Cellulose Triacetate Membrane Research Articles

Carrier-mediated transport of rare earth ions through cellulose triacetate membranes

Fluxes of trivalent rare earth ions (Sc 3+, Y 3+, La 3+, Pr 3+, Sm 3+, Tb 3+, Er 3+ and Lu 3+) across cellulose triacetate membranes containing a plasticizer were determined using benzoylacetone, dibenzoylmethane and benzoyl-, thenoyl- and furoyltrifluoracetone as carriers. The transport of rare earths was coupled to a flow of hydrogen ions. Effect of pH on the flux of rare earths was examined by changing the pH of the feed solution. The transport of scandium occurred at lower pH than that of yttrium and lanthanum. Transport of rare earths using the trifluoroacetone derivatives was observed at lower pH than when benzoylacetone or dibenzoylmethane were used. At pH 5.1 and 6.1, benzoyl- and thenoyltrifluoroacetone exhibited an appreciable flux of rare earths; however, no significant difference in flux among the rare earths was recognized, with the exception of scandium. At pH 7.3 and 8.2, relatively low fluxes were observed for the membranes containing benzoylacetone and dibenzoylmethane, and no transport of some lanthanides occurred. In the competitive transport of scandium and lanthanum, the flux ratio of scandium to lanthanum was higher than that obtained by single rare earth transport.

Enzyme-entrapping membranes for enzyme sensors

A reliable method of physically immobilizing enzymes in cellulose triacetate (TAC) membranes was developed. The method has several advantages compared with analogous ones currently employed; it was possible to prepare enzyme sensors based on immobilized glucose oxidase (GOD) for determination of glucose in standard solutions and control sera, and based on GOD and invertase for determination of sucrose.

Membrane-entrapped cytochrome c: Electrochemical and kinetic studies

The redox kinetics and the electrochemical behaviour of cytochrome c entrapped in a cellulose triacetate membrane have been investigated with reference to the behaviour in solution. The results suggest that the membrane plays an important role in controlling the redox properties of the immobilized protein; diffusion of the reagents into the membrane is rate-limiting, and the nature of the working electrode has no effect on the observed electrochemical behaviour.

Membrane-entrapped cytochrome c: electrochemical and kinetic studies

The redox kinetics and the electrochemical behaviour of cytochrome c entrapped in a cellulose triacetate membrane have been investigated with reference to the behaviour in solution. The results suggest that the membrane plays an important role in controlling the redox properties of the immobilized protein; diffusion of the reagents into the membrane is rate-limiting, and the nature of the working electrode has no effect on the observed electrochemical behaviour.

High-Flux Synthetic Versus Cellulosic Membranes for β<sub>2</sub>-Microglobulin Removal During Hemodialysis, Hemodiafiltration and Hemoflitration

Efficient removal of beta 2 microglobulin (beta 2-M) in end-stage renal failure patients is a continuing preoccupation, as the incidence and severity of dialysis-associated amyloidosis are increasing. To evaluate comparative beta 2-M removal we studied six stable end-stage renal failure patients during high-flux 3-h haemodialysis, haemodia-filtration, and haemofiltration, using acrylonitrile, cellulose triacetate, polyamide and polysulphone capillary devices. The reduction of plasma beta 2-M, total removal in ultrafiltrate/dialysate, and beta 2-M sieving coefficients were measured by RIA. The results suggest that convection plays the major role in beta 2-M removal when high-flux synthetic membranes are used in combination with high blood flow rates. In contrast, using the cellulose triacetate membrane under investigation, beta 2-M removal is diminished when ultrafiltration rates are increased. Accordingly, in any future prospective study on the role of beta 2-M retention in the amyloidogenesis, it is recommended that high-flux synthetic membranes be employed rather than the type of high-flux cellulosic membranes used in this study. The modality with which these synthetic membranes are used is probably less important, as long as maximum convective transport rates are obtained. Under present conditions, this will imply haemofiltration or haemodiafiltration rather than haemodialysis.

