Removal of carbamazepine in water by electro-activated carbon fiber-peroxydisulfate: Comparison, optimization, recycle, and mechanism study

Treatment of a persistent organic pollutant, carbamazepine (CBZ), in aqueous solution by a novel and sustainable method, Electro-activated carbon fiber-peroxydisulfate (E-ACF-PDS), was investigated and compared with ACF adsorption, Peroxydisulfate (PDS), ACF-peroxydisulfate (ACF-PDS), E-Pt (Pt-plating titanium as cathode in electrolysis), E-ACF (ACF as cathode in electrolysis), and Electro-Pt-peroxydisulfate (E-Pt-PDS) processes, respectively. The removal rate of CBZ by E-ACF-PDS was 98.78% in 30 min, which was much higher than that of the others. Besides, several tests were performed to investigate the role of operational conditions (pH, peroxydisulfate concentration, electrode potential, temperature, and water matrix) in E-ACF-PDS process. Moreover, it is worth noting that even after recycling ACF for 100 times, the removal rate of CBZ in 30 min decreased only slightly from 98.78% to 97.35% in E-ACF-PDS process. In addition, the surface functional groups, FTIR spectrum, Raman spectrum, BET surface area, micropore volume, and SEM images of ACF before and after long time service were investigated and the results revealed that the ACF could maintain the original features in E-ACF-PDS process even after 100 cycles, while the ACF alone was seriously damaged in ACF-PDS process after 50 cycles. These results suggested that the E-ACF-PDS process could remarkably enhance the removal of CBZ in aqueous solution due to the simultaneous adsorption of contaminants and the increase in the generation of active radicals on ACF. The electrons on cathode could inhibit the destruction of ACF caused by chemical oxidation such as sulfate radicals, hydroxyl radicals, and peroxydisulfate. Therefore, the E-ACF-PDS process may provide an effective and sustainable approach to water treatment for the elimination of contaminants of emerging concern in water.