Effect of toluene, an immiscible pollutant, on the photocatalytic degradation of azo dye

An adverse effect of a water-immiscible pollutant, toluene, on the photocatalytic degradation of Direct Red 80 (DR80) with TiO₂ in an aqueous solution was observed when toluene was added as a continuous free layer. However, a more efficient photocatalytic system was obtained when toluene was added in the Pickering emulsion (PE) form with TiO₂. With only UV and two different types of TiO₂ (more hydrophilic and large-sized type A TiO₂ and less hydrophilic and small-sized type B TiO₂), 44% and 59% color removal was observed, respectively. Almost 20% decrease in color removal with toluene in the continuous free layer form was observed, however, the higher color removal was obtained when toluene was added as PE stabilized with type B TiO₂ than with type A TiO₂. The higher color removal was owing to the good stability of PE stabilized with type B TiO₂.