基团贡献法推算有机混合液体表面张力

本文在作者曾经提出的推算液体混合物表面张力计算方法的基础上,考查了不同纯组分摩尔表面积的计算公式对液体混合物表面张力推算精度的影响.通过对100个二元体系、10个三元体系和2个四元体系的推算,找到了合适的计算公式.二元体系、多元体系的推算偏差分别为2.45%和4.42%,对于非含一元醇-水体系,式(3)为好,其偏差为2.45%,对含一元醇-水体系式(6)有明显的改善,其推算偏差为6.98%.

PREDICTION OF THE SURFACE TENSION OF ORGANIC LIQUID MIXTURES BY GROUP CONTRIBUTION METHOD

In an earlier study, we proposed a new method in which the surface tensionsof mixtures of organic non-electrolytes are predicted successfully by the well-kn own UNIFAC group contribution method used in phase equilibrium calculations. In this paper, four different molar surface area equations are investigated with respect to precision of surface tension prediction by the use of our proposed method of applying UNIFAC model. Different molar surface area equations are given as:Ai=Ai = ViB2/3NA1/3 (1)Ai=Ai = 1.21ViB2/3NA1/3 (2)Ai=Ai = ViB4/15Vic2/5NA1/3 (3)Ai=Ai = 1.21ViB4/15Vic2/5NA1/3 (4)where Ai and Ai are the molar surface area and the partial molar surface area of component i respectively, ViB is the liquid molar volume of pure component i, NA is Avogadro's number, and Vic is the critical molar volume of component i.The surface tensions of 100 binary, 10 ternary and 2 quaternary systems are calculated with the above equations. Comparing calculated values vith experimental data, we conclude that equation(4) is the best for the systems containing both water and alcohols. The total average relative deviations from experiment are 6.98% for 6 systems containing both water and alcohols. These results are satisfactory for engineering design.