Oxygen vacancy simultaneously inducing peroxymonosulfate activation and photocatalytic reaction for highly efficient ciprofloxacin degradation

Abstract

In this paper, ZnAl-LDH with rich oxygen vacancies (E-CZA-LDH) was prepared by two steps of Co doping and alkali etching. Both methods are conducive to the formation of oxygen vacancies (OVs) to form the unique defect structure (Co-OVs or Co-OVs-VZn) with high electron delocalization in E-CZA-LDH. The OVs structures can organically couple the photocatalytic reaction and peroxymonosulfate (PMS) oxidation due to its efficient electron capture performance and high PMS adsorption capacity. As a result, E-CZA-LDH exhibits highly efficient degradation activity for ciprofloxacin (CIP) under the synergism of photocatalysis and PMS oxidation, which is 4.98 and 2.81 times higher than that in the photocatalytic and PMS systems, respectively. The oxidation process is the combined action of radical and non-radical species, the active species like SO4·-, O2·-, ·OH, h+, and 1O2 are jointly involved in CIP degradation. Liquid chromatography-mass spectrometry (LC-MS) gives the primary oxidation intermediates of CIP degradation, and toxicity assessment shows that the oxidation process decreases the environmental risks of CIP. The E-CZA-LDH demonstrates outstanding stability and reusability, making it suitable for practical application. This study might provide an excellent reference for designing and constructing low-cost and high-efficiency catalysts for pollutant degradation in the actual environment.