苯,环己烷,N,N-二甲基甲酰胺和硫氰酸钾四元体系液液平衡测定及关联

Liquid-Liquid Equilibria Determination and Correlation for Systen of Benzene + Cyclohexane + N,N-dimethylformamide + Potassium Thiocyanate

以正丁醇为内标物,用气相色谱测定了苯＋环己烷＋N,N-二甲基甲酰胺（DMF）＋硫氰酸钾（KSCN）四元体系在大气压下,298.15 K和303.15 K时的液液平衡数据。通过平衡数据计算了DMF＋KSCN混合萃取剂对苯的选择性系数和分配系数,该混合萃取剂选择性系数范围为1.5~10.3。实验结果表明,选择性系数随着萃余相中苯含量的增大而减小;随着混合溶剂中KSCN含量的增加而增大。平衡数据采用Othmer-Tobias方程进行关联,计算的Othmer-Tobias方程的标准偏差为0.05~0.09,相关系数接近于1,说明该关联式可以很好的描述实验数据。鉴于DMF＋KSCN混合溶剂表现出较高的选择性,该溶剂可作为一种潜在的萃取剂用于分离苯和环己烷混合物。

Experimental liquid-liquid equilibrium （LLE） data were measured for system of benzene ＋ cyclohexane ＋ N,N-dimethylformamide （DMF） ＋ potassium thiocyanate （KSCN） at normal atmospheric pressure and （298.15, 303.15） K by using gas chromatography which the n-butyl alcohol was used as internal standard. The selectivity coefficients of DMF＋KSCN for benzene ranged from 1.5 to 10.3 in this work. The results reveal that the selectivity coefficients increase with the decreasing of the concentration of benzene in the raffinate, and increase with the increasing content of KSCN in DMF＋KSCN mixture. The experimental data were correlated by using the Othmer-Tobias correlation. The Othmer-Tobias model represents the experimental data with sufficient accuracy with the values of correlation factor R2 close to 1.0 and the values of the root mean square error range from 0.05 to 0.09. Considering the high selectivity for benzene, DMF＋KSCN may be used as a potential extraction solvent for the separation of benzene and cyclohexane mixtures.