PROCESS FOR RECOVERING CELLULOSE ETHERS FROM AQUEOUS SOLUTIONS VIA ENHANCED SHEAR ULTRAFILTRATION

摘要

The invention relates to a process for recovering cellulose ethers from aqueous solutions, particularly from the washing media obtained in the purification of crude cellulose ethers. The process comprises the following steps: (a) passing the aqueous solution through an ultrafiltration membrane apparatus creating enhanced shear at the surface of the ultrafiltration membrane at a temperature below the flocculation temperature of the cellulose ether; (b) diluting the retentate obtained in step (a) with a solvent in a volume ratio of solvent to retentate in the range of 1:1 to 40:1; and (c) passing the diluted retentate obtained in step (b) through an ultrafiltration membrane apparatus creating enhanced shear at the surface of the ultrafiltration membrane at a temperature below the flocculation temperature of the cellulose ether. The process of the invention provides a good retention of cellulose ether at high membrane fluxes.