OSMOTIC DISTILLATION PROCESS FOR CONCENTRATING A LIQUID CONTAINING SODIUM CHLORIDE
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Abstract
Described is an osmotic distillation process for concentrating a liquid containing sodium chloride, and in particular a treatment process for used reaction water containing sodium chloride from the production of polymers.
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Citations
34 Claims
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1-17. -17. (canceled)
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18. An osmotic distillation process for concentrating an aqueous liquid containing sodium chloride, where the liquid has a concentration of up to 20% by weight of sodium chloride, preferably from 2 to 18% by weight of sodium chloride, which comprises at least the following steps,
a) optionally prepurification of the liquid to remove organic secondary constituents, in particular down to a total content of the organic secondary constituents of 20 ppm, b) introduction of the purified liquid into a first zone as evaporation zone which is separated from a diffusion zone adjoining this first zone by a hydrophobic first membrane which is permeable to water vapor, c) diffusion of water vapor from the liquid containing sodium chloride through the membrane into the diffusion zone, d) further diffusion of water vapor from the diffusion zone through a second hydrophobic membrane which is permeable to water vapor into a stripping zone adjoining the diffusion zone and absorption of the water vapor in a draw solution which is continuously replaced in the stripping zone.
Specification