The determination of choline in pharmaceutical preparations by means of an enzyme sensor

Previous attempts to produce enzymatic sensors for the determination of choline have involved the immobilization of choline oxidase enzyme in polymeric matrices and combining these with an oxygen electrode of the amperometric Clark type. Firstly, the enzyme was chemically immobilized in nylon [l, 21; subsequently a simpler immobilization technique was developed involving the physical entrapment of the enzyme in a cellulose triacetate membrane [3]. This method proved to be superior to the earlier immobilization techniques insofar as the enzyme is not denatured, the final enzymatic activity is higher and the operational life is longer. The method also was shown to be suitable for the analysis of biomedical matrices [4]. As many pharmaceutical preparations commercially available (injections and syrups), especially those active against anaemies, hypovitaminic states and haepatic diseases, contain low concentrations of choline, an attempt was made to apply the new sensors to the assay. The results obtained are presented here, discussed and compared with those given by a similar enzymatic method, but with spectrophotometric, rather than amperometric, detection.

Potentiometric ion- and bio-selective electrodes based on asymmetric cellulose acetate membranes

The potentiometric response properties of ammonium-, carbonate-, and proton-selective electrodes prepared by incorporating appropriate neutral carriers within novel asymmetric cellulose acetate membranes are reported. The membranes are formed by first casting a thin layer of cellulose triacetate without carrier, hydrolyzing one side of this film with base, and then on the other side casting a second layer of cellulose triacetate containing the membrane active components. The resulting asymmetric ion-selective membranes function equivalently, in terms of selectivity and response slopes, to non-asymmetric cellulose triacetate membranes and conventional poly(vinyl chloride)-based membranes. The hydrolyzed surface of the asymmetric membranes can be activated in aqueous solution with carbonyldiimidazole for the direct immobilization of proteins on the surface of the membranes, without loss in potentiometric ion-response. As an example, the immobilization of urease on the surfaces of ammonium- and carbonate-selective membranes yields potentiometric bio-selective urea-probes with desirable dynamic response properties.

Micro-biosensors for clinical analyses

Micro-biosensors for glucose and glutamate were constructed by using silicon fabrication technology. A micro-H 2O 2 electrode was used to make a micro-glucose sensor. Glucose oxidase was immobilized on an organic membrane, prepared by vapour deposition of γ-aminopropyltriethoxysilane (γ-APTES) and glutaraldehyde, and used for glucose determination in the range 0.1 to 10 mg dl −1. A micro-oxygen electrode was adapted to form a micro-glutamate sensor. Glutamate oxidase was immobilized on a cellulose triacetate membrane containing glutaraldehyde and triamine. A linear relationship was observed between the glutamate concentration, in the range 5 to 50 MM, and the decrease in current.

Plasma Collection Using Nafamostat Mesilate and Dipyridamole as an Anticoagulant

Nafamostat mesilate (FUT-175) is a strong protease inhibitor and is used as an anticoagulant in extracorporeal circulation. In the present study, we administered FUT and dipyridamole as anticoagulants during donor plasmapheresis, and the additional effect of dipyridamole was examined. In dogs weighing about 15 Kg, donor plasmapheresis was performed using a cellulose triacetate membrane plasmaseparator (PEX-15, Nipro), and 300 ml of filtrated plasma was obtained within 30 minutes. These dogs were divided into two groups, 50 mg/h of FUT alone was infused (group A, n = 10), and the same dose of FUT and 25 mg/h of dipyridamole were infused (group B, n = 5) during plasmapheresis. Changes of the coagulation system, blood cell counts and complement system were investigated. In clinical cases, an artificial liver support therapy using FUT as an anticoagulant was performed on 8 patients with acute liver failure, and blood compatibility was examined. In dogs, RBC counts and hematocrits were almost stable, but WBC counts were decreased to about 70% of the previous value. Platelets counts were about 60% and 80% of the previous value, in group A and group B, respectively, at the end of the plasmapheresis (P less than 0.01). Clotting factor VII was diminished to about 20% and 35% of the previous value in group A and B, respectively. In clinical cases, all patients received the plasma exchange combined with hemodialysis using FUT as an anticoagulant, and no distinct side effect was observed during plasma exchange.

