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Cleaning UF inorganic membranes
Nov memb.qxd
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RESEARCH TRENDS ...Continued from p 12 including at least one type of polyimide. Using this, it is possible to produce a gas separation membrane with low permeation resistance (a high permeation rate) for permeate gases that pass through the porous layer of the membrane. The membrane structure also maintains a practical level of mechanical strength, and it is resistant to both hot and cold water. Patent number: US 6464755 Inventors: S. Nakanishi, T. Yoshinaga, K. Ito, Y. Kusuki Publication date: 15 October 2002
Apparatus for continuously monitoring membrane fouling Assignee: Korea Institute of Science and Technology, Korea The patent provides details of a method of membrane filtration and an apparatus for continuously monitoring the state of a membrane during the filtration (particularly for membrane fouling caused by cake or gel layers of solutes that develop on the surfaces of a filtered membrane). The monitoring process is achieved by estimating the membrane potential and membrane solute rejection, while measuring a set of physical properties. These include feed; variations of a streaming potential difference across the pores of the membrane; variation in pressure differences between an upstream side and a downstream side of the membrane; and concentration differences between the feed and permeate filtered through the membrane.
Research Trends Separation of IgG from human plasma using hollow-fibre membranes To replace conventional bioaffinity ligand-like protein A or protein G, pseudo-bioaffinity ligands seem to be an interesting alternative for the purification of immunoglobulin G (IgG). In this study, thiophilic ligand (T-gel) was immobilized on a hollow-fibre membrane, based on a copolymer of ethylene and vinyl alcohol (PEVA), to obtain an affinity support for the purification of IgG from human plasma. Microporous hollow fibres have been modified via divinyl sulphone activation and coupled by 2-mercaptoethanol (T-PEVA). The affinity module allowed the purification of IgG from human plasma with high efficiency (85% of IgG loaded were adsorbed) with a very small contamination of albumin (less than 1%). The enrichment was quite high (IgG/albumin) as shown by a final ratio of 39.3/0.27 before loading. The binding capacity could allow the separation of 1.5 g of IgG from human plasma with a functionalized membrane surface area of 1 m2. The authors tried to minimize sample preparation by
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Patent number: US 6463790 Inventors: M.-S. Chun, J.J. Kim, S.-Y. Lee Publication date: 15 October 2002
Method of generating uniform pores in thin polymer films Applicant: Aradigm Corp, USA A method of generating pores in thin sheets of a material – typically thin polymer films, is provided. The method allows for the generation of pores which uniformly penetrate the material. The method comprises laminating a thick film onto a thin film, and then directing a laser source onto the thin film so as to form pores in it. The increased stiffness conferred by the thick film (20) reduces wrinkle formation in the thin film, and results in uniform thickness of the thin film, and uniformity of pore depth. The invention also provides details of devices that comprise membranes, and which are formed according to the patent. Patent number: WO 02/081097 Inventor: S. Srinivasan Publication date: 17 October 2002
Hollow fibre membrane module Applicant: Kuraray Co Ltd, Japan This patent describes a hollow fibre membrane module. It has a horizontal cross-sectional shape (polygonal with three or more sides) that is suitable for storing a number of columnar hollow fibre membrane elements. A dead space on the outside of the hollow fibre membrane elements is less than that of a conventional module with a decreasing the salt concentration, the sample dilution and by optimizing the rinsing and elution steps. This thiophilic derivatized hollow-fibre module proved that it could be used as a very efficient tool for the purification of IgG provided that a high concentration of salt was added. Y. Coffinier, C. Legallais, M.A. Vijayalakshmi: J. of Membrane Science 208 (1–2) 13–22 (1 October 2002).
Cleaning UF inorganic membranes The rinsing and alkaline cleaning of an ultrafiltration (UF) inorganic membrane fouled with whey proteins was investigated. The progression of both processes was assessed by membrane hydraulic resistance restoration and fouling deposit removal. The amount of protein removed during rinsing is quite significant, compared with the total amount removed during rinsing and cleaning. Increased ionic strength of the rinsing solution (by adding NaCl) resulted in an impressive increase of calcium removal during the rinsing step. This is probably attributed to calcium/sodium ion exchange. The effect of increased calcium removal on rinsing and cleaning efficiency was not significant. The kinetics of rinsing and cleaning were also considered. P. Matzinos, R. Álvarez: J. of Membrane Science 208(1–2) 23–30 (1 October 2002).
