The chemical absorption of sulfur dioxide in aqueous suspension of limestone and DTA studies

In this study, the interaction of sulfur dioxide with limestone was investigated in aqueous suspension. Sulfur dioxide taken from gas cylinder was passed through the mixture of reactive limestone and water, iodine solution. The absorbed and unabsorbed amount of sulfur dioxide on solid and liquid phases and the concentration of Ca2+ and Mg2+ ions were determined by means of iodometric and complexometric respectively. The effects of contact time, the activated temperatures of absorbent and equilibrium pH on the chemical absorption of SO2 were examined. For calcite the maximum amount of absorbed SO2 in the liquid phase was found to be 8.9 g (activated at 600°C), for 10 g absorbent/250 mL water, and in the solid phase, it was found to be 7.5 g (activated at 1000°C). The reaction products were also characterized by the differential thermal analysis (DTA) technique.