Comparative photocatalytic degradation using natural and artificial UV-light of 4-chlorophenol as a representative compound in refinery wastewater

The comparison of the degradation of 4-chlorophenol, using sunlight and a UV-lamp, was carried out using two different catalysts, Degussa P25 and Hombikat UV 100. All experiments were performed after first optimizing the catalyst concentrations and pH. The optimal concentrations for Degussa P25 and Hombikat UV 100 occurred at 7 and 10 g/l, respectively. The optimal initial pH was found to be 5 for both catalysts. The degradation rate of 4-chlorophenol is 6.4 times and 1.6 times higher when using sunlight compared to the artificial UV-lamp for Degussa P25 and Hombikat UV 100, respectively. The degradation rate of 4-chlorophenol is six times higher, compared to Hombikat UV 100, at the optimal conditions, when using sunlight and Degussa P25 as the catalyst. The chloride produced during the reaction was measured and found to be highest for Degussa P25 with sunlight as the energy source.