Photocatalytic removal of SO 2 using natural zeolite modified by TiO 2 and polyoxypropylene surfactant

Abstract

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

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