Membrane utilization

The geometries for asymmetric mixed-matrix membranes include flat sheets, hollow fibers and thin-fihn composites. The flat sheet asymmetric mixed-matrix membranes are formed into spirally wound modules and the hollow fiber asymmetric mixed-matrix membranes are formed into hollow fiber modules. The thin-film composite mixed-matrix membranes can be fabricated into either spirally wound or hollow fiber modules. The thin-film composite geometry of mixed-matrix membranes enables selection of different membrane materials for the support layer and low-cost production of asymmetric mixed-matrix membranes utilizing a relatively high-cost zeolite/polymer separating layer on the support layer. 

Dispersion free extraction in hollow fiber (HF) membrane utilizes immobilized liquid-liquid interface at the pore mouth of a microporous membrane to effect phase to phase contact and the mass transfer process. HF module can be con-... 

In a 1991 study by van Reis et al. (5), a filtration operation as applied to harvest of animal cells was optimized by the use of dimensional analysis. The fluid dynamic variables used in the scale-up work were the length of the fibers (L, per stage), the fiber diameter (D), the number of fibers per cartridge (k), the density of the culture (p), and the viscosity of the culture (p). From these variables, scale-up parameters such as wall shear rate (y ) and its effect on flux (L/m /h) were derived. Based on these calculations, an optimum wall shear rate for membrane utilization, operating time, and flux was found. However, because there is no single mathematical expression relating all of these parameters simultaneously, the optimal solution required additional experimental research. 

The allowable current density—normality ratio for electric membrane operation has been approximately doubled by an improved tortuous path spacer with strap turbulence promoters and by operation at higher pressures up to 60 p.s.i. As a result, twice as much water can now be demineralized per square foot of membrane utilized and/or greater demineralization achieved per pass in electric membrane units. One practical result of this development is a new continuous-flow, two-stage single-stack demineralizer which will provide 93% demineralization at a capacity of 5000 gallons per day and 72% demineralization at a capacity of 30,000 gallons per day. These units produce from 67 to 150% more water per unit membrane area than previously used automatic batch-recirculating units and are far simpler in construction and operation. 

Stephenson, R.C., and Clarke, S. (1990). Identification of a C-terminal protein carboxyl methyltransferase in rat liver membranes utilizing a synthetic farnesyl cysteine-containing peptide substrate. J Biol Chem 265 16248-16254. 

Dalven PI, Hildebrandt JR, Shamir A, Faccetti AJ, Hodgins FT, and Gregorh HP. Acrylonitrile-hased copolymers S3mthesis, characterization, and formation of ultrafiltration membranes utilized for the immobiUzation of proteins. J. Appl. Polym. Sci. 1985 30 1113-1132. 

Kakoi T, Goto M, and Nakashio F. Separation of platinum and palladium by bquid surfactant membranes utilizing a novel bi-functional surfactant. J Memb Sci 1996 120 77-88. 

Permeable gas separation membranes utilize differences in solubility and diffusion of different gas components in polymer materials. In recent years membrane-based technologies have gained increasing importance in gas processing. Typical applications are CO2 removal from natural gas or hydrogen recovery from synthesis gas. The degree of selectivity between different gas components depends on the membrane used so that it is necessary to contact the manufacturers for a concrete project. Membrane separation units are usually supplied skid mounted. 

A quite different approach from that of colloidal sols in the preparation of sol-gel derived membranes utilizes polymeric sols. In this category of sols the dispersed phase results from the hydrolysis and condensation of metal organic precursors in organic media. In most cases this process deals with the polymerization of metal alkoxides in alcohol according to the following reactions ... 

M.F. Carolan, P.N. Dyer, J.M. LaBar Sr. and R.M. Thorogood, Process for restoring permeance of an oxygen-permeable ion transport membrane utilized to recover oxygen from oxygen-containing gaseous mixtures. US Patent 5,240,473,1993. 

From a customer s point of view, membrane utilization is extremely important. Having invested in a membrane filtration plant, he must consider the following points carefully ... 

The large number of papers necessitated publishing the symposium in two volumes. Volume I describes the desalination and salt-rejecting hyperfiltration membranes. Volume II covers hyper- and ultrafiltration membrane utilization in the following areas food, medicine, pulp, paper, and textile industries, oily waste stream purification, and in the separation of gases, polymers, organic solutes, and biopolymers. 

The Nafion membranes utilized in the early 1970 s produced caustic soda concentrations of 10-15wt% at electrolytic power consumptions of approximately 3450 KWH/MT NaOH. Advancements in the technology of membranes by duPont, Asahi Glass Co., and Asahi Chemical Co., Tokuyama Soda Co., have achieved membranes that today can produce caustic soda concentrations of 28-40wt% with caustic current efficiency well over 90% for long term operations. 

Rickettsiae. Rickettsiae are microorganisms that have characteristics common to both bacteria and viruses. Like bacteria, they possess metabolic enzymes and cell membranes, utilize oxygen, and are susceptible to broad-spectrum antibiotics. They resemble viruses in that they grow only within living cells. 

Groot et al [3.86] investigated the technical feasibility of five reactive separation technologies (fermentation coupled to stripping, adsorption, liquid-liquid extraction, pervaporation, and membrane solvent extraction). They concluded that liquid-liquid extraction and pervaporation reactive separation processes show the greatest potential, with PVMBR systems particularly attractive due to their operational simplicity. Membranes utilized include silicone [3.76, 3.77, 3.74, 3.87, 3.75, 3.85, 3.88], supported liquid membrane systems [3.87, 3.89], polypropylene [3.70], and silicalite filled PDMS membranes [3.90, 3.91]. The results with PVMBR systems have been very promising. 

Schematic drawing illustrating the principle of Donnan dialysis by showing the transport Cu " " -ions through a cation-exchange membrane utilizing an electrical potential build up by the flux of H+-ions...

Three techniques have been used for the manufacture of the membranes utilized in the ezperimoats discussed here. The first technique involved manufacturing a sintered ceramic matrix of MgO without electrolyte present and then wicking the molten electrolyte into the matrix by capillaiy action. 

The above-mentioned examples all used proteins such as GOx and Con A. Exposure of these proteins and peptides to the body may cause an undesirable immime response upon contact. Therefore, these naturally derived proteins and peptides, and their whole systems, should be separated from the body using semi-permeable membranes. Utilization of totally S3m-thetic polymer systems would be a versatile choice for the construction of new glucose-responsive insidm-release devices. 

---