Enhancement the BuP Photo-catalytic degradability by UVC/ZnO through adding exogenous oxidant: mechanism, kinetic, energy consumption

Abstract This study develops UVC/ZnO (UZ) in the presence of H2O2 (UZH), as an efficient method of advanced oxidation processes, and employs it for degradation and mineralization of wastewaters containing Butylparaben (BuP). Photocatalytic experiments were carried out in a batch reactor to evaluate BuP degradation and the rate of TOC reduction. Results showed the higher efficiency of UZ than the ZnO and UV alone. The complete degradation of BuP was observed when H2O2 added in solution. The values of kobs and robs (obtained from the kinetic studies) for UZH were about 6,105 and 302 times than that of the UZ, UV alone and only ZnO alone, respectively. It is observed that, the value of electric energy per mass removed for UZH (0.004 (kWh/m3) is much less than the other processes; therefore, it can be an attractive process for environmental applications. Based on obtained results, the optimum range of parameters, considering complete degradation of BuP and mineralization rate of 36 % were estimated: pH, 9.0; initial BuP concentration, 14 mg L-1; reaction time, 90 min; ZnO, 1 g L-1 and H2O2, 100 mg L-1. Also it is found UZH process has no enough energy to complete mineralization of BUP and a post-treatment process is needed in follow.