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Desulfurization wastewater (DW) can be effectively treated via evaporation using hot flue gas with zero DW discharge. In this study, the characteristics of HCl release and SO 2 /NO 2 absorption were investigated during DW evaporation based on an experimental spray drying system. The results indicated that increasing the pH of DW effectively inhibited HCl release by inhibiting the acidification of water and hydrolysis of chloride. At high pH, regardless of changes in operational parameters, the HCl release ratio remained less than 4.0%. Additionally, DW with high pH also absorbed SO 2 and NO 2 during evaporation, and its SO 2 absorption efficiency was greater than its NO x absorption efficiency. The main parameters inhibiting HCl release ratio, i.e., higher pH, higher Cl − concentration in DW, and lower flue gas temperatures, also promoted SO 2 /NO 2 absorption. However, by adding excess Ca(OH) 2 to DW, the absorption of the acidic pollutants did not increase the release of HCl during DW evaporation. Under the operational parameters of the reference experiment, the absorption efficiencies of SO 2 and NO x were 35.6% and 16.2%, respectively, and the corresponding HCl release ratio was approximately only 1.1%.

Ionic liquid desulfurization is an effective method for achieving green and circulating desulfurization. To overcome the negative impact of the high viscosity of ionic liquids on the desulfurization process, an economical and efficient supported ionic liquidtriethanolamine acetate ionic liquid/silica (TAIL/SiO2) was prepared in this study. TAIL is synthesized using triethanolamine and acetic acid and subsequently loaded onto silica gel particles. The effects of the reaction temperature, humidity, silica particle size, and loading ratio on SO2 adsorption are investigated using a fixed-bed reactor. The results indicate that the surface of the silica gel loaded with ionic liquid formed uneven spherical clusters, and the aggregate volume increased with an increase in the loading ratio. The TAIL/SiO2 sulfur capacity could be effectively increased by increasing the loading ratio (exceeding 0.74 is unfavorable), decreasing the silica particle size, and reducing the reaction temperature and moisture content. The maximum sulfur capacity can reach 124.98 mg SO2/(g TAIL/SiO2) under experimental conditions, which is higher than that of activated carbon. The Bangham rate model effectively predicts the kinetics of the adsorption process of SO2.

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