Gas separation membrane drying with water replacement liquid
First Claim
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1. In the process for drying a semipermeable polymeric membrane that is wet with an aqueous membrane-wetting liquid by contacting the wet membrane with at least one water replacement liquid inert to the membrane and to the membrane-wetting liquid to remove water from the membrane, and removing the replacement liquid from the membrane;
- the improvement which comprises contacting said wet polymeric membrane in which the polymer has a Critical Surface Tension of at least about 42 dynes per centimeter, at a temperature of about from 0°
to 50°
C. with a water replacement liquid consisting essentially of at least one organic solvent which is selected from the group consisting of aliphatic alcohols having 4-8 carbon atoms, aliphtic aldehydes having 3-8 carbon atoms and aliphatic ketones having 3-8 carbon atoms, carboxylic acids, carboxylic esters having 4-8 carbon atoms, aliphatic nitriles, ethers, acetals, ketals, amines, halocarbons having 1-3 carbon atoms and containing at least one hydrogen atom, and aqueous solutions thereof, said solvent having a surface tension at 20°
C. of not more than about 35 dynes per centimeter, a viscosity less than about 10 centipoise, a molar volume less than about 200 cubic centimeters per mole at 20°
C, a solubility for water not greater than about 20 weight percent at the contacting temperature, and a hydrogen bonding parameter of at least about 1 (calorie per cubic centimeter)1/2 ; and
after water has been substantially completely removed from the membrane, evaporating the replacement liquid to obtain a membrane free of water and replacement liquid.
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Abstract
Process for drying a water-wet permselective membrane by initially contacting the membrane with water replacement liquid having low surface tension and limited solubility for water.
43 Citations
5 Claims
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1. In the process for drying a semipermeable polymeric membrane that is wet with an aqueous membrane-wetting liquid by contacting the wet membrane with at least one water replacement liquid inert to the membrane and to the membrane-wetting liquid to remove water from the membrane, and removing the replacement liquid from the membrane;
- the improvement which comprises contacting said wet polymeric membrane in which the polymer has a Critical Surface Tension of at least about 42 dynes per centimeter, at a temperature of about from 0°
to 50°
C. with a water replacement liquid consisting essentially of at least one organic solvent which is selected from the group consisting of aliphatic alcohols having 4-8 carbon atoms, aliphtic aldehydes having 3-8 carbon atoms and aliphatic ketones having 3-8 carbon atoms, carboxylic acids, carboxylic esters having 4-8 carbon atoms, aliphatic nitriles, ethers, acetals, ketals, amines, halocarbons having 1-3 carbon atoms and containing at least one hydrogen atom, and aqueous solutions thereof, said solvent having a surface tension at 20°
C. of not more than about 35 dynes per centimeter, a viscosity less than about 10 centipoise, a molar volume less than about 200 cubic centimeters per mole at 20°
C, a solubility for water not greater than about 20 weight percent at the contacting temperature, and a hydrogen bonding parameter of at least about 1 (calorie per cubic centimeter)1/2 ; and
after water has been substantially completely removed from the membrane, evaporating the replacement liquid to obtain a membrane free of water and replacement liquid. - View Dependent Claims (2, 3, 4, 5)
- the improvement which comprises contacting said wet polymeric membrane in which the polymer has a Critical Surface Tension of at least about 42 dynes per centimeter, at a temperature of about from 0°
Specification