Membrane drying process

• US 4,080,743 A
• Filed: 06/22/1976
• Issued: 03/28/1978
• Est. Priority Date: 06/22/1976
• Status: Expired due to Term

• Current Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Original Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Inventors: Manos, Philip
• Primary Examiner(s): Spear, Jr., Frank A.
• Application Number:
  US05/698,696
• Time in Patent Office: 644 Days
• Field of Search: 210/500 M, 210/23 H, 210/321 R, 55/16, 264/41, 264/330, 264/340, 264/344, 34/9, 260/2.5 A
• US Class Current: 34/342
• CPC Class Codes: B01D 12/00 Displacing liquid, e.g. from wet solids or from dispersions of liquids or from solids in liquids, by means of another liquid
• CPC Class Codes: B01D 67/0095 Drying

Abstract

Process for drying a water-wet membrane by contacting with a solution of water miscible and water immiscible solvents and then removing the solution.

Claims

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 replacement liquid to remove water from the membrane, and removing the replacement liquid from the membrane;

the improvement which comprises first contacting the wet semipermeable polymeric membrane in which the polymer has a Critical Surface Tension of at least 42 dynes per centimeter with at least one replacement liquid consisting essentially of a homogeneous solution of (a) a major portion of at least one organic solvent selected from the class consisting of hydrocarbons having 4-8 carbon atoms and perchlorofluorocarbons having 1-3 carbon atoms and (b) a minor portion of at least one organic solvent substantially miscible with water having a hydrogen bonding parameter of at least about 1.5 (calories per cubic centimeter)^1/2 , wherein the components of the replacement liquid each exhibit, at 20°

C, a viscosity of less than about 10 centipoise and a molar volume of less than about 200 cubic centimeters per mole; 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.

3. A process of claim 1 wherein the water-wet membrane is an asymmetric membrane having a dense skin on one surface thereof.

4. A process of claim 1 wherein the semi-permeable membrane is selected from nitrogen-linked aromatic polymers, sulfonated poly(arylene ether sulfones), and sulfonated poly(phenylene oxides).

5. A process of claim 1 wherein the major portion of the homogeneous solution consists essentially of 1,1,2-trichloro-1,2,2-trifluoroethane and the minor portion of the homogeneous solution consists essentially of methanol.

6. A process of claim 5 wherein the resulting liquid-wet membrane is subsequently contacted with substantially pure 1,1,2-trichloro-1,2,2-trifluoroethane and the 1,1,2-trichloro-1,2,2-trifluoroethane is removed by evaporation.

2. A process of claim wherein the water miscible solvent comprises about from 2% to 10% of the homogeneous solution.