盐效萃取分离共沸蒸馏后的正丁醇-水混合物

本文利用盐效萃取方法，选择不同无机盐，对超细SiO₂共沸蒸馏后产生的饱和正丁醇-水溶液进行分离，结果表明无机盐溶液可以萃取出正丁醇水溶液中的正丁醇，且萃取效果随无机盐浓度提高而增大，温度对确定质量分数的盐溶液萃取效果影响很小。萃取比小于1.5时，萃取效果随其增大而显著增大；萃取比大于15时，萃取效果随其变化明显变缓。常温下，萃取比R=1.5时，60% K₂CO₃溶液对饱和正丁醇的水溶液的萃取率可达95%以上。有机相通过二次萃取，无机盐质量分数可降至10^-4以下，可回收继续用于共沸蒸馏。K₂CO₃ 溶液的蒸发浓缩次数对萃取效果没有显著影响，表明K₂CO₃溶液具有良好的稳定性，可以满足工业循环使用要求。

Separation by salt extraction of the n-butanol-water system produced in azeotropic distillation

An n-butanol-water solution was separated by salting-out extraction with different inorganic salts. The results showed that inorganic salt solutions could extract n-butanol from aqueous -n-butanol. Extractability increased with increasing salt concentration, and when the salt concentration is constant, temperature had little influence on extractability. When the extraction ratio R was less than 1.5, extractability significantly increased, while when the extraction ratio R was greater than 1.5, extractability changed very slowly. At 20 ℃, when the extraction ratio R was 1.5, the extractability reached 95% with 60% K₂CO₃ solution. The organic phase, in which the mass fraction of salt was less than 10^-4 after carrying out the extraction twice, could be recycled and used in azeotropic distillation. The evaporation time of the K₂CO₃solution had little effect on the extraction, which indicated that the K₂CO₃solution had good stability, and can meet industrial requirements. 