Electronic Thesis and Dissertation Repository

Degree

Doctor of Philosophy

Program

Chemical and Biochemical Engineering

Supervisor

Dr. Ajay K. Ray and Dr. S. Barghi

Abstract

Comprising about 70% of the Earth’s surface, water is undoubtedly the most precious natural resource. According to the W.H.O, around 3.5 million people are dying every year from different water related diseases. Different kinds of dyes and pharmaceutical products have been detected in drinking water, all over the world. These organic compounds being non removable by traditional water purification processes, made advanced oxidation processes come into existence. Among all kind of advanced oxidation processes, photocatalytic oxidation is the most promising one. The photocatalytic process is based on aqueous phase hydroxyl radical chemistry and couples low energy UV light with semiconductors acting as photocatalyst. The slurry form of TiO2 though being efficient has several disadvantages (particularly, post treatment expensive separation steps) which brings the immobilization of the catalysts on surfaces into existence.

In this study, a TiO2-polymeric film photocatalyst was synthesized by reaction of gelatin, polyvinyl alcohol and polyvinyl pyrrolidone. TiO2 Degussa P25 powder was embedded into the polymeric matrix. The characterization of the film by OM, SEM, FTIR, revealed the topography of the catalyst films. Optimization of photocatalysts functionality was carried out by varying the cross linking methods and conducting several photodegradation reactions both under UV and solar light. Aspirin and methyl orange were chosen as model compounds, as traces of these compounds were detected in the drinking water of South-Western Ontario. The freeze-dried film photocatalyst was observed to degrade organic compounds efficiently, under both UV and solar illuminations. Degradation of high concentrated organic pollutants, was observed to follow Langmuir-Hinshelwood kinetics while at low concentration, first-order kinetics was observed. The effects of initial concentration, flow rate, pH, light intensity, photocatalyst loading, and thickness of the film on the degradation rates were studied.

Mechanism of degradation of aspirin was studied from LC/MS analysis. The TOC analysis was carried out to analyse the organic carbon content of the intermediates formed during the course of degradation. Finally, photocatalytic degradation reaction was carried out in a continuous flow reactor under LED lights. film photocatalyst holds the potential of being an efficient and economical form of future photocatalyst for water purification.

In brief this TiO2-polymeric


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