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Formation of pore-filled ion-exchange membranes
RESEARCH TRENDS
membranes which define concentrating and diluting flow channels between adjacent membrane pairs. The diluting channels include cation and anion exchange materials, fixed in close contact, to provide conductive paths for ions of the adjacent membranes and flow passages for water between the material. The packing material can include one or more macro-structural elements made of smaller micro-structural elements. The first and second stages can be used to purify water including calcium, carbon dioxide and its hydrates. The ion-exchange material differs in the diluting flow channel of each stage, and the concentrating flow channels can include a brine channel between two guard channels.
Patent number: W O 01/20060 Publication date: 22 March 2001 III
Method for drying hydrogen
Flat adsorption membranes
Applicant." Robert Gordon University, UK
Applicant: Sartorius AG, Germany
A gas dryer is described that includes a membrane located between the inlet and the outlet in the dryer. A wet feed-gas (for example, hydrogen) is passed from the inlet to the outlet over the membrane. Water vapour from the gas passes through the membrane, as it can permeate through the membrane faster than the gas because of the relative permeability of the membrane. A sweep gas may be used to collect the water vapour, and further inlets and outlets may be provided for this purpose. A cellulose acelate membrane is used in the dryer.
The invention relates to a device through which particles can pass, for separating substances by means of the permeation of liquids of more than one layer of porous, flat adsorption membranes. The device is characterized by a high adsorption capacity, even penetration of the target substance and a simple structure. The layers of adsorption membranes are set apart from each other and are provided with at least one hole (preferably a number of holes), to allow the passage of particles. The device can be used to treat liquids containing particles, as are found in, for example, the biotechnology, pharmaceutical, food and chemical industries, or in water and sewage treatment. Patent number: WO 01/19483 Inventors: W. Demmer, D. Nussbaumer Publication date: 22 March 2001
Patent number: W O 01 / 19728 Inventor: E. Gobina Publication date."22 March 2001
IIII
ResearchTrends Formation of pore-filled ion-exchange membranes Robust, polyelectrolyte-filled, micro-porous membranes were prepared by the introduction and cross-linking of a preformed polymer within the pores of a poly(propylene) host membrane. Specifically, poly(vinylbenzyl chloride) (PVBCI) was reacted with piperazine or 1,4 diaminobicyclo[2.2.2]octane in an N,Ndimethylformamide (DMF) solution contained in the pores of the micro-porous basemembrane. The remaining chloromethyl groups were reacted with an amine, such as trimethylamine, to form positively charged ammonium sites. This simple, two-step procedure gave dimensionally stable anionexchange membranes in which the degree of cross-linking and the mass loading were determined by the concentration of PVBC1 and cross-linker in the starting DMF solution. The incorporated polyelectrolyte gel was evenly distributed within the pores of the host membrane with no surface layers present. The membranes are fully characterized. A.K. Pandey, R.E Childs, M. West, J.N.A. Lott, B.E. McCarry, J.M. Dickson: J. of Polymer Science Part A: Polymer Chemistry 39(6) 807-820 (15 March 2001).
Characterization of a Ballard Mk5-E PEM fuel-cell stack Results are presented of an experimental investigation of the energy balance of a Ballard Mark 5-E proton-exchange membrane fuel cell (PEMFC) stack. The authors have investigated the transient phenomena that occur during PEMFC stack warm-up, under load switching, and when the PEMFC stack is connected to a
DC/AC inverter. A simple and convenient model describing the polarization curve as a function of the temperature is presented and validated by the authors' experimental data. They also present experimental results on the increased PEMFC stack performance as a function of the current density for different oxygen concentrations of the oxidant gas. E Laurencelle, R. Chahine, J. Hamelin, K. Agbossou, M. Fournier, T.K. Bose, A. Laperri~re: Fuel Cells 1(1) 66-71 (May 2001).
