Environmental pollution has been a serious concern worldwide. Many degradation methods have been developed to clean sites contaminated with pollutants. More knowledge and better understanding in this field will help to protect our environment. The goal of the research in this thesis is to gain a better understanding of the mechanism of organic pollutant degradation in Fenton reactions and sonochemical reactions. Fenton degradation uses hydroxyl radical to oxidize organic compounds. The radical is produced by catalytic decomposition of hydrogen peroxide with Fe(II). Further research has found that addition of cyclodextrins can enhance degradation efficiency of hydrophobic organic pollutants. To study the mechanism of the enhancement, pollutant-cyclodextrin-Fe(II) aqueous systems were studied by fluorescence and NMR techniques. The results indicated the formation of pollutant/carboxymethyl-beta-cyclodextrin/Fe(II) ternary complexes in the solution. With the ternary complex, the catalyst Fe(II) becomes closer to the pollutant, therefore leading to more efficient hydroxyl radical attack on the pollutant. Additional studies showed that hydropropyl-beta-cyclodextrin, beta-cyclodextrin and -̀cyclodextrin bound pollutant well, but bound Fe(II) poorly. Sulfated-beta-cyclodextrin did not bind well with pollutant although it bound Fe(II) well. Sonochemical degradation is another important pollutant treatment method in practice. It was found that phenol sonolysis can be enhanced by volatile hydrogen atom scavengers such as carbon tetrachloride and perfluorohexane. The non-volatile hydrogen atom scavenger iodate did not enhance phenol degradation. The first order rate constant for aqueous phenol degradation increased by about 2.2-2.8 times in the presence of 150 uM carbon tetrachloride. In the presence of less than 1.5 uM perfluorohexane the first order rate constant increased by about 2.3 times. Hydroquinone was the major observed reaction intermediate both in the presence and absence of hydrogen atom scavengers. Hydroquinone yields were substantially higher in the presence of hydrogen atom scavengers, suggesting that hydroxyl radical pathways for phenol degradation were enhanced by the hydrogen atom scavengers. The additives investigated in this study have potential to improve pollutant degradation efficiency. Other fields may also benefit from the information gained in this study. For example the improvement could be achieved in synthetic processes that rely on hydroxyl radical as a key intermediate.

Organic pollutants which are present in industrial wastewater discharge are recalcitrant in nature and are not easily degradable by conventional aerobic microbial treatment. For the effective degradation of such pollutants advanced oxidation processes are used. . In recent years, two AOPs, viz. photocatalysis (using semiconductor oxides such as TiO2) and sonolysis, which is ultrasound irradiation of aqueous pollutant solution, have been extensively investigated. Simultaneous application of these two techniques, known as Sonophotocatalysis, has been found to give enhanced degradation than any of these techniques applied individually.

Fundamental Mechanistic Studies of the Photo-Fenton Reaction for the Degradation of Organic Pollutants.

Advanced Functional Materials and Methods for Photodegradation of Toxic Pollutants addresses the potential role of visible active photocatalytic methods for the removal of various emerging and persistent organic pollutants (POPs.) Describing the classification, sources and potential risks of emerging organics in water bodies and the environment, the book covers the different synthesis methods of visible active structured photocatalysts and structure related properties to their applications in photocatalytic processes for the removal of antibiotics, pharma and heavy metal pollutants. This book provides an invaluable reference to academics, researchers and technicians in chemical engineering, chemistry and environmental science. In addition, the mechanistic insights associated with the interaction of advanced functional materials and water pollutants along with the possible reaction pathway occurring during the visible light induced photocatalytic processes together with toxicity are discussed in detail along with the reutilization of catalysts, supporting the inherent reaction conditions performed with natural conditions. Covers the recent progress in nano photocatalytic materials Explores the mechanism of photocatalytic degradation of pollutants Includes the controlled synthesis of nanostructured photocatalysts and their modifications for targeted pollutants

Photocatalysis is a reaction which is accelerated by light while a heterogeneous reaction consists of two phases ( a solid and a liquid for example). Heterogeneous Photocatalysis is a fast developing science which to date has not been fully detailed in a monograph. This title discusses the basic principles of heterogeneous photocatalysis and describes the bulk and surface properties of semiconductors. Applications of various types of photoreactions are described and the problems related to the modeling and design of photoreactors are covered.

This volume discusses the theoretical fundamentals and potential applications of the original electro-Fenton (EF) process and its most innovative and promising versions, all of which are classified as electrochemical advanced oxidation processes. It consists of 15 chapters that review the latest advances and trends, material selection, reaction and reactor modeling and EF scale-up. It particularly focuses on the applications of EF process in the treatment of toxic and persistent organic pollutants in water and soil, showing highly efficient removal for both lab-scale and pre-pilot setups. Indeed, the EF technology is now mature enough to be brought to market, and this collection of contributions from leading experts in the field constitutes a timely milestone for scientists and engineers.

Photocatalysts in Advanced Oxidation Processes for Wastewater Treatment comprehensively covers a range of topics aiming to promote the implementation of photocatalysis at large scale through provision of facile and green methods for catalysts synthesis and elucidation of pollutants degradation mechanisms. This book is divided into two main parts namely “Synthesis of effective photocatalysts” (Part I) and “Mechanisms of the photocatalytic degradation of various pollutants” (Part II). The first part focuses on the exploration of various strategies to synthesize sustainable and effective photocatalysts. The second part of the book provides an insights into the photocatalytic degradation mechanisms and pathways under ultraviolet and visible light irradiation, as well as the challenges faced by this technology and its future prospects.