Enhanced degradation of sulfamethoxazole by a novel Fenton-like system with significantly reduced consumption of H2O2 activated by g-C3N4/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-C3N4/MgO activated H2O2, and can reduce the H2O2 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 (1O2) through a nonradical pathway in the g-C3N4/MgOH2O2 system. The reduced H2O2 consumption was the net result of continuously-recycled H2O2 from the reactions between H2O2 and g-C3N4/MgO. Based on experimental results and theoretical calculations, the synthesis of g-C3N4 and MgO forms a N-Mg bond with strong ability to absorb electrons and the electron transfer of H2O2 to N-Mg bonding is accelerated, activation of H2O2 to generate 1O2. 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 H2O2 requirement for cost-effective remediation and treatment of organic pollutants and toxic wastes.