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Manufacture of cellulose ethers usually involves high amounts of salt by-products. For application of the product, salt must be removed. In this work, we have studied the injection of high-pressure C02 into an aqueous polymer-salt solution; we find that upon addition of isopropanol in addition to C02, the solution separates into two phases. One phase is rich in polymer and water, and the other phase contains mostly isopropanol, water and CO 2. The salt distributes bet_ecn the two phases, thereby offering interesting possibilities for development of a new purification process for water-soluble polymers. This work presents cxperim,'ntal phase-equilibrium data for hydroxyethvl cellulose and sodium carboxymethyl cellulose with sodium acetate and potassium sulfate, respectively, in the region 40°C and 30 to 80 bar. Based on these d:_',a, _c suggest a process for the manufacture and purification of water-soluble cellulose ethers.. ',UILIIIILILII_ IdLIUUI L]U/DU. i!! ,tdditit)n, tilt viscosity of aqueous HEC samples is lower tlaan