Capturing copper on cow dung-based biochar adsorbents for reuse in water bacterial decontamination

Abstract

Dealing with the waste contamination (e.g., livestock wastes, heavy metals, microorganisms, etc.) arising from modern agriculture and industry is a great challenge to the living surroundings and public health. Herein, we converted cow dung into biochar that functioned as green adsorbents for effective removal of the Cu2+ ions from water, coupled with their reutilization in water bacterial decontamination. The Cu2+ ions were recovered on cow dung-based biochar from wastewater and in situ reduced by NaBH4 to copper nanoparticles (Cu NPs) with a mean diameter of 51.8 nm. The as-recovered Cu NPs existed in a combined form of metallic Cu and Cu2O, which exhibited high antibacterial efficiency against Escherichia coli and Staphylococcus aureus, as well as pathogens in livestock wastewater. Antibacterial mechanism test demonstrated that the Cu NPs inactivated bacteria via a synergistic effect of reactive oxygen species-dependent oxidative stress and release of Cu2+ ions.