Coupled homogeneous/heterogeneous Fenton-like system to enhance the synchronized decontamination of aqueous tetracycline and Salmonella typhi

Abstract

Aqueous chemical and biological co-contaminants containing heavy metals, antibiotics and antibiotic resistant bacteria (ARB) are harmful for the ecological environment. An innovative degradation-inactivation mechanism and a coupled homogeneous and heterogeneous Fenton-like system were proposed herein to synchronously decontaminate aqueous tetracycline (TC) and TC-resistant Salmonella typhi (TRST). Results showed that the homogeneous Cu(II)/PMS system, wherein, trace Cu(II) and TC co-existed to form cupric complexes that activated PMS, effectively caused TC degradation and TRST inactivation by Cu(III) oxidation. However, the inactivation efficiency was only ∼ 47 % in mono Cu(II)/PMS system because of the generation of limited radicals from the conversion of Cu(III). After the addition of Fe/N/S-doped biochar (Fe/N/S-BC) to Cu(Ⅱ)-TC-TRST ternary contaminants, the heterogeneous Fe/N/S-BC/PMS system superposed on the effect of homogeneous Cu(II)/PMS system by generating abundant reactive oxygen species (ROS) and promoting TC degradation and TRST inactivation. Despite the competition of Cu(II) and TC, the coupled homogeneous/heterogeneous Fenton-like system enhanced the inactivation of TRST increasing to ≥98 %. Both radical (•OH, •O2–etc) and nonradical (Cu(III) and 1O2) pathways participated in the synchronized decontamination of TC and TRST and its antibiotic resistant genes (ARGs) in Cu(II)-TC-TRST ternary contaminants.