TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Method: The absorption liquid containing organic solvent and/or water is supplied to upper portion of absorption tower maintained at predetermined temperature and pressure. The mixed gas is contacted with absorption liquid, acidic gas is absorbed to absorption liquid, and non-acidic and acidic gas are separated. The non-acidic gas is recovered from absorption tower. The resulting absorption liquid is supplied to regenerator, and acidic gas is liquefied. The liquid acidic gas is separated from absorption liquid by insolubility and specific gravity difference of liquid acidic gas and absorption liquid. The absorption liquid is regenerated and supplied to upper portion of absorption tower. The mixed gas is introduced into chamber (I), and acidic gas is permeated to liquid membrane and supplied to chamber (II). The non-acidic gas remaining in chamber (I) is recovered, and acidic gas is recovered from chamber (II). The mixed gas is dehumidified before supplying to absorption tower and before introducing to membrane separation device. Centrifugation or stirring is carried out before supplying absorption liquid containing acidic gas ejected from absorption tower and cooled at temperature less than temperature of absorption tower, to regenerator. An additive chosen from water, alcohol, phenol and ether is added to absorption liquid. An additive chosen from water, alcohol and ether is supplied to regenerator. The pressure and temperature in regenerator are adjusted. Separation of liquid acidic gas and additive-containing absorption liquid is carried out based on specific gravity difference within regenerator. The additive-containing absorption liquid ejected from separation liquid regenerator is supplied to distil-separating device. The distil-separating device is heated at predetermined temperature, and additive is separated from absorption liquid. A coagulant is added to absorption liquid containing liquid acidic gas in regenerator.Preferred Membrane: A liquid membrane containing absorption liquid impregnated into porous membrane is tensioned in a membrane separation device. The membrane separation device is divided into chamber (I) and chamber (II).Preferred Condition: The absorption tower is maintained at temperature of 0-100degreesC, preferably -30degreesC to 30degreesC and pressure of 1-25 MPa, preferably 4-25 MPa.The regeneration tower is maintained at pressure lower than pressure of absorption tower by 0.1-5 MPa and temperature same or higher than temperature of absorption tower by 30-200degreesC.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Gas: The acidic gas is chosen from carbon dioxide, hydrogen sulfide, carbonyl sulfide, sulfur dioxide, sulfur trioxide, nitrogen oxide, carbon disulfide, hydrogen cyanide, ammonia and mercaptan, preferably carbon dioxide gas. The non-acidic gas hydrogen, methane, carbon monoxide, oxygen, nitrogen and 2-10C hydrocarbon compound.Preferred Liquid: The ionic liquid contains cation chosen from (R,R'-N2C3H3)+(N,N'-dialkyl imidazolium), (NRxH4-x)+(alkyl ammonium), (R-NC5H5)+(alkyl pyridinium), (R-NC4H8)+(N-alkyl pyrrolidinium) and (PRxH4-x)+(alkyl phosphonium), and anion chosen from hexafluorophosphate ion (PF6-), tetrafluoroborate ion (BF4-), nitrate ion (NO3-), ethyl sulfate (EtSO4-), aluminum tetrachloride (AlCl4-) and aluminum tetrabromide (AlBr4-). The absorption liquid is neutral or alkaline.x = 1-3; andR, R' = 1-18C alkyl or hydrogenThe absorption liquid has magnetic characteristics. A magnet is provided at lower portion of separation regenerator.    TECHNOLOGY FOCUS - POLYMERS - Preferred Liquid: The absorption liquid contains polymer chosen from polyethylene glycol, polyvinyl alcohol, polyether, polyester, polyalkyl and polyolefin ion.