This work investigated the toxicity of CuO nanoparticles (NPs) to Escherichia coli in the presence of fulvic acid (FA), an important fraction of dissolved organic matter (DOM) in natural water. CuO NPs (2, 6 and 10 mg/L) exhibited high bacterial toxicity, and the toxicity was significantly reduced by the presence of fulvic acid (FA, 5 and 40 mg/L). Bacteria membranes were greatly damaged by CuO NPs while FA mitigated this damage according to fluorescence dye tests and electron microscopy imaging. FA also reduced the efflux K+ ions from 11.25 to 9.59 mg/L. The reduced toxicity was due to enhanced electrostatic repulsion and surface coating by FA, therefore, the physical contact between CuO NPs and bacteria membrane was hindered. Our study implies lower bacteria toxicity by CuO NPs in DOM-rich natural water or wastewater, while higher toxicity is expected in underground water or natural water with low DOM concentration.

Fulvic acid mitigated CuO nanoparticle-induced bacteria toxicity

245th National Meeting (2013)

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