(205e) Studies On the Recovery of Polyethylene Glycol From Spent Liquid From Aqueous Two-Phase Extraction

The recovery and recycling of polyethylene glycol (PEG) in spent liquid from aqueous two phase extraction was studied in order to reduce the cost, chemical oxygen demand (COD) discharge, and this will 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 optimum decolorization was reached at the H2O2 concentration of 6%, lasting for 4 hr. Salting out was used for concentration, and the optimum salt is sodium sulphate, at a dosage of 3 grams per 10ml spent liquor. Further, acid washing and alkaline washing was employed for clearing the insoluble impurities. The characteristics of recycled PEG was: appearance of light yellow ; conductivity 10.8µs/cm; freezing point 37-40°C; pH (5% solution) 6.33; and there was no significant difference with commercial PEG.