A membrane having permselectivity for perchlorate ion is prepared using certain types of quaternary ammonium salts contained in a polymeric matrix material, which may be plasticized. Such membranes are useful in electrodialysis processes, whereby perchlorate-contaminated aqueous compositions are purified.

A carbon molecular sieve (CMS) membrane may advantageously be made by pyrolyzing a membrane precursor composition comprised of a carbon forming polymer (e.g., polyimide) blended with a polyvinylidene chloride copolymer (PVDC), the polyvinylidene chloride copolymer being the reaction product of at least 60% to 97% by weight of vinylidene chloride and at least one other comonomer and the carbon forming polymer to polyvinylidene chloride copolymer has a weight ratio of greater than 1 to 99. The membrane precursor composition may be formed by dissolving the carbon forming polymer and PVDC in a solvent to form a dope solution. The dope solution may be shaped, for example, into an asymmetric hollow fiber. The asymmetric hollow fiber may be heated to a temperature to dehydrochorinate the PVDC and then subsequently heated in a non-oxidizing atmosphere to carbonize the polymers of the shaped membrane to form the CMS membrane.

Magnesium ion selective electrode membranes and the preparation thereof. The membranes are rendered highly selective for magnesium ions by the addition of acidic groups to the preferably PVC membrane, either by introducing a lipophilic compound comprising an acidic group covalently linked to a C4-C18 alkyl-substituted phenyl group (e.g. bis-4-octylphenyl phosphoric acid) into the membrane comprising the magnesium selective ionophore (e.g. a neutral ionophore 1,10-phenanthroline derivative) or by covalently linking an acidic (e.g. a carboxylic) group to the ionophore (e.g. a 1,10-phenanthroline derivative).

A process for separating hydrogen from a gas mixture having hydrogen and a larger gas molecule is comprised of flowing the gas mixture through a carbonized polyvinylidene chloride (PVDC) copolymer membrane having a hydrogen permeance in combination with a hydrogen/methane selectivity, wherein the combination of hydrogen permeance and hydrogen/methane selectivity is (i) at least 30 GPU hydrogen permeance and at least 200 hydrogen/methane selectivity or (ii) at least 10 GPU hydrogen permeance and at least 700 hydrogen/methane selectivity. The carbonized PVDC copolymer may be made by heating and restraining a polyvinylidene chloride copolymer film or hollow fiber having a thickness of 1 micrometer to 250 micrometers to a pretreatment temperature of 100? C. to 180? C. to form a pretreated polyvinylidene chloride copolymer film and then heating and restraining the pretreated polyvinylidene chloride copolymer film to a maximum pyrolysis temperature from 350? C. to 750? C.

The invention provides a porous membrane comprising polyvinyl chloride (PVC) and at least one inorganic filler embedded in the porous membrane wherein the inorganic filler comprises sulfuric acid precipitated silica. The invention further provides a process for the production of said porous membrane.

A composite membrane including an organic polymer matrix and a plurality of porous inorganic particles is disclosed, wherein each of the porous inorganic particles has a plurality of pores arranged while forming a channel in a predetermined direction, and wherein an average length of the porous inorganic particles in a direction parallel to the channel is less than three times the average maximum length of the porous inorganic particles in the direction perpendicular to the channel.

An ion-exchange membrane is disclosed here including ion-permeable layers impregnated with an ion-exchange material and arranged in an order from one face of the membrane to the opposite face of the membrane such that opposing layers in the supporting membrane substrate provide sufficiently identical physical properties to substantially avoid irregular expansion when in a salt solution. The ion-permeable layers including at least one non-woven layer and at least one reinforcing layer.

Provided is a method for preparing a durable hydrophilic ultrafiltration membrane. In the disclosure, a functional hydrophilic molecule is synchronously synthesized during conventional dissolution of a polymer membrane material; and a resulting casting solution (a nascent membrane) is introduced into a coagulation bath, which initiates a cross-linking reaction between the functional hydrophilic molecules to form a hydrophilic cross-linked network. A hydrophilic cross-linked interpenetrating network is formed in situ during polymer phase separation to limit movement of polymer chains and formation and growth of micelles, thereby forming a relatively uniform polymer interpenetrating network structure to obtain the durable hydrophilic ultrafiltration membrane with a relatively uniform membrane pore structure.

Provided is a method for preparing a durable hydrophilic ultrafiltration membrane. In the disclosure, a functional hydrophilic molecule is synchronously synthesized during conventional dissolution of a polymer membrane material; and a resulting casting solution (a nascent membrane) is introduced into a coagulation bath, which initiates a cross-linking reaction between the functional hydrophilic molecules to form a hydrophilic cross-linked network. A hydrophilic cross-linked interpenetrating network is formed in situ during polymer phase separation to limit movement of polymer chains and formation and growth of micelles, thereby forming a relatively uniform polymer interpenetrating network structure to obtain the durable hydrophilic ultrafiltration membrane with a relatively uniform membrane pore structure.

A polymer membrane for water treatment, characterized in comprising a hollow fiber membrane having a self-supporting design composed of the substantially single principal structural material, with an outer diameter of 3.6 mm to 10 mm and a ratio of outer diameter to thickness, SDR, of 3.6 to 34.