Rapid concurrent photocatalysis-persulfate activation for ciprofloxacin degradation by Bi2S3 quantum dots-decorated MIL-53(Fe) composites

Abstract

In recent years, concurrent photocatalysis-persulfate activation (CPPA) has emerged as a potential method for antibiotic removal. A highly active and stable catalyst is the prerequisites for the development of CPPA technology. Herein, Bi2S3 quantum dots (QDs) decorated MIL-53 (Fe) hybrids were synthesized for the first time by a simple chemical synthesis strategy and used for antibiotic degradation in the CPPA system. The energy band structure and optical properties show that BM has a narrower forbidden bandwidth, higher carrier separation, and transport efficiency compared to the original MIL-53(Fe). It also promotes the O2 transfer and makes the BM rich in oxygen vacancy (Ov), which becomes a bridge to connect photocatalysis and SR-AOPs. The BM-5/PS/vis system degraded over 97.4 % of the ciprofloxacin in 15 min and remained effective in the presence of common interfering substances or over a wide pH range. The quenching and trapping experiments indicate the dominance of superoxide radicals and singlet oxygen in the degradation process. The simultaneous activity of free radical and non-free routes could be responsible for the improved antibiotic degradation efficiency. This work provides a facile strategy in surface modification to improve the physicochemical properties of MIL-53(Fe) and demonstrates the catalytic role of BM in the CPPA system.