Enzyme sensor for the determination of choline-containing phospholipids in some biological fluids.

A choline enzymatic-amperometric sensor, obtained by physical entrapment of choline oxidase in cellulose triacetate membranes, was used for the determination of choline-containing phospholipids in serum, bile and amniotic fluids. The results obtained are compared with those obtained using an analogous sensor, based on the chemically immobilised enzyme, and with the data obtained by an enzymatic-spectrophotometric method.

Effect of Plasticizer on Carrier-Mediated Transport of Zinc Ion through Cellulose Triacetate Membranes

Abstract In practical applications of liquid membranes containing a mobile camer, three main types of membranes have been studied: liquid surfactant, supported liquid, and solvent polymeric membranes (2-6). In these membranes the solvent polymeric membrane which consists of a polymer film containing a plasticizer generally exhibits a low ionic permeability compared with the other types of membranes, although it has a high stability and durability. This is because the transference of the carrier in the membrane is depressed by its high viscosity and high electrical resistance. Accordingly, the ionic permeability may be improved by selecting an appropriate plasticizer.

Ethanol sorption and partial molar volume in cellulose acetate films

The absorption characteristics of cellulose acetate (CA398) and cellulose triacetate membranes for ethanol vapor were determined by integrated optical techniques. Changes in the refractive index and film thicknesses are used to calculate the ethanol concentration within the membrane, to calculate the partial molar volume of sorbed ethanol as a function of ethanol concentration, and to estimate the average void volume of the dry film. The refractive index is shown to be very sensitive to the available void space within the membrane. The average total void space for the films considered here was less than 1% of the dry polymer volume. 22 references, 6 figures, 1 table.

セルローストリアセテート系限外ろ過膜の製造と溶質分離性

Cellulose triacetate ultrafiltration membranes were prepared using the casting solution consisted of formic acid, additives, and polymer. Effects of additives in casting solution on membrane performance was studied. The addition of water and inorganic salts in casting solution rendered to increase in water-permeability, but to decrease in solute retention. On the other hand, the solute retention of membrane was improved by using a solvent containing dichloromethane. Membrane separation performance were examined for various solutes, such as sacchrose, amino acid, and organic acids with low molecular weight. Saccharose and amino acids were well retained by cellulose triacetate membrane, but retention levels of membrane for organic acids and tetraethylene glycol were very poor. The retention of aromatic amino acids, such as DL-tyrosine and L-phenylalanine were less in comparision to the data of aliphatic amino acids

Cellulose triacetate membranes for seawater desalination

Experimental data on reverse osmosis using a sodium chloride solution by cellulose triacetate membranes are presented. The investigation involved studies on the composition of membrane casting solutions and their effects on the performance. A higher polymer concentration (11–13%) is found suitable for production of a uniform and highly salt rejecting membrane. Salt rejection of 99.0% and 4–5 GFD product water flux were obtained at 1000 psi operating pressure using 30,000 ppm TDS seawater in the initial experiments.

A field trial of reverse osmosis in the El Khanka desert, Egypt

Installation and operation of a reverse osmosis test facility at El Khanka Kaliobia, Egypt has been jointly arranged by the GKSS Forschungszentrum, West Germany and the National Research Centre, Egypt. The test plant, developed by the GKSS Research Centre, a plate system of nominal output of 45 m 3/d, has been in operation since January 1979. The present report considers only the results of the first three years of operation. Two prototype reverse osmosis modules developed by GKSS were tested, the G3 module during the first phase and the G4 module during the second phase. The two types of membranes used were a blend cellulose di- and tri-acetate membrane and a bentonite-stabilized cellulose acetate membrane.

