Abstract: High quality reverse osmosis, nanofiltration, and ultrafiltration membranes are produced by a high speed process wherein the membranes which have excellent rejection characteristics coupled with high flux capabilities. The process employs tandem coating techniques to coat a microporous substrate with a thin membrane on the order of 25 Å to 1.0 microns. The tandem coating process comprises tandem offset gravure and subsequent slot die coating applicators, or alternatively comprises tandem slot die coating applicators. For reverse osmosis and nanofiltration membranes, a wet-on-wet coating process is used to coat a porous substrate first with an aqueous solution, and then with an organic solution to produce a cross-linked, interfacially polymerized composite membrane. Single slot coating applicators are utilized to produce ultrafiltration membranes.

Abstract: A process for producing high quality reverse osmosis, nanofiltration, and ultrafiltration membranes in a high speed process provides membranes which have excellent rejection characteristics coupled with high flux capabilities. The process employs tandem coating techniques to coat a microporous substrate with a thin membrane on the order of 25 .ANG. to 1.0 microns. The tandem coating process comprises tandem offset gravure and subsequent slot die coating applicators, or alternatively comprises tandem slot die coating applicators. For reverse osmosis and nanfiltration membranes, a wet-on-wet coating process is used to coat a porous substrate first with an aqueous solution, and then with an organic solution to produce a cross-linked, interfacially polymerized composite membrane. Single slot coating applicators are utilized to produce ultrafiltration membranes.

Abstract: A method for constructing a polyvinylidene fluoride based hollow fiber membrane from a polymer mixture using temperatures not greater than 80.degree. C., the mixture comprising polyvinylidene fluoride, a pore forming agent, and a solvent. The mixture can also comprise a second polymer selected from the group comprising polymethylmethacrylate, polyvinylformal, polyvinyl alcohol, polyhexafluoropropylene, polydiacetylene, cellulose and copolymers thereof. The hollow fiber membranes formed using the controlled temperatures of this invention have acceptable strength characteristics and asymmetrical pore structures which provide a low transmembrane pressure drop.

Abstract: A method for preparing a spiral wound filtration module is provided. The module has a central permeate carrier tube. The method includes winding at least one filtration leaf about the permeate carrier tube. The filtration leaf includes a first membrane sheet, a permeate carrier sheet, and a second membrane sheet. The winding step creates an end face extending radially outwardly from the permeate tube on each end thereof. After winding, the filtration module is maintained in a wound state. An adhesive is then supplied to each end face and a vacuum is applied through each of the permeate tube. While the vacuum is applied, the permeate tube and filtration leaf assembly are spun in a centrifuge until the adhesive has solidified. After spinning, each end face of the module is severed at a distance between the level of adhesive along the feed spacer screen and the level of adhesive along the permeate carrier sheet.

Abstract: A process for forming a dialysis membrane utilizing a mixture of ion exchange resin components and thermoplastic resin components mixed together in a dry state and rotationally formed into a membrane. The rotational forming process includes rotational molding using temperature to conform the components to the shape of the mold as well as rotational casting using solvents and phase inversion to form the membrane. The resulting membrane is a smooth, dimensionally stable, efficient dialysis membrane.

Abstract: An electrode apparatus for dialysis of a liquid during electrodeposition processes includes an elongated body submergible in the liquid and having a generally open interior for receiving an elongated electrode therein. An ion exchange membrane forms a portion of the body and permits a filtrate to flow from the liquid through the membrane and enter the open interior of the body. An anolyte enters the body through an anolyte inlet, and an anolyte outlet removes anolyte and filtrate from the body. An electrical cable or conductor is joined to the electrode at a connection within the body to provide an electrical charge to the apparatus. A liquid-tight chamber formed within the body contains the electrical cable and electrode connection and retains them in liquid isolation from the anolyte and filtrate within the body as well as from the liquid within the electrodeposition container. Access is provided to the chamber to permit servicing of the connection.

Abstract: A membrane filtration module is provided incorporating a seal assembly to seal the annular space or bypass channel existing between the outer diameter of the filtration cartridge and the inner diameter of the housing in which it is disposed. The seal assembly prevents a feed stream from entering the bypass channel, and includes a pair of seals each having a flexible gasket and a sleeve extending perpendicularly therefrom, the sleeve being adapted to be positioned directly on the cartridge. This positioning prevents the feed stream from ever coming into contact with the housing.

