High-efficient cyclic absorption of sulfur dioxide in Na-Mg-Ci3- compound system for wet flue gas desulfurization

Sulfur dioxide (SO2), as a primary pollutant in the air, has attracted much attention due to the adverse effects on the atmospheric environment and human health. The wet flue gas desulfurization (WFGD) has been proved to be the most effective method to control the emission of SO2. However, the traditional absorbents in WFGD posed the problems of limited recycling utilization and susceptible to oxidation. In this study, we proposed the Na-Mg-Ci3- compound system to repeatedly absorb SO2 for rounds. The results demonstrated that the compound system can integrate the absorption capacity of Na3Ci absorbent and the regeneration efficiency of Mg3Ci2 absorbent. We compared the performances of the compound systems with different alkaline earth metals (Li, Na, K), and the sodium was most suitable for the circulating desulfurization with the consideration of performance and economy. After that, we investigated the influence of ingredient proportions on the absorbent performance, and the results showed that the 0.4 mol/L Na3Ci and 0.2 mol/L Mg3Ci2 were the best combination for the compound system in these experiments. In this condition, the compound system had the excellent effective sulfur capacity and regeneration speed in the recycling process. Moreover, the anti-oxidation effect of sodium ascorbate was explored, and the reusability performance of compound system can be improved with antioxidants. This study contributes to providing a novel method for the removal and recycling of SO2 in the wet flue gas desulphurization.