Doctor of Philosophy
Chemical and Biochemical Engineering
Ray, Ajay K.
Nowadays, the release of different new contaminants, also known as emerging contaminants, in water and wastewater bodies are increasing with each passing day. Emerging contaminants primarily include pharmaceutical and personal care products and endocrine disruptors. Advanced oxidation processes are receiving an immense importance in the last few decades due to their abilities to degrade a vast range of organic and inorganic pollutants. This thesis explores the efficiency of different advanced oxidation processes in degrading emerging pollutants as well as conventional organic pollutants. Heterogeneous photocatalysis is a well-studied advanced oxidation process, which involves the use of light energy to excite semiconducting materials to produce a pair of electron/hole, that eventually facilitates the oxidation of organic pollutants by generating hydroxyl radical and superoxide anion. The process has been found to be highly effective in degrading emerging contaminants like artificial sweeteners and caffeine, where almost complete degradation of these contaminants has been found under experimental conditions. However, the major drawbacks of heterogeneous photocatalysis is the large band gap of the semiconducting materials, making the process expensive UV-light driven, and high recombination rate of the formed electron/hole pair, reducing the efficiency of the overall process. A solar cell technology called dye-sensitization was applied to solve the enigmas of the photocatalytic process. The novel approach of using a natural dye to replace heavy metal and organic synthetic dyes increased the sustainability of the technology and uniqueness of the process. The technology was found to be highly effective in the removal of an organic pollutant namely methylene blue. Tetraoxy high valent iron(VI), known as ferrate(VI), received great attention as an oxidant, coagulant and disinfectant. However, few emerging contaminants like caffeine, artificial sweeteners, etc. are recalcitrant towards oxidation by ferrate(VI). A novel approach of activating ferrate(VI) by acid was studied here for enhanced oxidative transformation of artificial sweetener. Significantly, almost complete removal (i.e. 93.6%) of the sweetener by acid-activated Fe(VI) was achieved at Fe(VI) to ACE molar ratio of 6.0 in 1 minute. ii The findings of this research stimulate further studies on the new advanced oxidation techniques for the removal of emerging and conventional organic pollutants.
Ghosh, Malini, "Enhanced Oxidative Transformation of Conventional and Emerging Organic Contaminants by Visible and Solar Light Driven Photocatalysis and Activated Ferrate(VI)" (2019). Electronic Thesis and Dissertation Repository. 6129.