Advanced photocatalytic sterilization for recalcitrant Enterococcus sp. contaminated water by newly developed Z-scheme Bi2WO6 based composites under solar light

Pathogenic contamination is one of the major causes of clean water shortage, which poses great risk to human health. Herein, g-C3N4 (CN) was firstly introduced to Ag/Ag2O/BiPO4/Bi2WO6 (Ag/P/BWO) to construct a novel Z-scheme composite CN-Ag/P/BWO for disinfecting Enterococcus sp. contaminated water. CN-Ag/P/BWO showed excellent disinfection performance toward recalcitrant Enterococcus sp. under simulated solar light irradiation, achieving complete inactivation of 1.5 x 10(7) cfu mL(-1) of bacterial cells only within 60 min, which was mainly attributed to the improved light absorption ability, charge carries separation/transfer efficiency and surface wettability. Additionally, the disinfection mechanism of CN-Ag/P/BWO toward Enterococcus sp. was systematically investigated. Photogenerated active species h(+), center dot OH and center dot O-2(-) worked together and played crucial roles in photocatalytic inactivation. The antioxidant system enabled Enterococcus sp. self-protection ability at the beginning of disinfection through secreting more antioxidant enzymes. However, with accumulation of active species, bacterial cell membrane and energy system were damaged, which further led to leakage of intracellular components and decomposition of bacteria. Besides, CN-Ag/P/BWO exhibited high practicability for different environmental factors and also performed well for real lake water disinfection. The high stability further confirmed its practicability for water disinfection. This work not only systematically revealed the disinfection mechanism toward Enterococcus sp., but also provided an efficient method for water disinfection.

Automated summary

Pathogenic contamination is a major cause of clean water shortage and poses a risk to human health. This study introduced g-C3N4 (CN) into Ag/Ag2O/BiPO4/Bi2WO6 (Ag/P/BWO) to construct a novel composite CN-Ag/P/BWO for disinfecting Enterococcus sp. contaminated water. The composite showed excellent disinfection performance under simulated solar light irradiation, attributed to improved light absorption ability, charge carries separation/transfer efficiency, and surface wettability. The disinfection mechanism involved photogenerated active species working together and damaging bacterial cells. The composite also exhibited high practicability and stability for different environmental factors and real lake water disinfection, providing an efficient method for water disinfection.