Polyvinyl alcohol membrane

As a base of proton conducting membrane polyvinyl alcohol (PVS) and phenolsulfonic acid (PSA) was synthesized [9]. Membrane is rendered on a surface of a catalytic layer and dries up at room temperature. As shown in [9], at ratio PVS PSA=4 1 the membrane surpasses widely used in PEMFC membranes on the Nafion basis. Besides, experimental data testily that the solution can successfully be used as a connecting element for the anode and the cathode bonding at FC assembly. 

Polymeric Membranes Economically important applications required membranes that could operate at higher pH than could CA, for which the optimum is around pH = 5. Many polymeric membranes are now available, most of which have excellent hydrolytic stabihty. Particularly prominent are polysulfone, polyvinyhdene fluoride, poly-ethersulfone, polyvinyl alcohol-polyethylene copolymers, and aciylic copolymers. 

Pervaporation Membranes Pervaporation has a long history, and many materials have found use in pervaporation experiments. Cellulosic-based materials have given way to polyvinyl alcohol and blends of polyvinyl alcohol and acrylics in commercial water-removing membranes. These membranes are typically solution cast (from... 

J. Xu et al. [283] have shown that immobilization of enzymes can be done using a specially designed composite membrane with a porous hydrophobic layer and a hydrophilic ultrafiltration layer. A polytetrafluoroethylene (PTFE) membrane with micrometer pores as an excellent hydrophobic support for immobilization was employed for the porous hydrophobic layer, and a biocompatible material of polyvinyl alcohol (PVA) which provided a favourable environment to retain the lipase activity was used to prepare the hydrophilic... 

At present, there is one main commercial application of pervaporation, the production of high purity alcohol by a hybrid process which also incorporates distillation. Such separations use cellulose-acetate-based composite-membranes, with an active layer of polyvinyl alcohol, for example. Membrane fluxes are in the range 0.45-2.2 kg/m2 h. Pervaporation... 

Glassy polymers with much higher glass transition temperatures and more rigid polymer chains than rubbery polymers have been extensively used as the continuous polymer matrices in the zeolite/polymer mixed-matrix membranes. Typical glassy polymers in the mixed-matrix membranes include cellulose acetate, polysul-fone, polyethersulfone, polyimides, polyetherimides, polyvinyl alcohol, Nafion , poly(4-methyl-2-pentyne), etc. 

Preparation conditions of asymmetric polyvinyl alcohol membranes ... 

The membranes were cast from a 9% aqueous solution of 100% hydrolyzed, 115,000 MW polyvinyl alcohol. 

The results of a reverse osmosis study of radiation crossllnk-ed and heat treated polyvinyl alcohol(PVA) membranes are reported. In the framework of this study the permeability of water and salt through these membranes was investigated. In parallel, the diffusive transport of salt through PVA was also studied. The results suggest that the transport of salt and water through PVA is uncoupled, The salt transport data can be rationalized in terms of a modified solution-diffusion model. 

Polymers may exhibit non-Fickian diffusion below the Tgt but a transition to Fickian diffusion is noted as the temperature is raised above the Tr The permeability of a gas, such as oxygen, is much greater through a silicone membrane than through a polyvinyl alcohol (PVA) membrane. Permeability of specific gases may be controlled by the use of composite membranes. 

A great many different materials have been used in osmotic pressure experiments. Various forms of cellophane and animal membranes are probably the most common membrane materials. Various other polymers, including polyvinyl alcohol, polyurethane, and polytrifluorochl-oroethylene, have also been used along with such inorganic substances as CuFe(CN)6 precipitated in a porous support. 

Recently a metal ion-imprinted membrane was developed for selective separation of silver ions [215]. Chitosan and polyvinyl alcohol were blended in the presence of... 

Mitsubayashi et al. [89] Trimethylamine Mackerel Flavin-containing monooxygenase type-3 (FM03)/in polyvinyl alcohol membrane containing stilbazolium groups. Covered with a Nylon membrane Oxygen electrode ... 

A list of typical commercial pervaporation membranes [23] is given in Table 3.1. Commercial hydrophilic membranes are very often made of polyvinyl alcohol (PVA), with differences in the degree of crosslinking. Commercial hydrophobic membranes often have a top layer in polydimethyl siloxane (PDMS). However, a wide variety of membrane materials for pervaporation can be found in the literature, including polymethylglutamate, polyacrylonitrile, polytetrafluoroethylene, polyvinylpyrrolidone, styrene-butadiene rubber, polyacrylic acid, and many others [24]. A comprehensive overview of membrane materials for pervaporation is given by Semenova et al. [25],... 

Textile sizing agents such as polyvinyl alcohol may also be reclaimed from hot process water. Here, both polymeric membranes and inorganic, dynamic membranes are appropriate choices. Systems based on polymeric membranes operate at lower fluxes and require less recirculation pumping, and are somewhat more economical. Plants with treatment capacities as high as 60 m3 per hour are in operation. 

Acetylcholineesterase and choline oxidase Enzyme membrane in H20 was treated with 11% solution of PVA-SbQ (polyvinyl alcohol) with styryl pyridinium groups. Mixture was spread on a cellulose nitrate membrane and air dried. The membrane was exposed to UV radiation for 3 h and stored at 4°C. The enzyme membrane was fixed with a Pt electrode. Sample was dissolved in phosphate buffer and measured. The best results were obtained at pH 8 and at 30°. The calibration graph was rectilinear for 5mM ACh. The storage stability of the dry membrane was excellent. [77]... 

Electrophoresis protein separation membranes have been prepared by step-growth condensation of water-soluble polyvinyl alcohol with selected water-soluble difunctional crosslinking agents. These membranes have broad pore size ranges, restricted pore size distribution, greater resistance to hydrolysis in an alkaline medium, and improved gel clarity when higher amounts of crosslinkers are used. 

Preparation of Polyvinyl Alcohol Membrane Crosslinked with Glutaraldehyde... 

A reaction vessel was charged with 10 ml 5% of solution polyvinyl alcohol having a M of roughly 20,000 daltons of which 97.5% to 99.5 % were hydrolyzed and 0.333 pL of 6.0M hydrochloric acid and then treated with 91.5 pL of 25% solution of glutaraldehyde. The solution was then poured across a PET support and allowed to stand at ambient temperature for 30 minutes. The membranes were washed with excess distilled water to remove residual catalyst prior to use. 

TABLE 1. Membranes prepared by reacting selected crosslinking agents with 10 ml of 5% solution of polyvinyl alcohol having a M of ronghly 20,000 daltons and 97.5% to 99.5 % hydrolyzed. 

TABLE 2. Experimental electrophoresis protein separation conditions using membranes prepared by reacting polyvinyl alcohol having a M of roughly 20,000 daltons 97.5% to 99.5% hydrolyzed and selected crosslinking agents. 

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