Effect of sulfur on the solar light photoactivity of TiO2-based photocatalysts

Abstract

Crude TiO2 derived from sulfate technology was used as a precursor for the novel solar light active photocatalysts with various sulfur content (S-TiO2). The effect of sulfur on the physicochemical properties of S-TiO2 and efficiency of ketoprofen photodecomposition under simulated solar light was investigated. Additionally, the activity of selected photocatalysts was evaluated under visible light and UV radiation. Moreover, different scavengers were applied to explore the mechanism of ketoprofen decomposition. Furthermore, the acute toxicity tests were performed to assess a toxicological effect of the decomposition products. It was proved that the sulfur content in a range of ∼ 0.7–1.2 wt% was a key factor affecting the photoactivity under simulated solar light. The most beneficial sulfur content was ∼ 0.9 wt%. It was revealed that the solar light induced photoactivity of the examined photocatalysts derived mainly from the visible light photocatalysis mechanism, with some contribution of the UV photocatalysis mechanism. The most important oxidizing species were h+, O2⦁− and ⦁OH, and among them h+ had the greatest impact under solar and visible light irradiation. However, the influence of e- cannot be disregarded. Based on the Aliivibrio fischeri bioluminescence assay a significant influence of the irradiation type on the treated solution toxicity was found.