Bifunctional activation of peroxymonosulfate over CuS/g-C3N4 composite for efficient degradation of tetracycline antibiotics

Graphitic carbon nitride (g-C3N4) modified by CuS was fabricated for efficient bifunctional activation of peroxymonosulfate (PMS) and degradation of tetracycline (TC) in water. On the one hand, PMS could be activated by metal ions, and reducing sulfur species as electron donors, promoting the Cu(Ⅰ)/Cu(Ⅱ) cycle. On the other hand, under visible light excitation, CuS and g-C3N4 recombination significantly improved the separation efficiency of electron hole pairs, and electrons effectively migrated to PMS, generating more ROSs. The removal efficiency of TC reached 97.46 % in the optimal configuration. In addition, the 35 % CuS/g-C3N4/PMS/Light system exhibited excellent degradation ability of TC in different water matrix. The combination of free radicals (O2•−, •OH and SO4•−) and non-free radical (1O2) pathways enhanced the degradation of TC, in accordance with scavenging experiments and electron paramagnetic resonance (EPR) analysis. Density functional theory (DFT) calculations supported the higher adsorption energy of PMS on CuS/g-C3N4 composite in comparison to pure materials. Overall, this work demonstrates the practical relevance of CuS/g-C3N4/PMS/Light system for the efficient degradation of TC in the application of environmental remediation, offering an innovative approach for diminishing refractory organics and wastewater treatment expenses.