Selective adsorption and photocatalytic degradation of antibiotics by LaFeO3 modified Ag3PO4 @sepiolite composite

Abstract

This paper used a simple hydrothermal method to modify silver phosphate grown on top of fibrous sepiolite with lanthanum ferrite. The Z-scheme heterojunction constructed on the basis of sepiolite effectively improved a variety of deficiencies of the monolithic material. The performance of the catalysts was examined in terms of adsorption of sulfamethoxazole (SMX) and photocatalytic degradation of various antibiotics, mainly ciprofloxacin (CIP). For the adsorption of CIP (30 min), the composite LAE11 (51%) was much more efficient than LaFeO3 (26%), Ag3PO4 (9%) and AE (23%). After 1 h of lighting, the composite LAE11 removed up to 92% of CIP with kinetic constants 7.05, 1.92 and 2.02 times higher than those of LaFeO3, Ag3PO4 and AE, respectively. And after six cycles, the degradation efficiency of CIP still remained at 79%, which obviously improved the defect of Ag3PO4 instability. The composite LAE showed highly efficient adsorption and degradation of a wide range of antibiotics, with LAE11 showing strong selective adsorption of sulfamethoxazole (SMX), up to 93% within 30 min, and 58% for tetracycline hydrochloride (TC). The adsorption process of antibiotics fitted to the pseudo-second-order kinetic model. Under one hour of visible light irradiation, the composite LAE11 achieved degradation efficiencies of 92%, 89% and 94% for CIP, TC and SMX respectively. The experiments show that the construction of LaFeO3/Ag3PO4 Z-scheme heterojunction photocatalysts based on sepiolite not only facilitates improved adsorption performance but also provides more reaction sites and effectively enhances photocatalytic activity. The composite LAE11 has shown excellent synergy in the adsorption and photocatalytic degradation of pollutants.