Effect of surfactants on photocatalytic toxicity of TiO₂- based nanoparticles toward Vibrio fischeri marine bacteria

The activity of seawater microorganisms is of great concern around the world because of high biofilm formation potential. Visible-light photocatalysis is considered to be one of essential methods for microbial control which could effectively address this challenge. Herein, the effect of three different chemical surfactants, i.e., anionic, cationic, and non-ionic, on the photocatalytic toxicity of Fe₂O₃-TiO₂ nanoparticles towards Vibrio fischeri, a marine bacterium, was investigated under 55 w/m² of visible light irradiation. Although all types of surfactants alone showed slight cytotoxic effects on bacteria, reduction of photocatalytic disinfection efficiency was observed in the presence of different surfactant concentrationsdue to the competitive degradation of bacteria and surfactants competing for oxidative power. The reduction ranges of the photocatalytic toxicity of the Fe₂O₃-TiO₂ toward bacterial cells depended on the kind and concentration of the surfactants in the solution. The most significant reduction of photocatalytic toxicity was caused by the addition of non-ionic surfactants, Triton X-100. Moreover, independent of surfactant presence in reaction media, the photocatalytic inactivation rate of V. fischeri followed first order kinetics.