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

Ten years after coming into force of the Stockholm Convention on Persistent Organic Pollutants (POPs), a wide range of organic chemicals (industrial formulations, plant protection products, pharmaceuticals and personal care products, etc.) still poses the highest priority environmental hazard. The broadening of knowledge of organic pollutants (OPs) environmental fate and effects, as well as the decontamination techniques, is accompanied by an increase in significance of certain pollution sources (e.g. sewage sludge and dredged sediments application, textile industry), associated with a potential generation of new dangers for humans and natural ecosystems. The present book addresses these aspects, especially in the light of Organic Pollutants risk assessment as well as the practical application of novel analytical methods and techniques for removing OPs from the environment. Providing analytical and environmental update, this contribution can be particularly valuable for engineers and environmental scientists.

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.

An introduction to the diverse industrial applications of preparative photochemistry. The authors treat topics of concern to both user and engineer: energy flux and sources, actinometry and the measurement of luminous power, photochemical reactors and the present and potential industrial applications of photochemical reactions. Domains that are simultaneously important in industrial application as well as rich in instruction are described: photohalogenation, sulfochlorination, photochemical oximation of hydrocarbons, photooxidation, and photopinacolization. Information on industrial processes, production capacities and safety concerns are examined in depth.

Population growth and industrial development have increased the amount of wastewater generated by urban areas, and one of the major problems facing industrialized nations is the contamination of the environment by hazardous chemicals. Therefore, to meet the standards, suitable treatment alternatives should be established. Advanced Oxidation Processes (AOPs) in Water and Wastewater Treatment is a pivotal reference source that provides vital research on the current, green, and advanced technologies for wastewater treatment. While highlighting topics such as groundwater treatment, environmental legislation, and oxidation processes, this publication explores the contamination of environments by hazardous chemicals as well as the methods of decontamination and the reduction of negative effects on the environment. This book is a vital reference source for environmental engineers, waste authorities, solid waste management companies, landfill operators, legislators, environmentalists, and academicians seeking current research on achieving sustainable management for wastewater treatment.

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.