Polyethylene membranes and hollow fibres Chloro-sulfonated polyethylene membranes and hollow fbres were reacted with allylic amino jojoba to bind the wax chemically to the polymer. The modified membranes and hollow fibres were then tested in the ionexchange and pervaporation processes, respectively. The jojoba-bound polyethylene membranes were selective in preventing transfer of divalent ions such as Ca 2+ and Mg 2÷, while monovalent ions such as K ÷ and Na 2+ could penetrate the membranes. The flux of the monovalent ions depended on the amount of jojoba bound to the polymer, which acted as a barrier to the ions (the monovalent ions could be eluted by acid washing). The concentration of ions (in the range 0.05-1.0M) in the feed solution had little effect on the flux. Preliminary results of pervaporation of a dioxane/water mixture through hollow fibres made of jojoba-bound chloro-sulfonated polyethylene show separation of the dioxane from the water with a separation factor of 6. This technique can be applied to remove residual organic solvents in the purification of industrial waste water. M. Shevachman, S. Belfer, S. Binman, A. Shani: J. of Applied Polymer Science 80(5) 763-768 (2 May 2001).
Permeability and bloodcompatibility properties of membranes To develop blood-compatible membranes with controlled porosity, these researchers have fabricated and examined the properties of a physical inter-penetrating network (PIN) ofchitosan and poly(ethylene oxide)/poly(propylene oxide)/ poly(ethylene oxide) (PEO/PPO/PEO) triblock co-polymers (Pluronics). The degree of equilibrium swelling, scanning electron microscopy, and electron spectroscopy for chemical analysis (ESCA) were used to characterize the bulk and surface properties. Vitamin B12 and human serum albumin were used as permeability markers. Platelet adhesion and activation were used to determine the bloodinteraction properties of the PIN membranes. Unlike chitosan membranes that were nonporous, the chitosan-Pluronic PIN membranes were highly porous with the pore size, depending on the type of incorporated Pluronic polyol. ESCA results showed a significant increase in the - - C - - O - - signal of C1 s spectra on the PIN membranes that correlates with the presence of PEO chains on the surface. The permeability coefficients of vitamin B 12 and albumin were higher in the chitosan-Pluronic PIN membranes than in the control. The number of adherent platelets and the extent of activation were significantly reduced on the chitosan-Pluronic PIN membranes. The decrease in platelet adhesion and activation correlated positively with the PEO chain length of the incorporated Pluronic polyols. The results of this study show that chitosan-Pluronic PIN membranes offer a blood-compatible alternative with a higher-molecular-weight cutoff for use in haemodialysis and related applications. D. Anderson, T. Nguyen, P.-K. Lai, M. Amiji: J.. of Applied Polymer Science 80(8) 1274-1284 (23 May 2001).
MembraneTechnologyNo. 136
membranes which define concentrating and diluting flow channels between adjacent membrane pairs. The diluting channels include cation and anion exchange materials, fixed in close contact, to provide conductive paths for ions of the adjacent membranes and flow passages for water between the material. The packing material can include one or more macro-structural elements made of smaller micro-structural elements. The first and second stages can be used to purify water including calcium, carbon dioxide and its hydrates. The ion-exchange material differs in the diluting flow channel of each stage, and the concentrating flow channels can include a brine channel between two guard channels.
Patent number: W O 01/20060 Publication date: 22 March 2001 III
Method for drying hydrogen
Flat adsorption membranes
Applicant." Robert Gordon University, UK
Applicant: Sartorius AG, Germany
A gas dryer is described that includes a membrane located between the inlet and the outlet in the dryer. A wet feed-gas (for example, hydrogen) is passed from the inlet to the outlet over the membrane. Water vapour from the gas passes through the membrane, as it can permeate through the membrane faster than the gas because of the relative permeability of the membrane. A sweep gas may be used to collect the water vapour, and further inlets and outlets may be provided for this purpose. A cellulose acelate membrane is used in the dryer.
The invention relates to a device through which particles can pass, for separating substances by means of the permeation of liquids of more than one layer of porous, flat adsorption membranes. The device is characterized by a high adsorption capacity, even penetration of the target substance and a simple structure. The layers of adsorption membranes are set apart from each other and are provided with at least one hole (preferably a number of holes), to allow the passage of particles. The device can be used to treat liquids containing particles, as are found in, for example, the biotechnology, pharmaceutical, food and chemical industries, or in water and sewage treatment. Patent number: WO 01/19483 Inventors: W. Demmer, D. Nussbaumer Publication date: 22 March 2001
Patent number: W O 01 / 19728 Inventor: E. Gobina Publication date."22 March 2001
IIII
ResearchTrends Formation of pore-filled ion-exchange membranes Robust, polyelectrolyte-filled, micro-porous membranes were prepared by the introduction and cross-linking of a preformed polymer within the pores of a poly(propylene) host membrane. Specifically, poly(vinylbenzyl chloride) (PVBCI) was reacted with piperazine or 1,4 diaminobicyclo[2.2.2]octane in an N,Ndimethylformamide (DMF) solution contained in the pores of the micro-porous basemembrane. The remaining chloromethyl groups were reacted with an amine, such as trimethylamine, to form positively charged ammonium sites. This simple, two-step procedure gave dimensionally stable anionexchange membranes in which the degree of cross-linking and the mass loading were determined by the concentration of PVBC1 and cross-linker in the starting DMF solution. The incorporated polyelectrolyte gel was evenly distributed within the pores of the host membrane with no surface layers present. The membranes are fully characterized. A.K. Pandey, R.E Childs, M. West, J.N.A. Lott, B.E. McCarry, J.M. Dickson: J. of Polymer Science Part A: Polymer Chemistry 39(6) 807-820 (15 March 2001).
