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 "Prof. Hikmat Hilal"

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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.