Degradation of 4‐Chlorophenol by Anodic Oxidation, Electro‐Fenton, Photoelectro‐Fenton, and Peroxi‐Coagulation Processes

Abstract

The degradation of 4-chiorophenol in acidic solution of pH -3.5 has been studied by different electrochemical methods involving 11202 electrogeneration from an 02-diffusion cathode. While the solution is slowly mineralized by anodic oxidation in the presence of 11202, the rate for organic carbon removal increases notably by electro-Fenton, photoelectro-Fenton, and peroxi-coagulation, where Fe2 acts as catalyst to produce oxidizing 0H from electrogenerated H202. A complete mineralization was only reached in the photoelectro-Fenton process. For peroxi-coagulation, the removal of organic carbon in solution is mainly due to the coagulation of dechlorinated intermediates with the Fe(OH)3 precipitate formed. The decay for substrate concentration is faster by electro-Fenton and photoelectro-Fenton than by peroxi-coagulation. In all methods, the initial hydroxylated intermediate is 4-chloro-1,2-dihydroxybenzene, which is further oxidized with loss of chloride ion to yield maleic and fumaric acids. Fe3 complexes are produced in the processes using iron ions. These complexes are slowly mineralized by electro-Fenton and rapidly photodecomposed to CO2 by photoelectro-Fenton processes. The apparent current efficiencies for the mineralization processes have been determined. A general pathway for the degradation of 4-chlorophenol by the different methods studied is proposed.

Electrochemical treatment of actual sugar industry wastewater using aluminum electrode

“…These treatment processes require high capital and operating cost. Among various technologies, electrochemical (EC) treatment is one of the best economical alternative processes (Chen 2004;Ponselvan et al 2009) when conventional treatment methods fail to reduce pollution among industrial effluents (Brillas et al 1998). EC process is a recently developed technique which is being employed in the treatment of various wastewaters (Kim et al 2002;Aoudj et al 2010;Serge et al 2010;Kamaraj et al 2013;Maleki et al 2014;Ndjomgoue-Yossa et al 2014).…”

Advanced Oxidation Processes (AOPs) for Removal of Pesticides from Aqueous Media

“…Thus, although the traditional Pt anodes has been used for this purpose (Kaba et al, 1990;Kotz et al, 1991;Stucki et al, 1991;Comninellis andPulgarin, 1991, 1993;Murphy et al, 1992;Comninellis and Nerini, 1995), it are less efficient that the oxide-base electrodes such as PbO 2 (Kaba et al, 1990;Feng et al, 1995;Wu and Zhou, 2001), doped PbO 2 (Feng et al, 1995), doped SnO 2 Stucki et al, 1991;Comninellis andPulgarin, 1991, 1993;Johnson et al, 1999), IrO 2 (Comninellis and Nerini, 1995;Rodgers and Bunce, 2001) or more recently to the boron-doped diamond thin-layer anode, BDD (Gandini et al, 2000;Rodrigo et al, 2001). On the other hand, the indirect electrochemical methods involves the previous formation of oxidizing agents such as H 2 O 2 (Hsiao and Nobe, 1993;Do 1993Do , 1994Ponce de Leon and Pletcher, 1995;Brilla et al, 1996;Brillas et al, 1998;Alvarez-Gallegos and Pletcher, 1999;Harrington and Pletcher, 1999;Brillas et al, 2000;Oturan et al, 2000, Oturan, 2000Oturan et al, 2001):…”

“…The electro-Fenton and photoelectro-Fenton methods can be considered as advanced electrochemical oxidation processes, AEOPs (Brilla et al, 1996;Brillas et al, 1998;Brillas et al, 2000;Boye, et al, 2002).…”

Degradation of 2-hydroxybenzoic acid by advanced oxidation processes

“…Oxidation using aqueous hydrogen peroxide (H 2 O 2 ) in the presence of native or supplementary ferrous ion (Fe 2+ ) produces the Fenton reagent (Brillas et al, 1998), which yields free hydroxyl radicals (…”