Synergistic activation of persulfate by Cu(ii) and Fe(iii) enhanced with catechin for chloramphenicol removal from soil

Abstract

The combined pollution of heavy metals and antibiotics has become a serious environmental problem in recent years. In this study, an efficient and innovative technique to remove chloramphenicol (CAP), a pharmaceutical compound, from the Cu-contaminated soil was investigated. Fe(III) was added to form a bimetallic system to activate persulfate (PS) to produce reactive oxidative species (ROS). Moreover, polyphenol catechin (CAT) was used to enhance the Fe(II)/Fe(III) and Cu(I)/Cu(II) cycles, thus producing more ROS. The optimal ratio between Fe(III)/Cu(II) and the CAT concentration was determined. The bimetallic system with Fe(III)/Cu(II)/PS/CAT was more stable and efficient than monometallic ones and its efficiency in CAP degradation (100% after 2 h) was slightly affected by carbonate ions. In addition, 9 intermediate degradation products were identified, and the mineralization degree, determined by TOC analysis, reached 28.2% after 12 h. Among ROS, SO₄˙⁻, ˙OH, and Cu(III) contributed to CAP degradation by 82.5%, 12.4%, and 5.1%, respectively. Cu(I) was found to play an important role in the PS activation mechanism, especially in Fe(III) reduction. The toxicity of the treated soil significantly decreased. This study highlighted the application potential of the combination of copper and iron in the activation of PS to treat pharmaceutical pollution.