Investigation on visible-light photocatalytic performance and mechanism of zinc peroxide for tetracycline degradation and Escherichia coli inactivation

In this study, zinc peroxide (ZnO2) with broad energy gap was firstly used for visible-light-induced photocatalytic degradation of tetracycline (TC) and inactivation of Escherichia coli (E. coli). A small amount of ZnO2 (10 mg) could efficiently degrade 100 mL of 50 mg/L TC in a wide pH range (4-12), and the degradation performance was rarely suppressed by common matrix species and natural water sources. Also, 100 mg/L ZnO2 could inactivate around 7-log E. coli cells within 60 min under visible-light irradiation. Quenching experiments and electron paramagnetic resonance (EPR) results confirmed that superoxide radical (.O2-) and singlet oxygen (1O2) were the main reactive oxygen species (ROS), which were attributed to the self-sensitization of TC and the photoexcitation of released H2O2 under the catalysis of Zn (OH)2 from the hydrolysis of partial ZnO2, respectively. The pathways of TC degradation and processes of visible-light-induced TC degradation and E. coli inactivation were proposed and deduced in detail. This work presented the enhanced visible-light photocatalytic activities of ZnO2 for antibiotic degradation and bacterial inactivation, and provided a deep insight into the mechanisms of visible-lightinduced TC degradation and E. coli inactivation over ZnO2.

Automated summary

In this study, zinc peroxide (ZnO2) was used for visible-light-induced photocatalytic degradation of tetracycline (TC) and inactivation of Escherichia coli (E. coli). The results showed that ZnO2 had high photocatalytic activity and could be applied in a wide range of pH values and matrix conditions. The mechanisms of TC degradation and E. coli inactivation were also investigated in detail.