circular cross-section. This means that the size of a device can be reduced, and because the amount of liquid concentrate filling the hollow fibre membrane module can be reduced by an amount that is equal to the reduced dead space, the recovery rate can be increased and the amount of chemicals used can be reduced. Patent number: WO 02/081066 Inventors: K. Inoue, S. Nakahara, T. Miyake, H. Horiuchi, M. Kobayashi, K. Komatsu Publication date: 17 October 2002
Potting method Applicant: US Filter Wastewater Group Inc, USA, and Seitzschenk Filtersystems GmbH, Germany A method of forming a pot for an array of hollow fibre membranes, including the steps of placing the ends of the fibre membranes into a mould, is detailed. A first layer of curable resin material (in a non-cured state) is formed around the fibre membrane ends. A second layer of an additional (or second) material is applied to the first layer before the latter is fully cured. The second material layer is chemically reactive with the first layer and forms an adhesive bond between the two layers. Both layers are at least partially cured before the pot, formed from the mould, is removed. When each layer is fully cured, the second one is more flexible than the first. An apparatus for carrying out the potting method is also disclosed. Patent number: WO 02/081065 Inventors: D.J. Cox, G. Schnieder, F. Zha, J. Muller, C. Lea Publication date: 17 October 2002
Permeation model for erythromycin The permeation of erythromycin, macrolide antibiotics, into a water/oil emulsion globule was simulated with a multi-layer liquid membrane model. The formation of an unfavourable concentration profile in an emulsion globule would cause low separation performance. Therefore, it was proposed that to control the formation of the concentration profile, the feed phase and emulsion should be contacted as dispersed and continuous phases respectively, in a spray column contactor. A series of permeation experiments was conducted (both batch and continuous operations) with a spray column. In the cases of batch permeation runs, erythromycin permeated through the membrane phase and was concentrated in the stripping phase. By the new contacting method, an improvement in the separation performance was achieved. Also the stability of the emulsion membrane improved – specifically mechanical entrainment. Finally, a theoretical evaluation of the permeation, with respect to the dispersion in the column, is discussed. H. Habaki, R. Egashira, G.W. Stevens, J. Kawasaki: J. of Membrane Science 208(1–2) 89–103 (1 October 2002).
Properties of a modified HTPB-based polyurethane membrane A hydroxyl-terminated polybutadiene (HTPB) based polyurethane (PU) solution was
Membrane Technology November 2002
19/11/2002
15:24
Page 14
RESEARCH TRENDS ...Continued from p 12 including at least one type of polyimide. Using this, it is possible to produce a gas separation membrane with low permeation resistance (a high permeation rate) for permeate gases that pass through the porous layer of the membrane. The membrane structure also maintains a practical level of mechanical strength, and it is resistant to both hot and cold water. Patent number: US 6464755 Inventors: S. Nakanishi, T. Yoshinaga, K. Ito, Y. Kusuki Publication date: 15 October 2002
Apparatus for continuously monitoring membrane fouling Assignee: Korea Institute of Science and Technology, Korea The patent provides details of a method of membrane filtration and an apparatus for continuously monitoring the state of a membrane during the filtration (particularly for membrane fouling caused by cake or gel layers of solutes that develop on the surfaces of a filtered membrane). The monitoring process is achieved by estimating the membrane potential and membrane solute rejection, while measuring a set of physical properties. These include feed; variations of a streaming potential difference across the pores of the membrane; variation in pressure differences between an upstream side and a downstream side of the membrane; and concentration differences between the feed and permeate filtered through the membrane.
