision  between the adsorbate and adsorption sites meet much higher 

resistance‌[40, 160]. 

Figure 3.7 (b) (in appendix B) displays a plot of adsorption capacity versus contact 

time variation. The plot indicates that the adsorption capacity is initially greatly 

enhanced and then gradually decreases over the period of 10 minutes. After 20 minutes, 

adsorption stopped and reached equilibrium‌[160].  

3.2.1.3 Influence of Adsorbent Dosage 

The influence of adsorbent dosage on Pb²⁺ removal process was essential to study since 

it relates to the amount of available active state. To determine the optimum quantity of 

adsorbent Cell-X-ZWC that gave the best and highest adsorption percentage, the 

solutions concentration, and the contact time were set at, 10 ppm, and 20 minutes, 

respectively.  

Other parameters such as temperature, volume, and pH were kept constant, 25   10 ml, 

and 4.88, respectively.  

The highest removal was obtained at the addition of 20 mg adsorbent for Pb²⁺ removing. 

The results are presented in Table 3.3. 

 

 

 

 

 

 



47 

Table 3.3 

Effect of the adsorbent dosage on Pb²⁺ ions adsorption 

Polymer 

dosage (mg) 

Initial 

concentration of 

Pb²⁺ (ppm) 

Final 

concentration of 

Pb²⁺ (ppm) 

Adsorption 

(%) 

Residual 

(%) 

Qe 

(mg/g) 

10 10.0 4.54 54.63 45.37 2.73 

15 10.0 3.66 63.36 36.64 3.17 

20 10.0 1.23 87.72 12.28 4.39 

25 10.0 1.56 84.39 15.61 4.22 

 

As shown in the above figure (Figure 3.8(a)) (in appendix B), as the adsorbent dose 

increases, the absorption percentage increases, which could be related to the availability 

of abundant vacant sites until it reaches maximum indicating the reaching of the 

adsorption equilibrium, after that the removal percentage declines as the dosage 

increases, due to the limited total available sites. The  adsorption percentage was higher 

at 20 mg with 87.72 % removal for Pb²⁺, so 20 mg was the optimum adsorbent dosage‌

[40, 161]. 

Adsorbent dosage (mg) is an important factor in estimating adsorption capacity and 

removal efficiency. 

 Figure 3.8(b) (in appendix B), illustrates a typical relationship between adsorption 

performance and adsorbent dosage.  

Due to the abundance of unoccupied binding sites, the adsorption capacity increases 

rapidly with an increase in adsorbent dosage before gradually plateauing as a result of 

the saturation of adsorption sites on the adsorbent surface.  

Similarly, Figure 3.8(b) illustrates how an excessive increase in adsorbent decreases 

adsorption capacity by increasing the number of vacant binding sites. Another reason 

for the decline in adsorption capacity could be the possibility of particle aggregation at 

high concertation of adsorbent, which results in a drop in the adsorbent's total surface 

area‌[162, 163]. 



48 

3.2.1.4 Influence of Temperature 

The optimum values for dosage, concentration, contact time, and pH were constant at 

20.0 mg, 10.00 ppm, 20.00 min, and 4.88, respectively, to study the impact of 

temperature on Pb²⁺ ions adsorption utilizing Cell-X-ZWC which ranged from (15 -

45)°C (sec.2.4.6). The results are presented in Table 3.4 and Figure 3.9(in appendix B) 

summarized the results. 

Table 3.4 

Effect of the temperature on the adsorption of  Pb²⁺ ions 

Temperature 

( ) 
Initial concntration 

of Pb²⁺ (ppm) 

final concntration 

of Pb²⁺ (ppm) 

Adsorptio

n (%) 

Residua

l (%) 

Qe 

(mg/g

) 

15 10 1.42 85.79 14.21 4.29 

20 10 1.19 88.09 11.90 4.40 

25 10 1.28 87.20 12.80 4.36 

45 10 2.47 75.32 24.68 3.77 

Temperature is another crucial factor since it can affect the activation energy of the 

adsorption system, which in significantly influence the removal rate and adsorption 

capacity.  

When the effectiveness of the adsorption is improved by raising the temperature, this 

process should be endothermic; otherwise, it should be exothermic [164].  

In the endothermic process the adsorption capacity and removal rate are increased by 

rising the temperatures because of the increasing rate of effective collision (with enough 

energy to surpass the activation energy) between the metal ion and the adsorption sites 

on the adsorbent surface [165]. 

