Peroxymonosulfate-assisted photocatalytic degradation of sulfadiazine using self-assembled multi-layered CoAl-LDH/g-C3N4 heterostructures: Performance, mechanism and eco-toxicity evaluation

Abstract

CoAl-LDH/g-C3N4 (CoAl-LDH/CN) heterostructures was prepared through self-assembly method using exfoliated CoAl-LDH and g-C3N4 nanosheets via electrostatic attraction force. The morphology and physicochemical properties characterization verified the success synthesis of layer-by-layer structure of CoAl-LDH/CN. Heterogeneous catalytic degradation of sulfadiazine (SDZ) was assessed using CoAl-LDH/CN combined with peroxymonosulfate (PMS) and visible light irradiation. A remarkable synergistic effect was obtained in SDZ removal. After 15 min, 10 μM SDZ could be removed by 87.1 % at conditions of 0.1 g/L CoAl-LDH/CN, 0.5 mM PMS, and pH = 6.0. The reusability tests signified the excellent reusing potential of CoAl-LDH/CN. Mechanism study suggested that CoAl-LDH in the heterostructures activated PMS to produce SO4– and OH, while g-C3N4 acted as dual roles: electron acceptor and PMS activator. Additionally, density functional theory (DFT) calculations successfully disclosed that the sites with high Fukin index (f0) on SDZ molecule were more vulnerable to radicals attack. Eco-toxicity evaluation signified the generation of less toxic intermediates compared to SDZ after photocatalysis. Our findings demonstrate the integration of CoAl-LDH/CN, visible light and PMS can be applied as a promising approach for efficient degradation of organic compound polluted water.