Visible-Light-Driven Photocatalytic Inactivation of Bacteria, Bacteriophages, and Their Mixtures Using ZnO-Coated HDPE Beads as Floating Photocatalyst

Abstract

Semiconductor materials used as photocatalysts are considered among the most effective ways to treat biologically polluted water. Certainly, efficiency depends on the selection of photocatalyst and its substrate, as well as the possibility of its application in a broader spectrum of light. In this study, a reactive magnetron sputtering technique was applied for the immobilisation of ZnO photocatalyst on the surface of HDPE beads, which were selected as the buoyant substrates for enhanced photocatalytic performance and easier recovery from the treated water. Moreover, the study compared the effect on the inactivation of the microorganism between ZnO-coated HDPE beads without Ni and with Ni underlayer. Crystal structure, surface morphology, and chemical bonds of as-deposited ZnO films were investigated by X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy, respectively. Visible-light-induced photocatalytic treatment was performed on the Gram-negative and Gram-positive bacteria and bacteriophages PRD1, T4, and their mixture. Higher bacteria inactivation efficiency was obtained using the ZnO photocatalyst with Ni underlayer for the treatment of S. Typhimurium and M. Luteus mixtures. As for infectivity of bacteriophages, T4 alone and in the mixture with PRD1 were more affected by the produced photocatalyst, compared with PRD1.

Research Progress on Inactivation of Bacteriophages by Visible-Light Photocatalytic Composite Materials: A Mini Review

“…The floating photocatalyst can achieve the maximum oxidation and the best light radiation, greatly improving the generation of free radicals and photocatalytic efficiency [ 52 ]. Urbonavicius et al [ 53 ] prepared ZnO-based floating photocatalysts with high-density polyethylene (HDPE) spheres with and without a Ni underlayer as the floatable substrate, respectively, and the ZnO film was deposited onto the HDPE sphere (denoted as ZnO-HDPE). It was found that the use of the ZnO-HDPE photocatalyst could inactivate the phage mixture under visible-light irradiation.…”

“… Infectivity of separate PRD1 and T4 phages and their mixture under visible-light irradiation for 1 h using ZnO-HDPE ( a ) without Ni underlayer and ( b ) with Ni underlayer. Reproduced from [ 53 ], Materials, with permission from MDPI Press 2022. …”