加盐萃取精馏法回收制药废液中乙醇

为了从制药工业得到的乙醇废液中回收无水乙醇,研究了不同浓度的醋酸钾、氯化钙、碳酸钾及醋酸钾-氯化钙混合盐与乙二醇组成的萃取体系对乙醇-水体系分离效果的影响,并考察了溶剂比以及萃取剂和乙醇流速等操作参数对乙醇-水体系精馏分离效果的影响,开发了乙醇废水精馏制备恒沸乙醇、加盐萃取精馏制备无水乙醇和萃取剂回收为一体的无水乙醇回收体系.结果表明:采用乙二醇-醋酸钾-氯化钙三元体系组成的萃取剂,当醋酸钾的浓度为0.025 g/mL,氯化钙的浓度为0.025 g/mL,溶剂比1.2,回流比1.5,乙二醇的流速1.0 mL/min,恒沸乙醇的流速1.2 mL/min时,可以从塔顶得到质量分数大于99.8%的无水乙醇.与文献[4]相比,回流比由2.0降低为1.5,从而大大降低了乙醇回收成本.

The Recovery of Ethanol from Pharmaceutical Waste Liquid by Salt-adding Extractive Distillation

In order to recover anhydrous ethanol from pharmaceutical waste liquor,the effects of different concentration of potassium acetate-ethylene glycol,calcium chloride-ethylene glycol,potassium carbonate-ethylene glycol,potassium acetate-calcium chloride-ethylene glycol system on the distillation separation efficiency of ethanol-water system were studied.The effects of solvent ratio,flow rate of extractant and water-containing ethanol on the distillation separation efficiency of ethanol-water system were also investigated.Azeotropic ethanol was prepared by distillation of ethanol wastewater,and anhydrous ethanol was prepared by salt-adding extractive distillation and extractant recovery was integrated into an anhydrous ethanol recovery system.The results showed that when the concentration of potassium acetate and calcium chloride was 0.025 g/mL,the solvent ratio was 1.2,the reflux ratio was 1.5,and the flow rate of ethylene glycol was 1.0 mL/min,and that when the flow rate of azeotropic ethanol was 1.2 mL/min,anhydrous ethanol with mass fraction greater than 99.8%could be obtained from the top of the tower.Compared with reference[4],the reflux ratio decreased from 2.0 to 1.5,which greatly reduced the cost of ethanol recovery.