Promoted Generation of Singlet Oxygen by Hollow-Shell Cos/G-C3n4 Catalyst for Sulfonamides Degradation : Pms Oxidation and Electron Transfer

Sulfanilamide (SM), as one representative drug of sulfonamides, was commonly used for the prevention and treatment of bacterial infectious diseases and were extremely difficult to remove. Herein, an efficient catalyst (CoS/CN) for SM degradation was constructed by CoS self-assembling on ultra-thin g-C3N4 nanosheets. The prepared hollow-shell CoS/CN catalyst could completely degrade SM within 10 min with a rate constant (1.959 min−1) through activation of peroxymonosulfate (PMS). Experiments and theoretical calculations illustrated that that S2- acted as an electron donor to promote the generation of Co(II). The addition of g-C3N4 made the CoS/CN composite had higher conductivity and electron transfer ability than CoS, which promoted the decomposition of PMS to produce reactive oxygen species (ROSs). Singlet oxygen (1O2) was proved as the primary ROSs, and SO4•− radicals were generated during the degradation process to improve the low mineralization rate of 1O2-dominated degradation process, which derived from the oxidation process of PMS and electron transfer of g-C3N4. The results revealed the synergistic effect of free radicals and non-free radicals during the oxidation and reduction of PMS, and provided theoretical support for the efficient degradation of refractory organics in wastewater