Environmental photochemistry Theory and application

From the Editor’s Desk
While in the applied environmental photochemistry, there are mainly three areas and each of them has many literatures in the past 20 years. The first is solar energy and chemical energy conversion, for examples dye-sensitized cell, water splitting for hydrogen generation, CO2/N2 conversion and selective synthesis. The second is environmental remediation mainly related with Advanced Oxidation Processes (Alps) like drinking water treat, wastewater treat, air purification, deodorization, sterilization and organic compounds decomposition. And the third is photo-functional materials, for examples superhydrophilicity, self-cleaning, sanitary coating and UV-blocking materials. In the first and the third areas, scientists have focused their research interests on semiconductor and modified photocatalysts of TiO2, ZnO, Fe2O3 etc. However, in the environmental remediation area, many other photochemical oxidation and reduction systems rather than TiO2 have been investigated. They are namely known as UV/O3, UV/H2O2, photo-Fenton(Fe2+-H2O2), photo-Fenton-like system (Fe2+/Fe3+-polycarboxylate complex system) and so on. Almost all the important photochemical AOPs have been applied in pilot-scale wastewater treatment in Plataforma Solar de Almeria (PSA), Spain. The aim of these application is to use solar energy
by different types of reactors into wastewater treatment.
It is very necessary to emphasize that theoretical environmental photochemistry and applied environmental photochemistry are the two sides of environmental photochemistry, which are interrelated with one another. For example, on one hand, we focus on the environmental behaviors (mainly transfer and transformation) of pollutants in aquatic system which is namely aquatic photochemical process. And, those photochemical processes are usually induced by the abundant components
in the natural waters like iron, humic substance, alga and so on. That’s so-called theoretical environmental photochemistry. On the other hand, we focus our applied environmental photochemistry research on the photochemical methods for pollution control by using AOPs mainly based on the photochemistry of iron species. The systems include traditional photo-Fenton and photo-Fenton-like systems. Theory of environmental photochemistry help us in finding new and more efficient systems for applied environmental photochemistry to destroy the emergent contaminants. In reverse, simulative research of the photooxidation or photoreduction for the purpose of pollutant removal helps to reveal the chemical mechanisms of the photochemical processes of such pollutants in the natural environments.
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