Method for recycling ion liquid from filature wastewater

Abstract

The invention relates to a method for recycling the ionic liquid in spinning wastewater, which comprises the processes: first, the spinning wastewater is pretreated by precipitating, roughly filtering as well as finely filtering to obtain the pretreatment solution; then, the pretreatment solution is processed by ultrafiltration process to obtain the water solution of the ionic liquid with mass concentration of 0.01-5 percent and the separated cellulose and the cellulose in polyacrylonitrile or the polyacrylonitrile are further processed by ultrafiltration washing and concentration or drying and then the obtained solution is recycled; ultrafiltration membrane of molecular weight cutoff adopted by the ultrafiltration process is 6000-50000 and the operation pressure is 0.01-0.5MPa; the obtained ultrafiltration water solution is further processed by nanofiltration and the reverse osmosis to obtain concentration solution of the ionic liquid with mass concentration of 5-30 percent and removed water after concentration is recycled and reused; the desalinization ratio of the nanofiltration membrane is 50-98 percent and the operation pressure is 0.4-1.0MPa; the desalinization ratio of the reverse osmosis membrane is 98 percent and the operation pressure is 1.0-15MPa; at last, the concentration solution of the ionic solution is decompressed and distilled under 60-110 DEG C to obtain the ionic solution with purity of 95-99 percent.

Description

technical field [0001] The invention relates to a separation membrane application technology, specifically a method for recovering ionic liquids in aqueous solutions by using separation membranes, especially a method for recovering ionic liquids from cellulose or polyacrylonitrile spinning wastewater, International Patent Classification The number is proposed to be Int.Cl.D01F 13 / 02 (2006.01). Background technique [0002] Ionic liquids are usually composed of alkylpyridine or dialkylimidazolium quaternary ammonium cations and tetrafluoroborate, hexafluorophosphate, nitrate, halogen and other anions, which have strong polarity, non-volatility, non-oxidation, good solubility and Most of the reagents are stable and have excellent characteristics. Room temperature ionic liquid, as a new type of green solvent, has been widely studied and applied in spinning cellulose fiber engineering, which has good social benefits. However, due to the high price of ionic liquids, industrial ...

AI Technical Summary

Problems solved by technology

This method consumes a lot of energy, and it is difficult to deal with a large amount of high-quality brine, which brings new problems; Chinese patent CN1804161A discloses a method for recovering ionic liquid in cellulose spinning wastewater, which uses spinning coagulation bath wastewater Through the process of precipitation-filtration-vacuum distillation-atmospheric distillation, the ionic liquid that enters the coagulation bath as a cellulose solvent through wet spinning is effectively recovered

However, due to the low content of ionic liquid in the spinning wastewater, the energy consumption of direct distillation is high, which is not conducive to energy saving and emission reduction

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