Reversible absorption of SO2 from simulated flue gas by aqueous calcium lactate solution

• Aqueous calcium lactate solution can absorb SO2 efficiently.
• The absorption of SO2 by aqueous calcium lactate solution is reversible.
• The oxidation product CaSO4 can be easily separated from the absorbent.
• An efficient and economical way to absorb and recover SO2 is proposed.

The capture of SO2 by recyclable absorbents has drawn much attention all over the world. In this work, it was found that aqueous calcium lactate (CaL2) solution can be used as a recyclable absorbent for the capture of SO2. The solution shows high SO2 absorption capacities up to 24.8 g SO2/kg absorbent at 40 °C. The effects of temperature, excessive lactic acid and CaL2 concentration on the absorption of SO2, the desorption of SO2, and the reuse of aqueous CaL2 solution were systemically studied. Furthermore, the difference between CaL2 method and traditional calcium method was discussed. Compared with traditional calcium method, there are some advantages, such as regeneration of absorbent, recovery of SO2 and reduction of CaSO4. This work suggests that aqueous CaL2 solution, which can be obtained at quite low cost, is a promising recyclable absorbent in the process of desulfurization of flue gas.

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