Recent developments in photochemical and chemical AOPs in water treatment: a mini-review

Abstract

Photochemical and chemical oxidation methods, belonging to a wide group of advanced oxidation processes (AOPs), are extensively studied but still under constant development. The aim of this study was to review the recent developments mainly in UV/H 2 O 2 process and Fenton's reactions. Ultraviolet (UV) radiation is an essential factor in photochemical oxidation. In the development of UV radiation sources the energy efficiency and the use of toxicant free materials have become major objectives. Also the emitted wavelength plays a significant role. Besides, there are alternatives for UV radiation sources, such as radio frequency (RF) plasmas, which can operate in water without additional chemicals. A remarkable development in the field of chemical oxidation has been novel catalyst materials for Fenton's reaction enabling the efficient reaction in neutral or almost neutral conditions, instead of pH below 3. In addition, varieties of method integrations, e.g., combinations of AOPs or AOPs integrated to biological processes, and other enhancements such as combining ultrasound (US) with AOP have led to improved water treatment efficiencies.

Photophysical Behavior of Modified Xanthenic Dyes Embedded into Silsesquioxane Hybrid Films: Application in Photooxidation of Organic Molecules

“…Similar behaviors have been reported for other organic fluorophores confined into rigid matrices [30]. 4 International Journal of Photoenergy The previous observations can be rationalized considering that fluorophores dispersed in the microheterogeneous materials are able to sense environments with different polarities, viscosities, H-bonding capabilities, and so forth. In most cases, confinement affects the rates of the nonradiative relaxation processes (i.e., intersystem crossing and internal conversion) of the excited state by affecting (hindering or enabling) different vibrational modes coupled to the deactivation pathways [30].…”

“…Chemical reactions catalyzed by UV-Vis radiation of organic and inorganic sensitizers are one of the most economically viable methods for decomposing contaminants into innocuous and/or biodegradable subcomponents [3][4][5]. In particular, nano/microparticulate systems able to form stable aqueous suspensions are highly desirable due to its convenient application and efficient decontamination action in large volumes of fluids (associated with their large specific surface area) [6,7].…”

Textile Waste Water and the advanced Oxidative Treatment Process, an Overview

“…The advanced oxidative process is certainly not a very new treatment method as it has been studied extensively, but of course there is yet room for development of the process and the need to attain higher efficiencies, [50]. AOPs are generally considered as the set of chemical processes for the treatment of water and waste water by the reactions with hydroxyl radical (OH . )…”

Using central composite experimental design to optimize the degradation of real dye wastewater by Fenton and photo-Fenton reactions

“…The effectiveness of these processes has a special interest and constant development [16]. Moreover, it makes possible the achievement of high reactions yields with a low cost treatment.…”