TiO2-WO3 nanocube-polyaniline hierarchical membrane for efficient removal of chromium in a photocatalytic membrane reactor

In this article, the rational design of a physically coated TiO₂-WO₃ nanocube-polyaniline photocatalytic membrane (hierarchical) reactor for the efficient reduction of chromium (VI) under visible light is discussed. The incorporation of TiO₂-WO₃ in the polyaniline (PANI) membrane provides excellent hydrophilicity and high photo-corrosion resistance and facilitates the rapid permeation of water with a flux rate of 12 L/m² h and higher Cr (VI) reduction. The exposure of bare PANI membranes in Cr (VI) solution leads to over-oxidation of PANI membrane and eventually leads to the destruction of the membrane. The hierarchical photocatalytic coating improves the lifetime of the membrane by blocking it from deprotonation. The photocatalytic membrane could offer 79.30% Cr (VI) reduction under visible light irradiation in a photocatalytic membrane reactor. After several reduction cycles, the membrane showed good self-cleaning ability. The present work suggests that TiO₂-WO₃ nanocube-coated PANI hierarchical membrane is a promising approach for the reduction and removal of Cr (VI) from wastewater.