Figure 3.9 (a) (in appendix B) shows that adsorption decreased as temperature 

increased, the maximum removal percentage can be achieved at 20  , with removal of 

88.096%, so it is the optimum temperature. However, the rate of Pb²⁺ ion removal 

decreases as the temperature rises from 25°C to 45°C, showing that neither cooling nor 

heating the solution is required to adsorb the metal ion. 



49 

From the Figure 3.9 (b) (in appendix B) it can be observed that the effect of increasing 

the temperature is to decrease the adsorption capacity. 

The results showed that the exothermic and spontaneous character of Cell-X-ZWC 

adsorption processes. The kinetic energy of the adsorbed particles rises with 

temperature, increasing the probability that they will separate from the adsorbent 

surface [166, 167]. Furthermore, the decrease in adsorption at higher temperatures may 

be the cause of the increase in ion solubility with temperature [168]. 

3.2.1.5 Influence of pH on rate of adsorption  

The pH of the metal ion solution is a crucial factor in controlling the metal removal 

process because it influenced the binding site for heavy metals. the optimized 

experimental conditions were held constant (10.00 ppm solution concentration, 20.00 

min, contact time, temperature 20  , and Cell-X-ZWC,20.00 mg.  

As mentioned in the experimental section, the effect of pH on the polymer's capacity for 

adsorption was investigated (sec. 2.4.7). Table 3.5 presents the results about the effect 

of pH value on Pb²⁺ ions adsorption. 

Table 3.5 

Effect of pH level on Pb²⁺ ions adsorption 

pH 
Initial concntration 

of Pb²⁺ (ppm) 

Final concentration 

of Pb²⁺ (ppm) 

Adsorption 

(%) 

Residua

l (%) 

Qe 

(mg/g

) 

3.53 10.0 0.56 94.40 5.61 4.72 

5.48 10.0 0.33 96.69 3.31 4.83 

7.21 10.0 0.12 98.77 1.23 4.94 

9.14 10.0 0.19 98.15 1.86 4.91 

11.38 10.0 0.49 95.11 4.89 4.76 

Figure 3.10(in appendix B) illustrates the results using a range of pH values, from 

basic mediums with a pH of 11.38 to acidic mediums with a pH of 3.53. 



50 

From Figure 3.10 (a) (in appendix B), the maximum adsorption for Pb²⁺ ions occurred 

at a pH of   7.21.  pH value increased, adsorption increased up and reached the highest 

at pH   7.21 then decreased which means prefers acidic medium over alkaline one.  

Transfer to basic medium decrease the adsorption. Likewise in the Figure 3.10 (b) (in 

appendix B) the adsorption capacity increases as the pH value increases until it reaches 

a plateau at pH   7.21 then the adsorption capacity decreased in alkaline medium pH‌

>7.21.  

The fact that metal oxide starts to form at higher pH values can be used to explain the 

decreasing behavior of the Pb²⁺ removal ratio and adsorption capacity after the 

polymer's optimal pH [169]. 

3.3 Optimum adsorption parameters 

The optimum adsorption parameters for Pb²⁺ ions are shown in Table 3.6. 

Table 3.6  

Optimum Adsorption Parameters for lead ions 

Adsorbent Metal ion 
%Adsorption 

 

Parameters 

dosage (mg), concentration 

(ppm), Contact time (min), Temp 

(°C), pH 

Cell-X-ZWC Pb²⁺ 97.43% 20mg, 10ppm, 20min, 20 ,  7.21 

 

3.4 Adsorption analysis  

3.4.1 Adsorption Isotherm 

To examine the produced polymer adsorption equilibrium effectiveness (cellulose-based 

polumer) in removing Pb²⁺ ions, at equilibrium. The Langmuir (Eq. 15) and Freundlich 

(Eq. 16) isotherms models were utilized [132, 170, 171].  

Once equilibrium was achieved under constant temperature, both adsorption isotherm 

models were used to assess the adsorbate spreading on the surface of the adsorbent 

[112].  



51 

There are several isotherm models that apply at all temperatures, including Langmuir, 

Freundlich, and others. When the ions are arranged in a monolayer on the surface of the 

adsorbent, the Langmuir model guides the adsorption process.  

The Freundlich model is used when the adsorption process between the adsorbent and 

the adsorbate is conducted on a large number of heterogeneous layers‌[171].   

These models all have applicable equations, and the data will be fitted into these 

equations. The correlation coefficients, R², are one of the factors that can influence the 

sort of isotherm model‌[112, 170]. 

3.4.1.1 Langmuir adsorption isotherm 

The fundamental principles of the Langmuir model are a finite number of active sites 

that are homogenously distributed over the adsorbent's surface, Monolayer adsorption 

and desorption on one active center have no impact on the adsorption on another active 

center because all active centers have the exact same level of energy‌[172-176].  

