Degradation of carbamazepine by Fe(II)-activated persulfate process

•Oxidative degradation of carbamazepine by Fe(II)/persulfate process is reported. CBZ degradation rate depends on pH value and the ratio of [Fe2+]:[S2O82−]:[CBZ]. The anions NO3−, SO42− and H2PO4− caused a negative effect on CBZ degradation.•The higher the Cl− concentration, the faster the CBZ decay rate.•The presence of Cl− influences the evolution profiles of various intermediates. Experimental studies were conducted to investigate the oxidative degradation of carbamazepine (CBZ), one of the most frequently detected pharmaceuticals in various waters, by Fe(II)-activated persulfate process. Results show that the Fe2+/S2O82− process is very effective for the elimination of CBZ and characterized by a two-stage kinetics (a rapid initial decay followed by a retardation stage). CBZ degradation reaction was observed to be pH dependent and the optimum pH is 3.0 in the range of 2.00–7.87. The concentration of Fe2+ and S2O82− exhibited a noticeable influence on CBZ removal efficiency, where [S2O82−] exerted more significant effects than that of [Fe2+]. The optimal molar ratio of CBZ, Fe2+, and S2O82− is found to be 1:5:40. The effect of various inorganic anions on CBZ removal was also evaluated under the optimal conditions. The anions NO3−, SO42− and H2PO4-caused a negative effect on the performance of this process, while Cl− interestingly accelerated CBZ degradation. The higher the Cl− concentration, the faster the CBZ decay rate. The intermediates were identified during CBZ degradation with and without the presence of Cl−. The evolution of intermediates for these two scenarios was compared. The decay pathways of CBZ were proposed accordingly.