Nanotech 2010

Studies on the kinetic properties of photocatalytic degradation of phenol in water using ZnO nanopowder as a photocatalyst

Y. Tao, Z.L. Cheng, K.E. Ting, X.J. Yin
Singapore Polytechnic, SG

Keywords: nanomaterials, water treatment, UV radiation, photocatalyst

Abstract:

In recent years, advanced oxidation processes (AOPs) have been proved to be one of the most effective methods to remove organic pollutants from water and wastewater. These processes are based on the generation of the strongly oxidizing hydroxyl radicals (HO), which oxidize a wide range of organic pollutants that could be present in water and wastewater. Nanpowder TiO2 and ZnO as photocatalysts in the degradation of several organic pollutants have been specially investigated due to their high photosensitivity, chemical stability and non-toxicity. In this study, the kinetic properties of photocatalytic degradation of phenol in water using ZnO nanopowder as a photocatalyst was studied based on the Langmuir-Hinshelwood (L-H) model. It was found that photodegradation rate was followed the a first order chemical reaction. This also had been proved by the statistical analysis as the correlation coefficients (R2) of the photodegradation rate of phenol were achieved higher than 0.9 for all the experiments. Furthermore, the photocatalytic activity of TiO2 was compared with that of ZnO in the removal of phenol from water. It was found that ZnO was more effective in the removal of phenol from water as compared with TiO2. The experiments on the optimization of related parameters to in the removal of phenol from water, such as the dosage of photocatalyst, the initial concentration of phenol and pH effects on the photodegradation rate, were carried out to study the removal efficiencies of phenol from water using ZnO nanopowder as a photocatalyst coupled with UVC radiation. Based on the experimental results, the lower initial concentration of phenol in wastewater such as 5 mg L-1 was more effective as compared with higher initial concentrations of phenol such as 10 mg L-1, 20 mg L-1, 30 mg L-1 and 40 mg L-1. Investigating the effects of pH and dosage of photocatalysts, the highest degradation efficiency was obtained at pH 7 and 0.5 g L-1 was the optimum dosage of photocatalyst.
 
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