Anti-algal activity of Fe2O3-TiO2 photocatalyst on Chlorella vulgaris species under visible light irradiation.

Abstract

Many industries located in coastal areas use a large amount of seawater. Algal biofouling can be a major problem that hinders the efficiency of these industrial facilities. In most cases, seawater requires algal removal pre-treatment to avoid or mitigate biofilm formation. To remediate green microalgae, Fe2O3-TiO2 nanoparticles with 2.5% w/w Fe2O3 were applied as a visible light driven photocatalyst. The anti-algal activity of the photocatalytic pre-treatment using green microalgae, Chlorella vulgaris was tested. The experiments were carried out in freshwater, artificial seawater, and real seawater. Effect of photocatalyst dosage, visible light intensity, and water salinity on the removal of microalgae was investigated. The highest inactivation efficiency of Chlorella vulgaris was achieved under 55 W/m2 visible light irradiation when 0.25 g/L of Fe2O3-TiO2 photocatalyst was used. The photocatalytic removal kinetics of Chlorella vulgaris followed the pseudo first order Langmuir-Hinshelwood model. The results revealed that the efficiency of photocatalytic removal of algae decreased with increasing of seawater salinity. The anti-algal activity of Fe2O3-TiO2 nanoparticles was attributed to the generation of reactive oxygen species (ROS) through the photocatalytic process. H+ radical was shown to be the most important ROS that nanoparticles produced in the aqueous media. Using Fe2O3-TiO2 nanoparticles in photocatalytic pre-treatment could be an efficient environmental-friendly method for micro-algal remediation in seawater under visible light.