New catalyst systems for the degradation of chlorophenols

Abstract

The aim of this study is to investigate new catalyst systems for the oxidative degradation of chlorophenol (CP) derivatives that have been classified as first-degree toxic pollutants. Oxidative degradation and degradation products of chlorinated phenols, namely 4-chlorophenol, 2,4-dichlorophenol and 2,4,6-trichlorophenol, are discussed in detail. Homogenous catalyst systems Fenton [Fe(II)/H(2)O(2)) and Fenton-like [Cu(II)/H(2)O(2) and V (IV)/H(2)O(2)] methods were employed at higher CP concentrations (1 x 10(-2) mol/L). Heterogeneous catalyst systems titanium dioxide [TiO(2)/UV) and silver loaded titanium dioxide [Ag-TiO(2)/UV] processes were also investigated at lower concentrations. Chemical oxygen demand (COD), which is defined as oxygen equivalent of organic matter before and after degradation system was determined. The removal of each CP was determined by GC/MS analysis after derivatization. CPs are generally resistant to degradation and in some cases oxidation byproducts are produced rather than the destruction of molecular structure. High degradation and removal efficiencies for each CP derivative have already been obtained by the Fenton system and this was supported by both GC/MS and COD results. However the Ag-TiO(2)/UV photocatalytic system achieved the most effective degradation of all CPs studied in this work. In addition, the results indicate that the silver loaded catalyst system achieves the best degradation efficiencies in a short exposure period. (C) 2011 Elsevier B.V. All rights reserved.