Enhanced degradation of sulfamethoxazole by a novel Fenton-like system with significantly reduced consumption of HO activated by g-CN/MgO composite.

Advanced oxidation processes (AOP) based on nonradicals have attracted growing attentions because nonradical systems require much less oxidants and have low susceptibility to radical scavengers. Herein, a novel Fenton-like system that utilizes nonradicals was explored. It was derived from g-CN/MgO activated HO, and can reduce the HO stoichiometry from 0.94%-0.18% to 0.03%. Sulfamethoxazole (SMX), a widely used sulfonamide, was used as the model pollutant to evaluate the efficacy of the system. It was observed for the first time that organic pollutants can be degraded with singlet oxygen (O) through a nonradical pathway in the g-CN/MgOHO system. The reduced HO consumption was the net result of continuously-recycled HO from the reactions between HO and g-CN/MgO. Based on experimental results and theoretical calculations, the synthesis of g-CN and MgO forms a N-Mg bond with strong ability to absorb electrons and the electron transfer of HO to N-Mg bonding is accelerated, activation of HO to generate O. Experimental data showed that organic pollutants can be degraded rapidly over a wide pH range. Findings of this study point to a cyclical but stable Fenton-like system with reduced HO requirement for cost-effective remediation and treatment of organic pollutants and toxic wastes.