- Email: [email protected]
NF
substances, and an improved production method. The module comprises a bundled configuration of hollow thread-type porous polymer membrane elements. The bundle is sealed in a casing, in which the membrane elements are bound to each other by molten thermoplastic resin. The membrane elements are arranged in a planar configuration to form the module, and the ends of the planar membrane elements are placed between elongated thermoplastic resin films to form a sheet. The sheet is heated to weld the films together and/or to the membrane elements; an’d then rolled up in a longitudinal direction so that the membrane elements are spirally wound, with each layer being planar and including the parallel porous membrane elements. Finally) the rolled-up configuration is inserted into the casing, and the thermoplastic resin films are melted to bind the ends of the membrane elements to each other and the casing’s inner wall. Patent number: US 5885454 Inventors: T. Yagihashi, T. A&, K. Tukamoto Pubhtion date: 23 March 1999
including a porous solid phase which comprises the membrane. Patent number: US 5885456 Inventors: J. Charkoudian, A.E. Allegrezza Jr Pubublicationdate: 23 March 1999
Highly asymmetric PES membranes Applicant: Memtec America Corporation, Australia Highly asymmetric polyethersulfone (PES) membranes prepared from a stable, clear, homogeneous solution or stable colloidal dispersion of polyethersulfone are describeal. The membranes have a porous skin with a high density of skin pores, with an average diameter between about 0.001 and 20 pm. In addition, the membrane has a porous support with an asymmetric region of gradually increasing pore diameters, so that the opposite face of the membrane has an average pore diameter between about 50 and 10,000 times the diameter of the skin pores. Patent rwzber: US 5886059 Inventor: I.-F. Wang Publication ddte: 23 March 1999
Poiysulfone copolymer membranes Applicant: M&pore Corporation, USA in this patent a porous membrane, such as a microporous or ultrafiltration membrane, is formed from a solution of a polysulfone and a free radical poiymerisable monomer exposed to UV light. This forms a blend of the polysulfone and copolymers of polysulfone activation products and polymerised monomer with polymer segments covalently bonded to each other. The solution is separated into two phases,
Research Trends Removal of nitrate from groundwater using The intensive development of agriculture and application of chemicals has led to the contamination with nitrates of many natural water reservoirs and groundwaters. This paper reviews an attempt at removal of nitrate ions from tap water by means of the combined and processes of reverse osmosis (RO) nanofiltration (NF). In the first stage, the water was filtered using nanofiltration membranes, which resulted in the absence of bivalent ions in the permeate obtained. Then the filtrate was concentrated using reverse osmosis. Because the substances that form membranse scale (CaSO,, CaC03) were removed from lthe filtrate, the
@I
-
Microporous membrane Applicant: Dow Chemical Company, USA The patent describes a pr-ocess for the prepararion of a microporous membrane from sulfide) poly(phenylene an unsulfonated polymer by forming a mixture of unsulfonated poly(phenylene sulfide) ard amorphous polymers, and optionally a plasticiser. The resulting mixture is then heated, extruded or optionally cast into a membrane, which is
efficiency of this process was iimited mainly by the osmotic pressure of the retentate. J. Bohdziewicz, M. Bodzek, E. Wasik: Desalination 121(2) 139-147 (12 March 1999).
Ultra-low-pressure water softening The ultra-low-pressure water-softening properties of a series of novel membranes containing cross-linked poly(4-vinylpyridinium:l salts incorporated into the pores of polyethylene or polypropylene microfiltration membranes have been examined. It has b#een shown that these membranes exhibit excellent separation properties with high permea.bilities at low transmembrane pressures. The separation mechanism in these pore-filled membranes is primarily due to Donnan exclusion, and as such. bivalent cations are more strongly rejected than monovalent ions. Moreover, it has been shown that relatively large molecules such as sucrose are only rejected to a limited extent. The membranes have been shown to withstand free chlorine at ambient temperatures. The performance of the pore-filled membranes has,
cooled (quenched), coagulated and leached. The membrane can be drawn before, during and/or after leaching. Patent number: US 5888434 Inventors: R.D. Mahoney, J. Kawamoto, R.A. Lundgard, M.F. Sonnenschein, H.S. Wan, H.N. Beck Publication date: 30 March I 999
Polysulfone semipermeable membrane Applicant: Nitto Denko Corporation, Japan The semipermeable membrane of polysulfone resin described in this patent is formed from a continuous structure of a homogeneous skin layer with an average thickness of 5-1000 nm, and a porous layer of the same material as ~ although thicker than - the skin layer. The porous layer has voids with an average pore diameter of less than 3 pm, which means that it can act as a cost-effective gas separation membrane with high permeation flux. In its preparation, diethylene glycol dimethyl ether was added to polysulfone for dissolution, and the resultant solution was defoamed. The solution was cast onto a support layer of polyester nonwoven fabric using an applicator, dipped in water as a solidifying liquid, and dried. The resulting semipermeable membrane comprises a homogeneous skin layer and a porous layer. A crosslinking silicone resin solution may be applied to the surface of the membrane to form a protective film. Patent number: US 5888605 Irzventorst H. Hachisuka, K. Ikeda Publication date: 30 March 1999
been shown to compare favourably with existing state-of-the-art thin-film composite (TFC) nanofiltration membranes (Osmonics Desal-51 and BQOl and Hydranautics TFV-7450). In contrast to the TFC membranes, the separating layer in these pore-filled membranes has been shown to be thick, ranging from 80 to 160 pm. These polyelectrolyte pore-filled membranes offer a new paradigm in the construction of high-performance water-softening membranes. A.M. Mika, R.F. Childs, J.M. Dickson: Desalination 121(2)149-158 (12 March 1999).