Research Trends Separation of IgG from human plasma using hollow-fibre membranes To replace conventional bioaffinity ligand-like protein A or protein G, pseudo-bioaffinity ligands seem to be an interesting alternative for the purification of immunoglobulin G (IgG). In this study, thiophilic ligand (T-gel) was immobilized on a hollow-fibre membrane, based on a copolymer of ethylene and vinyl alcohol (PEVA), to obtain an affinity support for the purification of IgG from human plasma. Microporous hollow fibres have been modified via divinyl sulphone activation and coupled by 2-mercaptoethanol (T-PEVA). The affinity module allowed the purification of IgG from human plasma with high efficiency (85% of IgG loaded were adsorbed) with a very small contamination of albumin (less than 1%). The enrichment was quite high (IgG/albumin) as shown by a final ratio of 39.3/0.27 before loading. The binding capacity could allow the separation of 1.5 g of IgG from human plasma with a functionalized membrane surface area of 1 m2. The authors tried to minimize sample preparation by
14
Patent number: US 6463790 Inventors: M.-S. Chun, J.J. Kim, S.-Y. Lee Publication date: 15 October 2002
Method of generating uniform pores in thin polymer films Applicant: Aradigm Corp, USA A method of generating pores in thin sheets of a material – typically thin polymer films, is provided. The method allows for the generation of pores which uniformly penetrate the material. The method comprises laminating a thick film onto a thin film, and then directing a laser source onto the thin film so as to form pores in it. The increased stiffness conferred by the thick film (20) reduces wrinkle formation in the thin film, and results in uniform thickness of the thin film, and uniformity of pore depth. The invention also provides details of devices that comprise membranes, and which are formed according to the patent. Patent number: WO 02/081097 Inventor: S. Srinivasan Publication date: 17 October 2002
Hollow fibre membrane module Applicant: Kuraray Co Ltd, Japan This patent describes a hollow fibre membrane module. It has a horizontal cross-sectional shape (polygonal with three or more sides) that is suitable for storing a number of columnar hollow fibre membrane elements. A dead space on the outside of the hollow fibre membrane elements is less than that of a conventional module with a decreasing the salt concentration, the sample dilution and by optimizing the rinsing and elution steps. This thiophilic derivatized hollow-fibre module proved that it could be used as a very efficient tool for the purification of IgG provided that a high concentration of salt was added. Y. Coffinier, C. Legallais, M.A. Vijayalakshmi: J. of Membrane Science 208 (1–2) 13–22 (1 October 2002).
Cleaning UF inorganic membranes The rinsing and alkaline cleaning of an ultrafiltration (UF) inorganic membrane fouled with whey proteins was investigated. The progression of both processes was assessed by membrane hydraulic resistance restoration and fouling deposit removal. The amount of protein removed during rinsing is quite significant, compared with the total amount removed during rinsing and cleaning. Increased ionic strength of the rinsing solution (by adding NaCl) resulted in an impressive increase of calcium removal during the rinsing step. This is probably attributed to calcium/sodium ion exchange. The effect of increased calcium removal on rinsing and cleaning efficiency was not significant. The kinetics of rinsing and cleaning were also considered. P. Matzinos, R. Álvarez: J. of Membrane Science 208(1–2) 23–30 (1 October 2002).
circular cross-section. This means that the size of a device can be reduced, and because the amount of liquid concentrate filling the hollow fibre membrane module can be reduced by an amount that is equal to the reduced dead space, the recovery rate can be increased and the amount of chemicals used can be reduced. Patent number: WO 02/081066 Inventors: K. Inoue, S. Nakahara, T. Miyake, H. Horiuchi, M. Kobayashi, K. Komatsu Publication date: 17 October 2002
Potting method Applicant: US Filter Wastewater Group Inc, USA, and Seitzschenk Filtersystems GmbH, Germany A method of forming a pot for an array of hollow fibre membranes, including the steps of placing the ends of the fibre membranes into a mould, is detailed. A first layer of curable resin material (in a non-cured state) is formed around the fibre membrane ends. A second layer of an additional (or second) material is applied to the first layer before the latter is fully cured. The second material layer is chemically reactive with the first layer and forms an adhesive bond between the two layers. Both layers are at least partially cured before the pot, formed from the mould, is removed. When each layer is fully cured, the second one is more flexible than the first. An apparatus for carrying out the potting method is also disclosed. Patent number: WO 02/081065 Inventors: D.J. Cox, G. Schnieder, F. Zha, J. Muller, C. Lea Publication date: 17 October 2002
Permeation model for erythromycin The permeation of erythromycin, macrolide antibiotics, into a water/oil emulsion globule was simulated with a multi-layer liquid membrane model. The formation of an unfavourable concentration profile in an emulsion globule would cause low separation performance. Therefore, it was proposed that to control the formation of the concentration profile, the feed phase and emulsion should be contacted as dispersed and continuous phases respectively, in a spray column contactor. A series of permeation experiments was conducted (both batch and continuous operations) with a spray column. In the cases of batch permeation runs, erythromycin permeated through the membrane phase and was concentrated in the stripping phase. By the new contacting method, an improvement in the separation performance was achieved. Also the stability of the emulsion membrane improved – specifically mechanical entrainment. Finally, a theoretical evaluation of the permeation, with respect to the dispersion in the column, is discussed. H. Habaki, R. Egashira, G.W. Stevens, J. Kawasaki: J. of Membrane Science 208(1–2) 89–103 (1 October 2002).
Properties of a modified HTPB-based polyurethane membrane A hydroxyl-terminated polybutadiene (HTPB) based polyurethane (PU) solution was
Membrane Technology November 2002