盐效萃取分离共沸蒸馏后的正丁醇-水混合物

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

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。

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% K2CO3solution. The organic phase,in which the mass fraction of salt was less than 10- 4after 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.