Application of Fenton Processes for Degradation of Aniline

Abstract

Fenton process is one of advanced oxidation processes (AOPs) which are considered as alternative methods for treatment of non-biodegradable and toxic organic compounds. Fenton process has been widely used in the treatment of persistent organic compounds in water. In general, the mechanism of Fenton reaction included the formation of hydroxyl free radicals, which has E◦ of 2.8 V, that can oxidize and mineralize almost all the organic carbons to CO2 and H2O (Glaze et al., 1987), by the interaction of hydrogen peroxide with ferrous ions (Walling C., 1975). The Fenton’s reagent is generally occurred in acidic medium between pH 2 -4 (Rodriguez et al., 2003). The advantage of Fenton process is the complete destruction of contaminants to harmless compounds, for instance, carbon dioxide and water (Neyen E. et al., 2003). However, its application has been limited due to the generation of the excess amount of ferric hydroxide sludge that requires additional separation process and disposal (Chang P.H., 2004). Therefore, electro-Fenton (EF) process is developed for minimizing the disadvantages of conventional Fenton process. In the electro-Fenton method, the Fenton’s regent was utilized to produce hydroxyl radical in the electrolytic cell, and ferrous ion was regenerated via the reduction of ferric ion on the cathode (Zhang et al., 2007). The regenerated ferrous ion will react with hydrogen peroxide and produce more hydroxyl radicals that can destroy the target compounds. However, the electro-Fenton reaction still faces several obstacles that must be overcome first such as the formation of ferric hydroxide sludge. Therefore, the new method which can promote the ferrous ion regeneration was focused in this part of experiment. The efficiency of pollutant removal and the reduction of ferric hydroxide sludge can be improved by using UVradiation. The photoelectro-Fenton process involves the additional irradiation of the solution with UVA light. Due to the generation of additional hydroxyl radical from the regeneration of ferrous ion and the reaction of hydrogen peroxide that reacted with UV light, so-called photoelectro-Fenton process (Brillas et al., 2000). Under UV-vis irradiation, the overall