Comparison of various advanced oxidation processes for the degradation of 4-chloro-2 nitrophenol

In the present study an attempt is made efficiently to degrade USEPA listed 4-chloro-2-nitrophenol (4C-2-NP), widely available in bulk drug and pesticide wastes using various advanced oxidation processes (AOPs). A comparative assessment using various AOPs (UV, H2O2, UV/H2O2, Fenton, UV/Fenton and UV/TiO2) was attempted after initial optimization studies, viz., varying pH, peroxide concentration, iron concentration, and TiO2 loading. The degradation of the study compound was estimated using chemical oxygen demand (COD) reduction and compound reduction using spectrophotometric methods and further validated with high performance liquid chromatography (HPLC). The degradation trends followed the order: UV/Fenton > UV/TiO2 > UV/H2O2 > Fenton > H2O2 > UV. It can be inferred from the studies that UV/Fenton was the most effective in partial mineralization of 4C-2-NP. However, lower costs were obtained with H2O2. Kinetic constants were evaluated using first order equations to determine the rate constant K. (C) 2007 Elsevier B.V. All rights reserved.