CO2 RECOVERY FROM FLUE-GAS BY AN ECOTECHNOLOGICAL (ENVIRONMENTALLY FRIENDLY) SYSTEM

A new wet system to treat carbon dioxide in hue gas using water as an absorbent and soil as a cation-exchanger is proposed. The system consi sts of the following four processes. (i) Dissolution occurs of CO2 fro m the flue gas into soil-containing water and is accompanied by format ion of carbonate ions and an increase in the pH of the solution. Soil functions as a cation-exchanger because it is rich in alkaline-earth-m etal ions. (ii) The CO2 increase results in enhancement of hyrogen-ion and alkaline-earth-metal ion exchanges. (iii) Separation of the soil and aeration of the solution takes place. (iv) Carbonate-ion and alkal ine-earth-metal ion reactions form carbonate salts, which are insolubl e in water. The remaining solution is not toxic and does not damage th e environment. It can be reused in the system or released into a river or the ocean. Our wet system is expected to be applied in developing countries because (a) inexpensive soil can be used as the cation-excha nger, (b) the discharged solution is harmless to nature and (c) insolu ble carbonates may be used commercially. Copyright (C) 1996 Elsevier S cience Ltd.