BACKGROUNDSO(2) is an important gaseous pollutant that seriously affects the environment and human health. The most common method for SO2 removal is absorption by NaOH solution and then forming HSO3-. Since generation of high-value products and reduction of alkali consumption are important for the economy and practical application, selenium-catalyzed HSO3- disproportionation was developed in this study. RESULTSSelenium decreased the reaction temperature of HSO3- disproportionation from >433K to 343K. The effects of HSO3- concentration, temperature, selenium dosage, and stirring intensity were investigated. Selenium could be used at least five times with stable catalytic performance, indicating satisfactory reusability. More importantly, a catalytic mechanism was proposed using dynamic light scattering, differential scanning calorimetry and UV-visible transmittance spectrophotometry. Results showed that selenium-catalyzed HSO3- disproportionation experienced a solid-liquid-solid phase transformation process. During this process, SeSO32- and HSe- were identified as the intermediates. Furthermore, products, i.e. sulfur and sodium bisulfate, were characterized to demonstrate their structure and composition. CONCLUSIONSelenium was an efficient catalyst for HSO3- disproportionation. This catalytic process offered the advantages of less consumption of alkali and production of high-valuable products, and thus was a potential alternative to other technology for SO2 removal in practical applications. (c) 2015 Society of Chemical Industry