UVA and solar driven photocatalysis with rGO/TiO2/polysiloxane for inactivation of pathogens in recirculation aquaculture systems (RAS) streams

Abstract

In this study TiO2/polysiloxane(SiBi) thin films modified with different concentrations of graphene oxide (GO) were prepared by ink-jet printing on flexible polyethylene terephthalate (PET) substrates. Prepared coatings were characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), Raman and water contact angle measurements. During photocatalytic tests strong change of color of prepared coatings modified with GO was observed. XPS analysis of thin films after photocatalytic tests suggests that reduction of GO took place. Prepared coatings were studied for inactivation of microorganisms naturally occurring in aquaculture water under UVA and natural solar irradiation. Effect of rGO concentration in prepared coating on inactivation of target bacteria Aeromonas hydrophila and Citrobacter gillenii was evaluated under UVA irradiation. Aeromonas hydrophila was more sensitive to photocatalytic inactivation in comparison with Citrobacter gillenii. Higher photocatalytic inactivation of target microorganisms was attributed to thin films with concentration of rGO 1 and 5%. The rGO/TiO2/SiBi 5% were further tested for inactivation of Aeromonas salmocida, Serratia fonticola strain and Lactococcus lactis strain under natural solar light. Solar photocatalysis slightly enhanced inactivation of Aeromonas salmocida and Serratia fonticola strain, while opposite was observed for Lactococcus lactis strain