Development of a photocatalytic wet scrubbing process for gaseous odor treatment

摘要

In this study, methyl mercaptan (CH 3SH) gas was used to prepare synthetic odorous gases, and a photocatalytic wet scrubbing process as a new approach was developed for treating such odorous gases. In this process, gaseous CH 3SH is first absorbed by the solution, and the dissolved CH 3SH/CH 3S - is then adsorbed onto the solid surface of TiO 2 particles and oxidized under UV illumination in the aqueous phase. Experiments were conducted under different reaction conditions of CH 3SH loading, TiO 2 dosage, and pH. The reaction kinetics of CH 3SH reduction indicates that the pH of the reaction solution greatly influences the rate of CH 3SH absorption by the solution. At pH 11.5, CH 3SH absorption by the solution is the rate-determining step (RDS), whereas at pH 11.5, the photoreaction becomes the RDS in such a system. The experiments demonstrated that the efficiency of CH 3SH degradation determined by two methyl mercaptan sensors and the ratio of odor removal determined by olfactometry measurements can be well maintained at high levels of 95% for a CH 3SH loading of 10 g m -3 h -1. The main intermediates and final products from CH 3SH degradation were identified by GC/MS and ion chromatography, and a pathway for CH 3SH degradation with three routes is proposed and discussed. Odor samples to simulate real foul gases were also prepared and treated with this new process. An electronic nose technique was applied to indentify the patterns of odor characteristics before and after treatment.