Cu, Ag–containing systems based on coal gangue as catalysts for highly efficient antibiotics removal via persulfate activation under visible light irradiation

Abstract

Zeolite socony mobil–5 (ZSM–5) was synthesized from solid waste coal gangue and used as a support for co–loading copper and silver in order to degrade tetracycline hydrochloride (TC) through persulfate activation under visible light irradiation. XPS analyses indicated that silver and copper species existed in the form of Ag0 and Cu2+ in ZSM–5 before catalytic reaction, and shifted to Ag0 and Cu2+/Cu+ after catalytic reaction, respectively. By experimental parameter optimization, it was found that the catalyst with 15% of Cu and 5% of Ag supported on ZSM–5 (15% Cu–5% Ag/ZSM–5) presented excellent degradation efficiency toward TC, which could degrade 75% TC within 60 min. The ESR and radical trapping experiments indicated that ∙OH and h+ played the dominant roles in TC degradation process. It was proposed that the electrons transfer between CuO and Ag as well as the redox cycle of Cu+/Cu2+ improved the generation of active free radicals and enhanced the degradation efficiency of TC.