The adsorption follows this model if the figure plot between 1/qe vs 1/ce shows a 

straight line with a high R² value. It was presented as Eq .15: 

 

  
 

 

(          )
 

 

    
                                                       Eq .15 

Where; 

Ce : the ion equilibrium concentration (ppm).  

At equilibrium, qe is the mass of the adsorbate that is absorbed per mass of the polymer 

(mg/g). 

Qmax : The adsorbent’s monolayer adsorption capacity (mg/g). 

KL : The Langmuir affinity constant (L/mg) that is related to the adsorption energy. 

The separation factor (RL), also known as the equilibrium parameter, is a dimensionless 

constant that can be used to characterize the basic characteristics of the Langmuir 

isotherm‌[175, 177]. 



52 

   
 

       
   

 

     
                                     Eq .16 

Where 

 C0 : is the initial concentration (mg/L). 

KL : is the Langmuir constant related to the energy of adsorption (L/mg). 

 The value of RL indicates the shape of the isotherms to be either unfavourable (RL > 1), 

linear (RL = 1), favourable (0 < RL <1) or irreversible (RL = 0). 

Figure 3.11 (in appendix B) Represent Langmuir model for adsorption of Pb²⁺ on Cell-

X-ZWC. 

Table 3.7 

 Langmuir model values 

Concentration 

(ppm) Ci 

[Pb²⁺] 

(ppm) Ce 
qe 1/Ce 1/qe 

5 0.56 2.22 1.78 0.45 

10 0.91 4.55 1.09 0.22 

15 3.60 5.69 0.28 0.18 

20 6.81 6.59 0.15 0.15 

50 18.27 15.87 0.05 0.06 

 

Table 3.8  

Langmuir Adsorption isotherms parameters for Cell-X-ZWC 

Langmuir isotherms 

Metal ion Adsorbent R² Qmax KL RL 

Pb²⁺ Cell-X-ZWC 0.88 11.16 0.49 0.17 

 

As shown on Table 3.8, the separation factor (RL ) range from (0 < RL <1) which 

indicates  that the shape of the isotherms is favorable. This replicates the strong 

attraction that the polymers made of cellulose have for the investigated metal ions. 



53 

3.4.1.2 Freundlich isotherm model 

The adsorption processes on heterogeneous surfaces with a non- uniform distribution of 

energy of adsorption and multilayer adsorption are discussed and illustrated in the 

Freundlich isotherm model.  

If the graph of lnqe versus lnCe displays a straight line with an R² number close to 1, then 

adsorption follows to this model. 

The Freundlich isotherm has the following empirical formula: 

          
 

 
                                     Eq .17 

Where; 

Kf is the Freundlich constant, which is proportional with the adsorption capacity (mg/g). 

The heterogeneity coefficient (g/L) is denoted by the letter n, which indicate how 

favorable or unfavorable the adsorption process (g/L). 

Figure 3.12 (in appendix B) represent Freundlich model for adsorption of Pb²⁺ by Cell-

X-ZWC. 

Table 3.9 

 Freundlich model values 

Concentration 

(ppm) Ci 

[Pb²⁺] 

(ppm) Ce 

qe lnqe lnCe 

5 0.56 2.22 0.79 -0.58 

10 0.91 4.55 1.51 -0.09 

15 3.60 5.69 1.74 1.28 

20 6.81 6.59 1.89 1.92 

50 18.27 15.87 2.76 2.91 

 

  



54 

Table 3.10  

Freundlich Adsorption Isotherms parameters for Cell-X-ZWC 

Freundlich isotherms 

Metal ion Adsorbent R² n Kf 

Pb²⁺ Cell-X-ZWC 0.89 2.15 3.44 

 

In all cases, as show in Table 3.8  and Table 3.10, Compared to the Langmuir 

isothermal model, the Freundlich isothermal model's correlation coefficient (R²) is 

higher and much closer to 1.  

So, the adsorbent (Cell-X-ZWC) obeys this model and adsorption process is not only at 

the surface, but also at the multilayer of the polymer, and adsorption processes on 

heterogonous surfaces. 

3.4.2 Adsorption kinetics 

One of the major features that must be understood before any adsorbent can be applied 

is adsorption kinetics [162]. 

In order to examine the adsorption process involves rate of adsorption and mechanism 

of adsorption of Pb²⁺ the kinetic models pseudo-first order and pseudo-second order 

were utilized. The employed kinetic models are shown in Eqs. 18 and 19 [178-180]. 

 3.4.2.1 Pseudo-first order model 

  (     )                              Eq. 18