The Fifth Palestinian International Chemistry Conference
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Browsing The Fifth Palestinian International Chemistry Conference by Author "Ahed Zyoud"
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- ItemElectrochromic Properties of Sol-gel NiO Films Dopped with Ti(2011-06-01) Atheer Abu Yaqoup; Iyad Saadeddin; Ahed Zyoud; Hikmat S. Hilal
Electrochromic films of NiO & NixTi1-xO(2-x) (with Ti concentrations 5, 10, 15, 20, 25 & 30%) have been prepared by the sol-gel route using dip coating technique onto fluorine-doped tin oxide-coated glass substrates (FTO/glass). Ethanolic sols from nickel acetate tetrahydrate (Ni(CH3COO)2 • 4H2O) and titanium isopropoxide precursors were used in the preparations. The nano-sized films were sintered in air between 250 and 300°C. Characteristics of different films were studied in a comparative manner. Photoluminescence spectra, electrochromic behavior, cyclic voltammetry, XRD, thickness and SEM have been investigated. Typically, as the TiO2 content was increased, film characteristics were enhanced. Mechanisms of coloration and morphology transformation of the layer during cycling in 0.05 M KOH electrolyte were discussed in terms of an activation and degradation period. Calculation of cathodic charge (QC ), anodic charge (Qa), Optical density & Coloration efficiency were made. Our results indicate that electrochromic and other characteristics of the NiO can be enhanced by addition of TiO2 at certain concentrations.
- ItemA New Technique to Prepare Nano-Sized CdS Films for Light-to-Electricity Conversion(2011-06-01) Sahar Khudruj; Ahed Zyoud; Iyad Saadeddin; Hikmat S. Hilal
In this study, we intend to introduce a new technique to prepare nano-sized films of CdS for the purpose of light-to-electricity conversion processes. In order to evaluate the new systems, their photo electrochemical (PEC) characteristics have been compared with conventional counterparts, in addition, their optical and structural characteristics such as SEM and XRD have been studied and compared with conventional counterparts. The nano-sized films were prepared by different techniques, namely: electrochemical (EC), chemical bath (CB) and electrochemical followed by chemical bath (EC/CB) deposition techniques. The latter technique describes the new preparation technique for CdS nano particles. All films were deposited onto fluorine-doped tin oxide-coated glass substrates (FTO/Glass). The different types of films were compared with each other by monitoring different parameters, such as: open-circuit voltage (Voc), current density (Jsc), photo (J-V) plots, efficiency and stability. Poly crystalline CdS thin films, prepared by different techniques, were modified by annealing and slow cooling to enhance PEC characteristics. The effect of treatment on film characteristics has been studied by: photo (J-V) plots, efficiency, and stability. Annealing and slow cooling showed higher conversion efficiency for each preparation technique compared with un-treated films. SEM and XRD results for prepared CdS films were consistent with the efficiency results for each preparation technique before and after modification. Annealing and slow cooling increased the grain size of CdS nano particle and consequently, increased the efficiency. CdS thin films prepared by EC/CB technique, before annealing, showed higher efficiency than films prepared by EC, but lower than CB systems. After annealing, the EC/CB prepared systems showed higher efficiency than either EC or CB prepared counterparts. The results show that the new preparation technique gives new thin films with higher efficiency and stability than earlier conventional prepared.
- ItemSensitization of semiconducting powder catalysts in water purification: Photodegradation of medical drugs and microorganisms(2011-06-01) Fedaa Salih; Ahed Zyoud; Majdi Dweikat; Hikmat S. Hilal
Photocatalytic degredation of organic contaminants in water and air attracts great deal ofattention. TiO2 is the most widely used semiconductor photocatalyst due to its high photostability,low cost, non-toxic nature, high oxidizing potential and its water insolubility underdifferent conditions. In this work TiO2 was prepared from TiCl3 then sensitized byanthocyanin natural dye extracted from Hibiscus (Karkade). The TiO2/anthocyanin systemwas then used as a catalyst to photo-degraded phenazopyridine and E-colli bacteria in water.Catalytic experiments were conducted in a 100 mL magnetically stirred thermostatedbeaker. The out-side walls of the beaker were covered withaluminum foil. Direct visible irradiation using a solar simulator halogenspot lamp (1300 Lux, 0.0001898W/cm2) was applied vertically to the photo-catalytic mixturesurface. The contaminant concentration was measured every 25 minute by polarography.TiO2 was characterized by measuring the XRD, SEM, photoluminescence, UV-visible spectra.Different parameters were studied, such as pH, contaminant concentration, catalystconcentration and temperature. The efficiency of the catalyst increased with increasing thecontaminant concentration, catalyst concentration and pH value. Photodegradtion reactionrate was temperature independent. Results and discussions will be presented together withpossible mechanisms.
- ItemSensitizing Zinc Oxide Photocatalyst with Natural dye for Water Disinfection under Sun Light(2011-06-01) Sondos Ateeq; Ahed Zyoud; Majdi Dweikat; Hikmat S. Hilal
Several procedures are commonly used for water disinfection from bacteria. Examplesare chlorination, peroxide addition, ozonation and UV irradiation. Photodegradation ofmicroorganisms has also been examined. TiO2 and ZnO were examined by researchers forinactivation of Escherichia coli and some other types of bacteria using photo-degradationtechniques.ZnO is a wide band gap (3.2 ev) semiconductor, with limited photo-catalytic applications toshorter wavelengths only, and demands UV region for excitation. However, it has attractedattention as an interesting alternative to TiO2 in dye sensitized solar cells. ZnO has theadvantage of being sensitive to solar UV light.Because only about 4% of the solar spectrum falls in the UV region, ZnO semiconductoris sensitized by dye molecules. Sensitized ZnO catalysts have been investigated for organicpollutant degradation in a safe and simple manner.In this work, ZnO semiconductor nano-particles, combined with safe low cost sensitizer(natural dye anthocyanin) was used to disinfect water from bacteria by photodegrading itwith solar simulator light. The natural dye sensitized ZnO to the visible light, as the dye hassmaller band gap and absorbs in the visible region.Illumination has been constructed by a solar simulator lamp. A pre-contaminated watersample with E-Coli bacteria was treated with the catalyst (ZnO/anthocyanin) under halogenspot lamp. A noticeable decline in bacteria concentration was observed. Contaminatedsamples were treated with naked ZnO, anthocyanin dye, and light source (without anyadditions) separately in control experiments.Up to 90% degradation was achieved by the ZnO/anthocyanin catalyst system undersolar light in 90 minutes. Effect of different parameters on reaction rate and efficiency, suchas temperature, pH, concentration and others were also studied and will be presented.