Complete destruction of p-nitrophenol in aqueous medium by electro-Fenton method

An indirect electrochemical method, which is very efficient for the degrada tion of organic pollutants in water, is described. The method, named electr o-fenton, is based on electrocatalytical generation of Fenton's reagent to produce hydroxyl radicals, which are very active toward organic compounds. An industrial pollutant p-nitrophenol (PNP), was chosen for this study and was eventually mineralized. The major intermediary degradation products suc h as hydroquinone, benzoquinone, 4-nitro-catechol, 1,2,4-trihydroxybenzene and 3,4,5-trihydroxy-nitrobenzene were unequivocally identified by HPLC and GC-MS methods. The rate constants of the hydroxylation reactions were dete rmined. The mineralization of the initial pollutant and the intermediates f ormed during electro-Fenton treatment was followed by total organic carbon (TOC) analyses. Dependence of mineralization on the amount of electrical en ergy consumed is shown by the relative decrease of TOC values. A mineraliza tion reaction mechanism is proposed.