Z-Scheme membrane CdZnS/TiO2 heterojunction photocatalyst for efficient photocatalytic removal of Microcystis aeruginosa under simulated sunlight: Adjustable suspended depth and flexible assembly

Abstract

The application of photocatalytic technology in algae killing is limited by the non-floatability and difficulty in recycling of the photocatalysts. Loading photocatalyst on magnetic or floatable carriers is the most popular method for overcoming the above inadequacies. In this work, a CdZnS/TiO₂ membrane photocatalyst with adjustable suspended depth (include floating) and flexible assembly is designed, which is less prone to dislodgement due to in situ synthesis and has a wider range of applicability than previously reported photocatalysts. The photocatalytic removal of Microcystis aeruginosa revealed that the suspended depth and distribution format of the CdZnS/TiO₂ membrane photocatalysts have striking effects on the photocatalytic removal performance of Microcystis aeruginosa, the photocatalytic removal efficiency of CdZnS/TiO₂-2 membrane photocatalysts for Microcystis aeruginosa could reach to 98.6 % in 60 min when the photocatalysts assembled in the form of 3 × 3 arrays suspended at a depth of 2 cm from the liquid surface. A tiny amount of TiO₂ loading allows the formation of Z-Scheme heterojunction, resulting in accelerating the separation efficiency of photogenerated carriers, preserving the photogenerated electrons and holes with stronger reduction and oxidation ability and inhabiting the photo-corrosion of CdZnS.