Water absorption and photocatalytic activity of TiO2 in a scrubber system for odor control at varying pH

The water absorption and photocatalytic activity of TiO2 in a novel scrubber system for odor control using CH3SH gas as target compound was investigated. It was found that the amount of absorbed CH3SH in water increased with increasing initial pH of water, especially in basic water, which was approximately four times than those in acid and neutral water. Adding TiO2 into water had little influence on the dissolved property of CH3SH in water with different pH. TiO2 exhibited excellent photocatalytic activity in the scrubber system for CH3SH removal and reaction solution with high pH facilitated the photocatalytic degradation of CH3SH. In basic TiO2 suspensions, 96.3% of dissolved CH3SH was degraded and the pseudo-first-order kinetic constant was roughly 1.5 and 2.7 times of those obtained in neutral and acid TiO2 suspensions, respectively. Role of TiO2 on CH3SH degradation in water was also discussed. Furthermore, the outlet concentrations of CH3SH all decreased to nearly zero after 60 min of UV light irradiation in TiO2 suspensions with different pH. Varieties in the pH of water and TiO2 suspended solution after absorption and degradation process were measured. The absorption capacity of basic water with addition of TiO2 was relatively stable and TiO2 kept high photocatalytic activity for a long time (900 min). This study provided helpful information on expanding the photocatalytic scrubber system for practical odor treatment.

► Wet scrubbing and TiO2 photocatalysis are combined properly for odor control. ► TiO2 exhibits superior photocatalytic activity in degrading CH3SH. ► High solution pH favors absorption of CH3SH and reaction of h+ with OH−. ► Basic TiO2 suspension shows stable absorption ability and photocatalytic activity.