Characterization of a Ballard Mk5-E PEM fuel-cell stack Results are presented of an experimental investigation of the energy balance of a Ballard Mark 5-E proton-exchange membrane fuel cell (PEMFC) stack. The authors have investigated the transient phenomena that occur during PEMFC stack warm-up, under load switching, and when the PEMFC stack is connected to a
DC/AC inverter. A simple and convenient model describing the polarization curve as a function of the temperature is presented and validated by the authors' experimental data. They also present experimental results on the increased PEMFC stack performance as a function of the current density for different oxygen concentrations of the oxidant gas. E Laurencelle, R. Chahine, J. Hamelin, K. Agbossou, M. Fournier, T.K. Bose, A. Laperri~re: Fuel Cells 1(1) 66-71 (May 2001).
Polyethylene membranes and hollow fibres Chloro-sulfonated polyethylene membranes and hollow fbres were reacted with allylic amino jojoba to bind the wax chemically to the polymer. The modified membranes and hollow fibres were then tested in the ionexchange and pervaporation processes, respectively. The jojoba-bound polyethylene membranes were selective in preventing transfer of divalent ions such as Ca 2+ and Mg 2÷, while monovalent ions such as K ÷ and Na 2+ could penetrate the membranes. The flux of the monovalent ions depended on the amount of jojoba bound to the polymer, which acted as a barrier to the ions (the monovalent ions could be eluted by acid washing). The concentration of ions (in the range 0.05-1.0M) in the feed solution had little effect on the flux. Preliminary results of pervaporation of a dioxane/water mixture through hollow fibres made of jojoba-bound chloro-sulfonated polyethylene show separation of the dioxane from the water with a separation factor of 6. This technique can be applied to remove residual organic solvents in the purification of industrial waste water. M. Shevachman, S. Belfer, S. Binman, A. Shani: J. of Applied Polymer Science 80(5) 763-768 (2 May 2001).
Permeability and bloodcompatibility properties of membranes To develop blood-compatible membranes with controlled porosity, these researchers have fabricated and examined the properties of a physical inter-penetrating network (PIN) ofchitosan and poly(ethylene oxide)/poly(propylene oxide)/ poly(ethylene oxide) (PEO/PPO/PEO) triblock co-polymers (Pluronics). The degree of equilibrium swelling, scanning electron microscopy, and electron spectroscopy for chemical analysis (ESCA) were used to characterize the bulk and surface properties. Vitamin B12 and human serum albumin were used as permeability markers. Platelet adhesion and activation were used to determine the bloodinteraction properties of the PIN membranes. Unlike chitosan membranes that were nonporous, the chitosan-Pluronic PIN membranes were highly porous with the pore size, depending on the type of incorporated Pluronic polyol. ESCA results showed a significant increase in the - - C - - O - - signal of C1 s spectra on the PIN membranes that correlates with the presence of PEO chains on the surface. The permeability coefficients of vitamin B 12 and albumin were higher in the chitosan-Pluronic PIN membranes than in the control. The number of adherent platelets and the extent of activation were significantly reduced on the chitosan-Pluronic PIN membranes. The decrease in platelet adhesion and activation correlated positively with the PEO chain length of the incorporated Pluronic polyols. The results of this study show that chitosan-Pluronic PIN membranes offer a blood-compatible alternative with a higher-molecular-weight cutoff for use in haemodialysis and related applications. D. Anderson, T. Nguyen, P.-K. Lai, M. Amiji: J.. of Applied Polymer Science 80(8) 1274-1284 (23 May 2001).
MembraneTechnologyNo. 136