Integrated photoreaction of sulfur dioxide (SO2) using Manganese based-TiO2 photocatalyst and choline chloride-ethlene glycol based eutectic ionic liquid

Abstract

Abstract Due to its high toxicity and corrosiveness, sulfur dioxide (SO2) and its products including sulphite and sulphate a type of particulate matter present in air poses a threat to both human health and the environment as an atmospheric pollution. In the current study, an integrated photoreaction was developed for the removal of SO2 from the air stream. First, visible-light responsive TiO2 was synthesized via the precipitation method. Then Manganese (Mn) was additionally added to TiO2 using a wet impregnation process in order to further improve the photocatalyst's efficiency. The eutectic ionic liquid (EIL) based on choline chloride and ethylene glycol (ChCl:E.Gly) was used as an absorbent in the photoreaction. Based on the results of the photocatalytic activity, TiO2_0.1% showed the best performance, with an absorption capacity of 3.39 mmol SO2 equivalent/kg EIL, significantly increasing the SO2 absorption capacity and showing better photocatalytic performance. The photocatalytic process was optimized using central composite design (CCD) and response surface methodology (RSM). A significant integrated SO2 absorption efficiency of 84.4% was obtained at optimal conditions while using (0.25 g/L TiO2 loading, 50 mL EIL, and 0.10 wt% Mn) within 120 minutes of visible-light irradiation. The photoreaction was carried out in a laboratory-scale reactor, and it may be developed locally and would be suitable for industrial scale, providing an effective, affordable, and reliable SO2 collection system.