Photocatalytic degradation of water-soluble organic pollutants on TIO₂ modified with gold nanoparticles

Well characterised novel catalysts consisting of TiO₂ modified with very small amounts of gold nanoparticles have been applied to the photocatalytic degradation of two important pollutants, methyl tert-butyl ether (MTBE) and 4-chlorophenol, in dilute aqueous solution using a fixed bed flow-through photocatalytic reactor. Although the thermal processing that was necessary for coating the reactor walls with the photocatalysts did lead to some loss of performance, the net gains in activity relative to unmodified TiO₂ were nevertheless substantial and in excess of anything previously reported. Improvements in reaction rate by 50% and 100% for the removal of 4-chlorophenol and MTBE, respectively, were achieved. It was also found that effective removal of both pollutants could be achieved at water flow rates that are relevant to field applications involving the photocatalytic clean-up of contaminated groundwater. Due to their very small Au content, the cost of these materials is compatible with large scale use.