Ph.D. Program in Chemistry

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https://hdl.handle.net/20.500.11888/3208

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Browsing Ph.D. Program in Chemistry by Author "Dr. Nidal Zatar"

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    Dye-Modified Nano-Crystalline TiO2 Surfaces in Light-Driven Water Purification from Organic Contaminants
    (2005) Lamees Zuhair Abdul Razeq Majjad; Prof. Hikmat Hilal; Dr. Nidal Zatar
    Phenol and benzoic acid are examples of water contaminants that are difficult to degrade by conventional chemical and/or biological methods in water. Photo-electrochemical methods have been examined to degrade phenol and benzoic acid, in this work. Naked, and/or modified TiO2 (anatase) surfaces have been examined for such purposes. There are many researches in this field, but for the first time TiO2, modified with metalloporphyrins (MnP) and triphenylpyrilium hydrogen sulfate (TPPHS) have been prepared and used, and also for the first time the modified TiO2 systems were supported onto activated carbon (AC) and used in degradation experiments. UV light was needed for degradation of phenol and benzoic acid, giving CO2 and H2O as final products. Visible light was successfully used to degrade Tamaron insecticide using TiO2/TPPHS and AC/TiO2/TPPHS catalytic systems, which are prepared for the first time in this research.Supported and unsupported TiO2/MnP was also catalytically active in visible light degradation of Tamaron, which are also prepared for the first time in this research. All photo-degradation processes demanded oxygen but not in high concentrations. It was noticed that the degradation was also temperature, speed of stirring, catalyst concentration, and initial concentration of contaminants independent. Recovered AC/TiO2/TPPHS catalyst samples showed lower activity than fresh ones. The activity loss is attributed not to TPPHS degradation but to TiO2/TPPHS burial inside AC bulk. The results indicate the importance of TPPHS or MnP dyes in activating TiO2 in degradation processes, by behaving either as sensitizers, when using visible light, or as charge transfer catalysts, when using ultra violet light. Considering that, we propose charge transfer catalyst model for the first time.
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    Nanoparticle CdS-Sensitized TiO2 Catalyst for Photo-Degradation of Water Organic Contaminants: Feasibility Assessment and Natural-Dye Alternatives
    (2009) Ahed Husni Abdel-Razaq Zyoud; Prof. Dr. Hikmat Hilal; Dr. Nidal Zatar
    The photocatalytic degradation of organic contaminants (like dyes, insecticide, pesticide, … etc) in water, using TiO2 under UV are commonly used procedures. Modifying TiO2 with CdS also a common technique used for water purification under visible light. In this work both commercially and prepared TiO2 were used for photo-degradation of both contaminates models ( Methyl Orange MO and Phenazpyridine PhPy), TiCl3 was used as a starting rote for preparation of rutile structure TiO2 by hydrolysis. In order to sensitization of TiO2 to photoexcited under visible light, A chemical path deposition method (CBD) was used to precipitate a nonsocial particles of CdS on TiO2 particles surface. Sand was used as a supporting surface for the prepared catalyst. UV-visible scanning, photoluminescence measurements, XRD characterization, and SEM imaging were run for the prepared catalyst systems. The particles size of prepared CdS particle was found to be 20 nm. The influence of the catalyst concentration, initial contaminant concentration and pH on photo-degradation rate were studied. Turnover number and Quantum yield were also calculated for comparison study. There is no observable increases in photo-degradation rate with increasing contaminants and catalyst concentration, but a decrease in the rate was observed, no effect to the temperature on the rate, also a higher photo-degradation rate for (MO & PhPy) was observed at higher pH degrees. Voltametric analysis shows almost complete CdS decomposition during the photo-degradation process. Due to hazardous and toxicity of decomposed Cd2+ in the treated water, an alternative of natural nontoxic dyes (Anthocyanin) was used for the first time as a sensitizer for the rutile TiO2. AC was also used as a supporting substrate. Electronic absorption spectra, FT-IR spectra, and TGA analysis were applied on the prepared TiO2/Anthocyanine catalyst systems.A screen study was done to test the efficiency of the prepared sensitized catalyst, the catalyst was applied to photodegradate MO and PhPY. An observable efficiency was noted specially when using AC/TiO2/Anthocyanin at low pH in photo-degradation of MO.