Effect of nanoscale zero-valent iron confined in mesostructure on Escherichia coli

Nanoscale zero-valent iron particles (NZVIs) confined in the mesochannels of SBA-15 have superabilities in the remediation of contaminated groundwater. As a new kind of remediation nanomaterials, it is necessary to investigate the ecotoxicity of NZVIs/SBA-15 composites during their applications. In this study, we evaluated the toxicity of NZVIs/SBA-15 on Escherichia coli and proposed a possible mechanism. Compared with the bare NZVIs and SBA-15 surface-supported NZVIs at the same equivalent concentration of NZVIs (0.42 or 0.84 g/L), NZVIs/SBA-15 composites had a minimal cytotoxicity on E. coli, though they had the smallest iron nanoparticle size, the largest zeta potential, and the best stability in water. The mechanism may be attributed to the protection of the mesochannels and the electrostatic hindrance resulting from the silica host that could keep NZVIs from directly contacting with the cell. Thus, NZVIs confined in the mesostructures can be safely used in the remediation of contaminated natural water.