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

摘要

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 Fe~(2+)/S_2O_2~(2-) 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 Fe~(2+) and S_2O_8(2-) exhibited a noticeable influence on CBZ removal efficiency, where [S_2O_8~(2-)] exerted more significant effects than that of [Fe~(2+)]. The optimal molar ratio of CBZ, Fe~(2+), and S_2O_8~(2-) 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 NO_3~-, SO_4~(2-) and H_2PO_4~- 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.