Fabricating 3D hierarchical hollow CoAl-LDHs@CoSx-rGO ball-flower for degrading sulfamethoxazole via visible-light coupling PMS activation: Performance and mechanism insight

Abstract

Sulfamethoxazole (SMX) is an extensively applied antibacterial drug, and it is also a pollutant that poses a serious threat to human and ecosystem health. In this research, a 3D hierarchical hollow ball-flower structure catalyst (CoAl-LDHs@CoS_x-rGO) was tailored for the first time to efficiently degrade SMX via visible light coupling PMS activation. A series of characterizations confirm that the target catalyst is successfully prepared and the optimized 0.1CoAl-LDHs@CoS_x-rGO sample possesses superior specific surface area of 306.0 m²/g, and significantly higher photocurrent response and lower electrochemical impedance. More importantly, 0.5 g/L of the sample can degrade 98.59 % of SMX within 50 min via visible light coupling PMS activation, and after 7 degradation cycles, the degradation rate only decreased by 8.49 %. A series of parameters that affect degradation rate have been optimized in detail. Capture experiments and ESR indicate that e⁻, •OH and SO₄^•− make major contributions to degradation, and visible light coupling PMS activation generates stronger signals than alone visible-light or PMS system. LC-MS, TEST toxicity assessment and theoretical calculation were conducted to elucidate degradation route and intermediate toxicity. The research provides a new approach to design catalysts with highly exposed activity sites for efficiently removing SMX from environmental water.