Porous latex composite membranes new class of microfiltration (MF) and ultrafiltration (UF) membranes has been developed. By placing latex particles onto the surface of a microporous substrate and stab&sing the porous array, voids are formed between the particles which provide narrowly distributed pores that serve as separation channels. The size of the interstitial voids in the array is governed by the diameter of the latex particle. This aqueous-based technology has
A
Membrane Technology No. 109
including a porous solid phase which comprises the membrane. Patent number: US 5885456 Inventors: J. Charkoudian, A.E. Allegrezza Jr Pubublicationdate: 23 March 1999
Highly asymmetric PES membranes Applicant: Memtec America Corporation, Australia Highly asymmetric polyethersulfone (PES) membranes prepared from a stable, clear, homogeneous solution or stable colloidal dispersion of polyethersulfone are describeal. The membranes have a porous skin with a high density of skin pores, with an average diameter between about 0.001 and 20 pm. In addition, the membrane has a porous support with an asymmetric region of gradually increasing pore diameters, so that the opposite face of the membrane has an average pore diameter between about 50 and 10,000 times the diameter of the skin pores. Patent rwzber: US 5886059 Inventor: I.-F. Wang Publication ddte: 23 March 1999
Poiysulfone copolymer membranes Applicant: M&pore Corporation, USA in this patent a porous membrane, such as a microporous or ultrafiltration membrane, is formed from a solution of a polysulfone and a free radical poiymerisable monomer exposed to UV light. This forms a blend of the polysulfone and copolymers of polysulfone activation products and polymerised monomer with polymer segments covalently bonded to each other. The solution is separated into two phases,
Research Trends Removal of nitrate from groundwater using The intensive development of agriculture and application of chemicals has led to the contamination with nitrates of many natural water reservoirs and groundwaters. This paper reviews an attempt at removal of nitrate ions from tap water by means of the combined and processes of reverse osmosis (RO) nanofiltration (NF). In the first stage, the water was filtered using nanofiltration membranes, which resulted in the absence of bivalent ions in the permeate obtained. Then the filtrate was concentrated using reverse osmosis. Because the substances that form membranse scale (CaSO,, CaC03) were removed from lthe filtrate, the
@I
-
Microporous membrane Applicant: Dow Chemical Company, USA The patent describes a pr-ocess for the prepararion of a microporous membrane from sulfide) poly(phenylene an unsulfonated polymer by forming a mixture of unsulfonated poly(phenylene sulfide) ard amorphous polymers, and optionally a plasticiser. The resulting mixture is then heated, extruded or optionally cast into a membrane, which is
efficiency of this process was iimited mainly by the osmotic pressure of the retentate. J. Bohdziewicz, M. Bodzek, E. Wasik: Desalination 121(2) 139-147 (12 March 1999).
Ultra-low-pressure water softening The ultra-low-pressure water-softening properties of a series of novel membranes containing cross-linked poly(4-vinylpyridinium:l salts incorporated into the pores of polyethylene or polypropylene microfiltration membranes have been examined. It has b#een shown that these membranes exhibit excellent separation properties with high permea.bilities at low transmembrane pressures. The separation mechanism in these pore-filled membranes is primarily due to Donnan exclusion, and as such. bivalent cations are more strongly rejected than monovalent ions. Moreover, it has been shown that relatively large molecules such as sucrose are only rejected to a limited extent. The membranes have been shown to withstand free chlorine at ambient temperatures. The performance of the pore-filled membranes has,
cooled (quenched), coagulated and leached. The membrane can be drawn before, during and/or after leaching. Patent number: US 5888434 Inventors: R.D. Mahoney, J. Kawamoto, R.A. Lundgard, M.F. Sonnenschein, H.S. Wan, H.N. Beck Publication date: 30 March I 999
Polysulfone semipermeable membrane Applicant: Nitto Denko Corporation, Japan The semipermeable membrane of polysulfone resin described in this patent is formed from a continuous structure of a homogeneous skin layer with an average thickness of 5-1000 nm, and a porous layer of the same material as ~ although thicker than - the skin layer. The porous layer has voids with an average pore diameter of less than 3 pm, which means that it can act as a cost-effective gas separation membrane with high permeation flux. In its preparation, diethylene glycol dimethyl ether was added to polysulfone for dissolution, and the resultant solution was defoamed. The solution was cast onto a support layer of polyester nonwoven fabric using an applicator, dipped in water as a solidifying liquid, and dried. The resulting semipermeable membrane comprises a homogeneous skin layer and a porous layer. A crosslinking silicone resin solution may be applied to the surface of the membrane to form a protective film. Patent number: US 5888605 Irzventorst H. Hachisuka, K. Ikeda Publication date: 30 March 1999
been shown to compare favourably with existing state-of-the-art thin-film composite (TFC) nanofiltration membranes (Osmonics Desal-51 and BQOl and Hydranautics TFV-7450). In contrast to the TFC membranes, the separating layer in these pore-filled membranes has been shown to be thick, ranging from 80 to 160 pm. These polyelectrolyte pore-filled membranes offer a new paradigm in the construction of high-performance water-softening membranes. A.M. Mika, R.F. Childs, J.M. Dickson: Desalination 121(2)149-158 (12 March 1999).
Porous latex composite membranes new class of microfiltration (MF) and ultrafiltration (UF) membranes has been developed. By placing latex particles onto the surface of a microporous substrate and stab&sing the porous array, voids are formed between the particles which provide narrowly distributed pores that serve as separation channels. The size of the interstitial voids in the array is governed by the diameter of the latex particle. This aqueous-based technology has
A
Membrane Technology No. 109