Photocatalytic removal of SO2 using natural zeolite modified by TiO2 and polyoxypropylene surfactant.

Air pollution due to emission of various hazardous gases such as SO2 into the atmosphere and its control is an important environmental issue. Application of photocatalysts is considered as a suitable process to control the gaseous pollutants. In this study, the efficiency of clinoptilolite as a natural zeolite (Ze) modified by TiO2 (Ze-Ti) and a polymeric surfactant polyoxypropylene (Ze-Ti-POP) for removal of SO2 was investigated. The nanocomposites were characterized by SEM, EDX, and BET analyses. The photocatalytic oxidation experiments of SO2 by the nanocomposites and natural zeolite were done under UV irradiation with initial SO2 concentration of 500 ppm in a photoreactor. The effects of different factors including reaction time, catalyst dose, UV irradiation intensity, humidity content, and calcination temperature and dose of TiO2 were studied. The modification of clinoptilolite by TiO2 and POP increased considerably the BET specific surface area of the nanocomposites. The results showed that maximum removal efficiencies of SO2 by Ze-Ti and Ze-Ti-POP under the optimum experimental conditions were 82.1 and 87.4%, respectively. Adsorption kinetics data well fitted with the Langmuir-Hinshelwood model. Moreover, reusing of nanocomposites after three regeneration cycles indicated that application of Ze-Ti and Ze-Ti-POP nanocomposites could be a promising approach for SO2 removal. Graphical abstract ᅟ.