Extraction Of Amine Compounds With Imidazolyl Ionic Liquid Of [PF₆]^-

In recent years,ionic liquids have received world wide attention as novel green solvents.Ionic liquids have some unique properties compared with conventional organic solvents,including being liquid over a wide range of temperature,good solvent for many organic and inorganic compounds,no measurable vapor pressure,highly thermally and chemically stable.Therefore, the use of ionic liquids in extraction and separation is very promising.In this work,the extraction of amine compounds has been investigated systematically.The basic physical and chemical properties of ionic liquids and the research on ionic liquid in recent years were summarized.Ionic liquids [Bmim][PF₆],[Hmim][PF₆]and[Omim][PF₆]were synthesized and purified, Their chemical structures are determined by IR and ¹HNMR,respectively.The ionic liquids mentioned above were used as extractants to extract seven kinds of amine compounds respectively from aqueous solution such as aniline,p-chloroaniline.The effects of extraction time,initial concentration of aqueous solvent,phase ratio,added salt,pH,temperature,ionic liquid types on the extraction equilibrium,stages cross-flow extraction and the recovery rate of ionic liquids and aniline were investigated.The results showed that the effect of the initial concentration on distribution coefficient was little.When phase ratio is 10:1,the dissolution of amine compounds in ionic liquids reaches the saturated critical point,and with the increasing of phase ratio which is more than 10:1,the distribution coefficient decreases. The distribution coefficient increases with the addition of salt into the solution such as NaCl and K₂SO₄,but the addition of ZnSO₄ has no influence on the extraction equilibrium.With the increasing of pH,the distribution coefficient increases.During the extraction process,the value of enthalpy increases,it belongs to a endothermic process.After four stages cross-flow extraction,wastewater can reach the discharge standard,the recovery rate of aniline in extraction phase is around 90%,the recovery rate of ionic liquid is above 90%,ionic liquid can be used cyclically.The effect of phase ratio、flow rate and Filler on extraction in packed column were investigated.The results showed when the phase ratio and flow rate increased,the extraction efficiency will be decreased.The extraction efficiency of packing was Cannon ring 3×3＞Cannon ring 6×6＞Raschig ring.