Removal of 2,4-dichlorophenol by fluidized-bed fenton process

Abstract

2,4-dichlorophenol has been widely used in the industries of dyes, pharmaceutical , pesticides and wood preservative. It is considered as a toxic and carcinogenic chemical. Therefore, the industrial wastewater contaminated with this chemical need to be treated before release to the environment. This research aims to investigate the degradation of 2,4-dichlorophenol by fluidized-bed Fenton process. In this study, Box-Behnken experiment design was applied to assess the effects of variables and determine the optimum condition. The result reveals that the initial H2O2 concentration was the main factor affecting the degradation of 2,4-dichlorophenol whereas pH, Fe[superscript 2+]and the amount of carrier were consider as less significant factors. The optimum condition for removal of 1 mM of 2,4-dichlorophenol was at pH 3, 100 grams of SiO[subscript 2] , 0.25 mM of Fe[superscript 2+]and 10 mM of H[subscript 2]O[subscript 2] which could be predicted to obtain the removal efficiencies of 99.86%, 60.49% and 14.38 % for 2,4-dichlorophenol, COD and total ion ,respectively. With comparison between Fenton and fluidized-bed Fenton process at the optimum condition, the removal efficiency of 2,4-dichlorophenol from both processes were almost the same while the higher total iron removal was found in fluidized-bed Fenton process. Since the advantage of fluidized-bed Fenton can reduce the amount of sludge via crystallization process. Moreover, the kinetic study was also investigated. The overall kinetic equation, under the studied ranges of 0.1 to 1 mM of Fe[superscript 2+], 1 to 20 mM of H[subscript 2]O[subscript 2] , 0.5 to 5 mM of 2,4-dichlorophenol , 100 grams of SiO[subscript 2] and pH 3 can be described as follows : d[2,4-DCP]/dt = 1.84x 10[superscript -1] [Fe[superscript 2+]][superscript 0.51] [H[subscript 2] O[subscript 2] ] [superscript 0.19] [2,4-DCP] [superscript 0.68]