Abstract: A membrane useful as an ultrafiltration or reverse osmosis membrane is formed from the casting onto a substrate such as a porous polyester sheet a material comprising an epoxy- or trimethylene ether-direct grafted halogenated vinyl polymer prepared by the reaction of an epoxide such as a 5-ethyl,5'-methyl-hydantoin/epichlorohydrin condensation product with a halogenated vinyl polymer such as polyvinylidene fluoride in the presence of a metal halide catalyst. The ether residue of the epoxide or trimethylene-containing group is grafted directly to the first carbon-chain carbon of the halogenated vinyl polymer.

Abstract: An epoxy or trimethylene ether-direct grafted halogeneated vinyl polymer is prepared by the reaction of an epoxide such as a 5-ethyl, 5'-methyl-hydantoin/epichlorogydrin condensation product with a halogenated vinyl polymer such as polyvinylidene fluoride in the presence of a metal halide catalyst. The ether residue of the epoxide is grafted directly to the first carbon-chain carbon of the halogenated vinyl polymer. The graft polymer compositions are utilized as ultrafiltration and reverse osmosis membranes.

Abstract: The subject of this invention is a novel polymeric composition useful in membrane technology such as microfiltration, nanofiltration, ultrafiltration, reverse osmosis and gas separation. The composition is formed by taking a known condensation polymer such as polyether sulfone, polysulfone or a polyarylether sulfone and modifying it to change the molecular weight distribution. The useful polymers of the invention will have an unmodified number average molecular weight of about 63,000 or less and weight fraction of molecules with a molecular weight of 50,000 or less in the range of 30 to 35%. Utilizing fractional precipitation or other known techniques for concentrating a high molecular weight fraction of a polymer the polymers are modified to have a number average molecular weight of a least 59,000 or a weight fraction of molecules with a molecular weight of 50,000 or less of not more than 19%.

Abstract: A cleanable ultrafiltration device and method of making same is the subject of the present invention. The device comprises a housing for receiving a feed stream of a liquid to be filtered and a membrane cartridge disposed in the housing for separating the feed stream into concentrate and permeate. The cartridge is disposed within that housing in spaced relationship to accommodate the flow of the feed stream around the periphery of the cartridge along its length. A plastic netting is typically used for the cartridge/housing spacer. A potted end seal blocks the flow of the by-pass feed stream at the outlet end of the cartridge/housing assembly and forces all of the feed stream through the cartridge. This approach improves operating efficiency by elimination of the wasted by-pass flow associated with the prior art design, while maintaining module cleanability.

Abstract: The subject of the present invention is an improved leaf packet useful in forming a spiral filtration module, the improved module which results from utilization of the leaf packet and a method of preparing the leaf packet. The membrane sheet utilized in forming a spiral filtration module is fused and densified in the area of its fold to increase the sheet density in this area and thus provide protection against mechanical failure. The densification includes the application of heat and pressure to the membrane surface of the sheet so as to densify the membrane surface and seal it against the penetration of feed stream liquid while also densifying the membrane, the backing and an optional reinforcing strip (if utilized).

Abstract: A tubular membrane module system and method which comprise a plurality of UF modules connected in series by U-bends with an end fitting to the modules whose cross sectional flow area is substantially equal to the cross sectional flow area of the U-bends and wherein individual, longitudinal, tapered projections in the end fittings extend in the central flow passageway from the ends of each tube to minimize flow velocity changes of the streams into the central flow channel and into the end of the U-bend by maintaining a substantially constant cross sectional flow area thereby reducing expansion-contraction pressure losses.

Abstract: A filtration system and method constitute the subject matter of the present invention. The system comprises first and second filtration stages which are joined in series with each stage comprising a plurality of filtration modules range for parallel flow. The concentrate from the first stage forms the feed for the second stage and a portion of the second stage concentrate is recirculated to the first stage feed stream. A feed pump and a recirculating pump together with appropriate flow controllers and valves provide means for effecting control over both pressure and flow rate within the system.

Abstract: Method for preparing a fouling-resistant polymer membrane for use in the separation of aqueous, cathodic, electrode-position-paint compositions, which method comprises treating a negative-charged polymer membrane material, having fixed negative-charged groups in the polymer, with a polyelectrolyte polymer having fixed positive-charged nitrogen groups in an amount sufficient to provide for an excess of positive-charged groups in the treated membrane polymer.

Abstract: A spirally wound, high flux membrane module which comprises a feed inlet, a concentration outlet and two permeate outlets and one or more membrane leaves wrapped about a central permeate flow tube to define a permeate flow path in one or more of the membrane leaves and wherein the improvement comprises one or more of the membrane leaves containing two or more separate permeate flow compartments within the membrane leaf to provide for the separate permeate flow of the permeate within the separator compartments to the permeate outlet thereby reducing the area of the permeate back pressure and reducing membrane wrinkling and membrane failure particularly during the membrane cleaning cycles.