MgSO_4和Li_2SO_4对乙醇-水体系互溶性的影响

测定了 Mg SO4- C2 H5 OH- H2 O三元系在 - 5℃ ,0℃ ,30℃ ,35℃及 5 0℃和 L i2 SO4- Mg SO4- C2 H5 OH- H2 O四元系在 2 5℃的互溶度和相关系。结果表明 :Mg SO4可使完全互溶的乙醇 -水体系分层 ,且 Mg SO4在两层液相中的含量明显不同。L i2 SO4和 Mg SO4作为混合盐在乙醇 -水体系中的行为表现出加和性。L i2 SO4本身在室温范围下不会使乙醇 -水体系分层 ,但适量的 L i2 SO4与 Mg SO4混合可使乙醇 -水体系的分层温度从33℃下降至 15℃以下。另一方面 ,乙醇的存在不仅可以降低 Mg SO4和 L i2 SO4的溶解度 ,而且可促成 Mg SO4· 7H2 O的脱水。该三元系中 Mg SO4的溶解度随温度升高而增大 ,在乙醇中几乎不能溶解。在 30℃ ,35℃和 5 0℃下体系的平衡固相为 Mg SO4· 6 H2 O,其他温度下是 Mg SO4· 7H2 O。提出一个经验公式对互溶性进行了关联 ,效果很好

The Effect of MgSO4 and Li2SO4 on Solubility of Ethanol-Water System

The solubility and phase relations for ternary system MgSO 4 C 2H 5OH H 2O at -5℃,0℃,30℃,35℃ and 50℃,and for quaternary system MgSO 4 Li 2SO 4 C 2H 5OH H 2O at 25℃ have been determined.The results prove that MgSO 4 is capable of layering the miscible ethanol water system,and the content of MgSO 4 in two liquid layers is considerably different.As a mixed salt,MgSO 4 and Li 2SO 4 reveals addition property in the mixed solvent C 2H 5OH H 2O.With a proper amount of Li 2SO 4 mixed with MgSO 4,the layering temperature for ethanol water drops from 33℃ to under 15℃ though Li 2SO 4 can not layer it at around room temperature.On the other hand,ethanol enables to reduce the solubility of MgSO 4 and Li 2SO 4,and to dehydrate MgSO 4·7H 2O.The solubility of MgSO 4 in the ternary system grows with the temperature raising,but MgSO 4 can hardly be dissolved in pure ethanol.The equilibrium solid phase for the ternary system at 30℃,35℃ and 50℃ are MgSO 4·6H 2O and MgSO 4·7H 2O at other two temperatures.An empirical formula has been proposed for correlating the solubility,which gives satisfactory results.