Bismuth titanate modified and immobilized TiO2 photocatalysts for water purification: broad pollutant scope, ease of re-use and mechanistic studies

Abstract

Deposition of titanium dioxide (TiO₂) coatings onto glass beads from a P25 enriched sol of titanium butoxide is described. This method gives a robust and stable covering, to which small bismuth containing clusters of 1–5 nm have been introduced using a simple and scalable sequential ionic layer adsorption reaction (SILAR) method. This bismuth-modified TiO₂ coating has been proven to show significant improvements over the pristine TiO₂ samples for a variety of different pollutants including intermediates in consumer product manufacture, pesticides, drugs and explosives. Using scavenger tests, the mechanism of degradation for each of the pollutant molecules tested has been probed, and a thorough discussion of the differences presented. The applicability of the system has also been assessed, with ease of re-use of the photocatalyst-bead apparatus investigated through recycling tests.