Persulfate activation using a novel Palladium/Tungsten (III) oxide-supported graphene nanocomposite for Escherichia coli inactivation: efficiency, mechanisms, and stability

This study aimed to investigate the effectiveness of a Palladium/Tungsten (III) oxide-supported graphene (Pd/WO3/G) nanocomposite in catalyzing PS activation for the inactivation of E. coli in water. The XRD, FTIR, and SEM-EDS techniques were utilized to analyze and determine the crystalline and electronic structure of the nanocomposite, and the inactivation mechanism was evaluated using the EPR method and specific scavengers. Results showed that the inactivation of E. coli by Pd/WO3/G, Pd/G, and WO3/G was 6.92, 6.02, and 3.8 logs, respectively, indicating a synergistic effect among the different components of the nanocomposite in PS activation. Additionally, Pd was more effective in inactivating E. coli compared to WO3 due to more persulfate activation. The finding indicated highest inactivation was achieved at pH 5. Increasing the PS concentration and catalyst dosage led to higher inactivation rates, whereas the inactivation rate decreased with an increase in bacteria density. The catalyst was found to be reusable, with only 1.72 log of E. coli inactivation occurring after four consecutive runs. The effective inactivation of E. coli was achieved through the generation of •OH and SO4•¯ made possible by PS activation. However, the results indicated that SO4•¯was the primary reactive ROS involved in E. coli inactivation.