The use of membrane filters applied directly to the surface of agar plates for the isolation of campylobacter jejuni from feces

Cellulose triacetate membrane filters applied directly to the surface of non-selective blood agar plates were found to be as effective as the use of antibiotic media in isolating Campylobacter jejuni from patients with diarrhea. This method was used in parallel with selective media in the examination of 1000 specimens of feces. Campylobacters were isolated from 56 specimens using all methods. The membrane filter method detected 50 (89%), 45 of which were C. jejuni, and selective media 45 strains of C. jejuni (80%). Membrane filters used in this way can result in the detection of most cases of campylobacter enteric infection and can be used by small laboratories with limited access to selective media. They may also facilitate the isolation of antibiotic sensitive campylobacters.

Characteristics of the Cellulose Triacetate Membrane for Hemofiltration

The Permeation characteristics of the cellulose triacetate membrane used for hemofiltration were studied and compared with other commercially available sheet type membranes. The critical solute fractionation profile of the cellulose triacetate membrane was very similar to that of a glomerular basement membrane. The cellulose triacetate membrane showed a typical gel concentration polarization with a protein solution; however, the surface of the membrane is considered to be relatively homogeneous for permeation based on the relation between fluxes of the protein solution and saline: the flux of the protein solution is not much less than that of saline. This result differs from that observed with other membranes. Because of these desirable characteristics the cellulose triacetate membrane is considered to be suitable as a membrane for a hemofiltration system.

Demineralization for reuse of coal conversion condensates

Download Hi-Res ImageDownload to MS-PowerPointCite This:Ind. Eng. Chem. Proc. Des. Dev. 1983, 22, 3, 496-503

ALKALI SAPONIFICATION REACTION OF CELLULOSE TRIACETATE MEMBRANE IN HETEROGENEOUS SYSTEM AND PERVAPORATION WITH THE REACTION

In heterogeneous system, the alkali saponification reaction of cellulose triacetate (CTA) membrane in the mixture of ethanol and water advanced with sharp moving boundary of reacted layer with a linear relationship of the thickness with the reaction time as in the case of ethylene-vinyl acetate copolymer membrane. Sorption and diffusion of H2O and C2 H5 OH under the pervaporation with the reaction were examined, and results were obtained as follows. Experimental values of permeation rates of H2O and C2H5OH through a partially saponified membrane agreed with those calculated by assuming the membrane to be a lamination of two layers of cellulose and CTA. For the pervaporation with the reaction, an equation was obtained. Where F is over all permeation rates for water or ethanol, k is the moving rate of the boundary front, l is the membrane thickness before the reaction and Pcell and PCTA are permeability constants for cellulose and CTA membrane, respectively. Plots of 1/F vs. t showed linear relationships for ethanol and water, respectively. From the results, the permeation constants for H2O and C2H5OH under the heterogeneous reaction were obtained. Diffusivity of alkali ion in the cellulose membrane was found 120 times larger than that in CTA membrane. Summarizing these results, it was concluded that the alkali saponification reaction under pervaporation advanced with a controlling step of boundary reaction. An analogy may be found between the reaction and the Case II type diffusion.

Quantitative determination of deoxyribonucleic acid from cells collected on filters

A method is described for the quantitation of cellular deoxyribonucleic acid from mammalian cells collected on cellulose triacetate membrane filters. DNA released from cells by sonication is fluorescently quantitated based on the DNA-dependent fluorescence enhancement of the anti-tumor antibiotic mithramycin. Pretreatment of filters with bovine serum albumin prior to sonication is necessary to prevent the loss of DNA-mithramycin fluorescence. The cellular DNA content in isolated capillary endothelium is 7.1 pg per cell and in isolated hepatocytes, 17.7 pg per cell.