Group Contribution Method For Ionic Liquid Properties And SO₂ Absorption

Group contribution is the effective method to predict the physicochemical properties of compound.It is widely applied in the system of pure substance and mixed property estimation.Compared with other methods,the group contribution method has a wide range of application.And with the computer combination,the forecast process is more simple and versatility.In this paper,the topic is based on group contribution to established the prediction equation of ionic liquid absorbing SO₂,and reverse design a new type of ionic liquids with high absorption,and determine properties of the ionic liquid and the SO₂ absorption.The major conclusions are as follows:36 typical ionic liquids has been selected in this experiment,and The ILs was split out 25 groups to optimized.At T = 303.15 K,the contribution values of each cation from small to large order is: TMG+< MIm+< Py+< N+< P+;Anion is arranged as follows:MeSO3-< Im-< TE-< PHE-< SCN-< MeSO4-< OAc-< L-< C?CN?3-< Tetz-< BF4-< Tf2N-< PF6-< diglutarate-.Lingo program was used to optimization,while the groups had been restructured.Considering the contribution value,the cost of raw materials and test the ease of operation,the final optimization of the ionic liquid [Et2NEMim] [SCN] and [C2OHMim][SCN] have higher absorption to SO₂.At 298.15 K,SO₂ absorption of ionic liquid [Et2NEMim][SCN] and [C2OHMim][SCN] were 1.207 g SO₂/g IL,0.649 g SO₂/g IL.SO₂ absorption and temperature is nonlinear relationship,and it can expressed by cubic polynomial equation.Comparison the experimental value and the calculated value,it was found that the average absolute deviation is about 2.07%.So using the group contribution to prediction ionic liquid of SO₂ absorption has certain credibility.The relation of the temperature and the density is in line with a linear equation and the temperature dependant viscosity and conductivity is described by a VTF equation.VE of ionic liquid aqueous solution and the molar ratio of water are well fitted by a fourth order Redlich-Kister equation.?? with water content are well fitted by a fifth order Redlich-Kister equation.The conductivity of ionic liquid aqueous solution and the molar ratio of water was described to Castell-Amis equation.At 303.15 to 343.15 K,the SO₂ absorption of ionic liquids with 5% water content is higher than the pure ionic liquids.