双水相萃取废液中成相物质聚乙二醇的回收利用

研究了双水相萃取废液中聚乙二醇的回收利用,旨在降低生产成本,减少COD排放,推动双水相萃取技术的工业应用进程。以聚乙二醇-硫酸铵PEG-（NH4）2SO4]组成的双水相体系废液为原料,采用脱色、浓缩、洗涤除去杂质的工艺技术路线,确定了从双水相废液中回收成相聚合物PEG的最佳工艺（：1）利用H2O2法脱色,最佳脱色条件：H2O2浓度为6%,脱色温度为60℃,脱色时间为4 h,体系pH值为9.0,脱色率达到85%以上（;2）采取盐析法浓缩,最佳电解质种类为Na2SO4,最佳加入量为每10 mL废液3.0 g Na2SO4,此时PEG浓缩比为3.45,PEG损失率为0.31%。按照药用级PEG产品质量标准,对干燥后的回收物进行质量检测。结果表明：回收的PEG产品外观呈浅黄色蜡状,电导率为10.8μs/cm,凝固点为37～40℃,pH值（5%水溶液）为6.33,较纯品PEG无明显差异。

Study on the Recovery of Polyethylene Glycol in Spent Liquid from Aqueous Two-phase Extraction

The recovery and recycling of polyethylene glycol（PEG） in spent liquid from aqueous two phase extraction were studied in order to reduce the cost,chemical oxygen demand（COD） discharge,and precede the application of aqueous two phase extraction in industry.The spent upper phase from the aqueous two-phase system composed of polyethylene glycol（PEG） and ammonium sulfate was used for the recovery of PEG.Hydrogen peroxide（H2O2） was used for decolorization,and the optimal decolorization was reached at the H2O2 concentration of 6%,lasting for 4 h.Salting out was used for concentration,the optimal salt was sodium sulpham,and its optimal amount was 3 g/10 mL spent liquor.Further,acid washing and alkaline washing was employed for clearing the insoluble impurities.The characteristic of recycled PEG was that appearance was light yellow cereus,conductivity was 10.8 μs/cm,freezing point was 37～40 ℃,pH（5% solution） value was 6.33 and there was no significant difference with pure PEG.