Composite RO membranes having good resistance to halogen attack and high fluxes are disclosed, the composite membranes comprising a microporous polymeric support with an interfacially polymerized salt-rejecting layer thereon comprising an aromatic aliphatic diamide/diimide.

Composite RO membranes of a microporous polymeric support and a polyamide reaction product of a tetrakis-aminomethyl compound and a polyacylhalide are disclosed, said membranes exhibiting high flux and good chlorine resistance.

Composite RO membranes having good resistance to halogen attack and extraordinarily high fluxes are disclosed, the composite membranes comprising a microporous polymeric support with an interfacially polymerized salt-rejecting layer thereon comprising an aromatic aliphatic diamide/diimide.

An asymmetric microporous membrane with exceptional solvent resistance and highly desirable permeability is disclosed. The membrane is made by a solution-casting or solution-spinning process from a copolyamic acid comprising the condensation reaction product in a solvent of at least three reactants selected from certain diamines and dianhydrides and post-treated to imidize and in some cases cross-link the copolyamic acid. The membrane is useful as an uncoated membrane for ultrafiltration, microf...

A process for removing and recovering a condensable vapor from a gas stream by a membrane contactor is disclosed wherein a gas stream containing a condensable vapor is circulated on one side of hollow fiber membranes while cool extraction fluid is circulated on the other side under a total pressure differential, thereby condensing the condensable vapor in the gas stream, the condensed vapor permeating the membrane and becoming entrained in the cool extraction fluid.

A process for improving both the internal burst strengths and gas and water permeabilities of certain microporous polymeric hollow fibers useful in RO applications comprises a wet annealing process for certain such fibers.

A gas dehydration method and apparatus are disclosed which utilize lumen-side feed, hydrophilic polymer-inside-coated, thin-film composite hollow fiber membranes, the support fiber of which is highly permeable, such composite membranes being used in a module wherein the permeate flows countercurrent to the flow of the feed, and in which dried raffinate gas is mixed with water-containing permeate at a point opposite the feed end of the module.

A vapor permeation method and apparatus for removing a vapor from a vaporous feed stream, the method and apparatus utilizing highly solvent-resistant composite hollow fiber membranes and a permeate flow countercurrent to the feed flow, wherein the support of the composite membrane is formed by solution casting and has been rendered sufficiently solvent-resistant by a post-casting step to retain at least 20 of its burst pressure when soaked in the solvent used to cast the support.

Improved methods of rendering PVDF membranes hydrophilic are disclosed.

There is described a process for the removal of at least one component of a liquid mixture, the basic process comprising directing a liquid mixture against the feed side of a membrane, directing a condensable vapor sweep stream past the permeate side of the membrane in a manner such that the flow of the condensable vapor sweep is substantially countercurrent to the flow of the liquid mixture, thereby transporting at least a portion of at least one component of the liquid mixture from the feed si...