Visible-light-driven inactivation of Escherichia coli K-12 using an Ag/AgCl–activated carbon composite photocatalyst

•Escherichia coli K-12 inactivated using Ag/AgCl–activated carbon photocatalyst.•Up to 97% of bacteria inactivated in 60 min under visible light irradiation.•Mechanism of photocatalytic inactivation due to action of radicals on cell wall.

In this work, the inactivation of Escherichia coli K-12 was investigated using a novel Ag/AgCl–activated carbon composite photocatalyst under visible light irradiation. The photocatalyst was found to inactivate 97% of bacteria under irradiation for 60 min in a 5 g/L slurry. The composite also possessed some biocidal action due to the incorporated silver, however, the action of the photo-induced radical species on the bacteria seemed to dominate the inactivation process. The mechanism of photocatalysis-induced cell death was thought to be attributable to attack of radical species causing damage to the cell wall, and was probed by indirect observations of changes to cell membrane permeability and structure.