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Open Access Research article

Photocatalytic degradation of 4-chlorophenol by UV/H2O2/NiO process in aqueous solution

Roya Alimoradzadeh1, Ali Assadi1*, Simin Nasseri2 and Mohammad Reza Mehrasbi1

Author Affiliations

1 Department of Environmental Health Engineering, Zanjan University of Medical Sciences, Zanjan, Iran

2 Department of Environmental Health Engineering, School of Public Health and Center for Water Quality Research, Institute for Environmental Research, Tehran University of Medical Sciences, Tehran, Iran

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Iranian Journal of Environmental Health Science & Engineering 2012, 9:12  doi:10.1186/1735-2746-9-12

Published: 27 November 2012

Abstract

The removal of 4-chlorophenol from aqueous phase continues to be an important environmental issue. In this work, the photochemical oxidation of 4-chlorophenol in aqueous solutions in a batch reactor using ultraviolet irradiation, hydrogen peroxide and nickel oxide was studied. The efficiency of the system was evaluated with respect to reaction time, pH, feed concentration of reactants, catalyst load, light intensity, and the reaction rate constant. The concentrations of 4-chlorophenol and chloride ions were determined by high performance liquid chromatography and ion chromatography, respectively. Pure nanosized nickel oxide was characterized by X-ray diffraction and scanning electron microscopy. The results showed that the optimum conditions (the complete 4-chlorophenol removal (100%) at 60 min) were obtained at a neutral pH, with 0.2 mol/L H2O2, and 0.05 g/L of nickel oxide. However, no pH effects were observed in the range of 4–10. Analytical profiles on 4-chlorophenol transformation were consistent with the best line fit of the first-order kinetics. Moreover, the degradation rate constant increased with both UV light intensity and decreasing initial concentration of 4-chlorophenol. Finally, the results of mineralization and chloride ions studies indicated that dechlorination was better accomplished but more time was required to completely mineralize 4-chlorophenol into water and carbon dioxide.

Keywords:
4-Chlorophenol; UV light; Nickel oxide; Hydroxyl radicals; Degradation rate