Effect of dissolved organic matter on the inactivation of bacteriophage MS2 by graphitic carbon nitride - based photocatalysis

Abstract

Waterborne pathogenic bacteria and viruses are of great concern to environmental and public health. This study focused on the impact of dissolved organic matter (DOM) on photocatalytic inactivation of bacteriophage MS2 by utilizing a visible-light-responded photocatalyst composed of rGO-supported g-C3N4 (7.5%GCN). The results showed that the inactivation rate of MS2 by 7.5%GCN photocatalysis was 3.20 log at λ > 400 nm and 3.27 log at λ > 305 nm within 120 min. The presence of humic acid (HA) in the water matrix led to a decline in the inactivation rate of 2.19 log at λ > 400 nm and 2.08 log at λ > 305 nm, representing a reduction of 31.56% and 36.4%. During an 8 h inactivation process in ultrapure water using 7.5%GCN photocatalysis under λ > 400 nm, steady-state concentrations of 1O2, •OH, •O2- and H2O2 were measured to be 5.67 × 10-13, 8.56 × 10-7, 1.21 × 10-5 and 7.08 × 10-5 mol/L, respectively; When in presence of HA, the concentrations of ROSs were inhibited except for 1O2. The order of ROS steady-state concentration was found to be H2O2 > •O2-> •OH> 1O2 during 7.5%GCN photocatalysis, both within and without HA. Transmission electron microscopy (TEM) analysis revealed that the distortion in the morphology of MS2, potentially leading to the disclosure of RNA. Furthermore, protein analysis indicated that the protein structure was damaged, resulting in a decrease of approximately 90% in its concentration. This study may shed light on the impact of DOM during solar light-driven photocatalysis, offering a green, environment-friendly, and sustainable water treatment process.