Abstract: A non-cracking hydrophilic polyether sulfone membrane is prepared by (a) directly coating the entire surface of a hydrophobic polyethersulfone membrane with an aqueous solution of a polyalkylene oxide polymer and at least one polyfunctional monomer, and (b) polymerizing the monomer over the entire surface of the membrane under conditions which cause the resulting polymer to attach to the polyethersulfone membrane and the polyethylene oxide to form a non-extractable surface which does not crack when the membrane is folded to form a pleated cartridge.

Abstract: A non-cracking hydrophilic polyether sulfone membrane is prepared by (a) directly coating the entire surface of a hydrophobic polyethersulfone membrane with an aqueous solution of a polyalkylene oxide polymer and at least one polyfunctional monomer, and (b) polymerizing the monomer over the entire surface of the membrane under conditions which cause the resulting polymer to attach to the polyethersulfone membrane and the polyethylene oxide to form a non-extractable surface which does not crack when the membrane is folded to form a pleated cartridge.

Abstract: A non-cracking hydrophilic polyether sulfone membrane is prepared by (a) directly coating the entire surface of a hydrophobic polyethersulfone membrane with an aqueous solution of a polyalkylene oxide polymer and at least one polyfunctional monomer, and (b) polymerizing the monomer over the entire surface of the membrane under conditions which cause the resulting polymer to attach to the polyethersulfone membrane and the polyethylene oxide to form a non-extractable surface which does not crack when the membrane is folded to form a pleated cartridge.

Abstract: A method for making a skinless essentially symmetrical hydrophobic polysulfone microporous membrane by the steps of (a) forming a casting solution containing (i) a dissolved polyethersulfone polymer, (ii) a solvent for the polyethersulfone polymer, and (iii) a lower aliphatic glycol; (b) coating a substrate with the casting composition; (c) exposing the coated substrate to atmospheric conditions; (d) passing the exposed coated substrate into a precipitation bath to precipitate the membrane, the precipitation bath containing a lower aliphatic glycol and water; (e) rinsing the membrane; and (f) drying the membrane.

Abstract: Polyamide (nylon) microporous membranes are prepared from a polyamide (nylon) polymer which contains aromatic rings, aliphatic carbon chains, and amide groups. The membranes exhibit improved long term performance characteristics.

Abstract: A reverse osmosis water purification system has a feed water line and outlets for reject and product water. Instead of wasting the reject water by allowing it to flow to a drain, the reject water is returned to the water feed line downstream of the reverse osmosis system so that is can be used for other purposes. A section of the water feed line has a flow restrictor which estabishes a dynamic pressure drop. Feed water for the reverse osmosis system is taken off the feed line upstream of the restrictor and reject water is returned downstream of the restrictor, thereby reducing the water wastage due to the reverse osmosis process.