Efficient persulfate activation by carbon defects g-C3N4 containing electron traps for the removal of antibiotics, resistant bacteria and genes

Abstract

Contaminants such as antibiotics and the resulting antibiotic-resistant bacteria (ARB) and antibiotic-resistant genes (ARGs) have become a hot topic in the field of wastewater purification. In this study, a method was proposed to simultaneously remove antibiotics and reduce ARB and ARGs with C–(N)3 defect carbon nitride-coupled persulfates (CN-CV2/PS). The location of the C–(N)3 defects was determined by a combination of spectroscopic techniques and electron spin resonance tests. Based on photoluminescence and electrochemical tests, and deformation charge density calculations, electron traps were generated at defect sites resulting in enhanced electron–hole separation. The mineralization rates of CN-CV2/PS for six typical antibiotics were 11–17% and 21–28% higher than those of CN-CV2 and conventional CN, respectively. Over the same reaction time, the inactivation rates of CN-CV2/PS for E. coli and E. faecalis screened from wastewater treatment plants were 3.6 and 2.7 log higher than that of CN-CV2. In addition, CN-CV2/PS showed a reduction rate of more than 2.5 log for tetA and intI1. DFT calculation showed that due to the formation of defects, the adsorption energy between the PS and catalysts increased from –8.924 eV (CN) to –18.340 eV (CN-CV2). At the same time, the effective stretch of peroxide bond of PS changed from 1.505 Å to 1.519 Å. Both results indicated that the activation of PS was significantly enhanced in the presence of the modified CN-CV2. The synergetic effect of CN-CV2/PS is expected to remove the antibiotics, resistant bacteria and genes efficiently in future wastewater advanced treatment.