CROSSLINKED CELLULOSE WITH TRIDENTATE COORDINATION SITES: SYNTHESIS AND APPLICATION IN EXTACTION OF TOXIC METAL IONS FROM WASTEWATER
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Date
2023-09-07
Authors
Shahd Hani Mahmood Shaheen
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Abstract
Background: Water pollution that comes from industrialization and rapid urbanization has been considered as serious problem because water is one of the vital resources for life, and it is important to all humans, environment, society and economy. Heavy metals (Ag, Hg, Pb, Cr, Cu…) are among the contaminants that are of primary concern and need to be removed from waste water by various technologies that include adsorption as the wide used treatment process. Low cost and effective adsorbents from natural polymers are of great interest for heavy metal removal from waste water and researches have been directed toward modifying these natural adsorbents to enhance their adsorption efficiency.
Objectives: The main goal from this work is to prepare a crosslinked carboxymethyl-cellulose polymer functionalized with 2-aminopyridine in order to make it excellent binder to heavy metal for application in waste water purification.
Methodology: The method of preparing the polymer begins with a reaction between carboxymethyl cellulose (CMC) polymer and 2-aminopyridine to convert the carboxylic group into amide then crosslinking the prepared polymer by diethylene triamine (DETA) for extra stability. The resulting polymer was analyzed by Fourier Transform -Infra Red (FT-IR), Atomic Force Microscopy (AFM) and Thermal Gravimetric Analysis (TGA).
Results: The percent removal of Cu2+ ion by the prepared polymer was investigated under the following parameters: temperature, time, pH, adsorbent concentration and adsorbent dosage. The maximum removal of Cu2+ by CMC/2-aminopyridine polymer is 92.25% at pH = 7.23, temperature 19 ⁰C, time 20 min, adsorbent concentration 20 ppm and polymer dose 10 mg. The adsorption isotherm, kinetics and thermodynamics were investigated to determine the mechanism and spontaneity of the adsorption process and the results revealed that it is exothermic (ΔH° < 0), spontaneous (ΔG° < 0) and occurs spontaneously at low temperatures (ΔS° < 0). The adsorption follows Pseudo-second order model with (R2 = 0.99) and the Langmuir adsorption isotherm was applied with (R2 = 0.93)
Conclusion: The target polymer was prepared and confirmed by IR, it is thermally stable based on TG analysis and it results in high percent removal of the heavy metal.
Keywords: Carboxymethylcellulose, Water pollution, wastewater treatment, heavy metals, Copper, 2-aminopyridine, DETA