Membrane flux

The pressure to be used for reverse osmosis depends on the salinity of the feedwater, the type of membrane, and the desired product purity. It ranges from about 1.5 MPa for low feed concentrations or high flux membranes, through 2.5—4 MPa for brackish waters, and to 6—8.4 MPa for seawater desalination. In desalination of brackish or sea water, typical product water fluxes through spiral-wound membranes are about 600—800 kg/m /d at a recovery ratio RR of 15% and an average salt rejection of 99.5%, where... 

High Flux Membrane Top Side Bottom Side... 

In order to obtain thin skinned, high flux membranes from PVA, several approaches were tried. The method presented in this article is reminiscent of the classical phase inversion method, which is widely applied in casting of asymmetric RO membranes. However, instead of using a gelling bath composed of a nonsolvent... 

Permeation was allowed to proceed for 90 min to equilibrate the membranes. This method permitted at least 10 mL of solution to permeate through even the low-flux membrane. Instead of taking the original concentration for the calculation of percent rejection of the solutes, the concentration after equilibration was used. 

R.W. Baker and H. Strathmann, Ultrafiltration of Macromolecular Solutions with High-flux Membranes, J. Appl. Polym. Sci. 14, 1197 (1970). 

Figure 11.9 Effect of metal concentration in the feed and product solution on flux. Membrane, microporous Celgard 2400/30% Kelex 100 in Kermac 470B feed, pH 2.5 product, 100 g/L H2SO4 [9]...

Most of the more recent research has focused on developing membrane materials with a better balance of selectivity and productivity (permeability) as that seems the most likely route for expanding the use of this technology. There appear to be natural upper bounds [9,10] on this tradeoff that limit the extent of improvement that can be realized by manipulating the molecular structure of the polymer used for the selective layer of high-flux membranes, at least in many cases. This has led to interest in nonpolymeric and so-called mixed-matrix materials for membrane formation [8] however, at this time, polymers remain the materials of choice for gas-separation... 

Flux. The film model (Equation 6.6) illustrates that increasing flux has an exponential effect on CP. If we accept that fouling is a consequence of CP the impact of excessive flux is obvious. As a result high flux membranes tend to be short lived and foul unless improved fluid management is able to enhance k. Selection of the appropriate flux and crossflow velocity is a trade-offbetween capital and operating costs (see cost of fouling below). 

Peces R, Pobes A. Effectiveness of haemodialysis with high-flux membranes in the extracorporeal therapy of life-threatening acute lithium intoxication. Nephrol Dial Transplant 2001 16(6) 1301-3. 

The use of LCVD or LGT in membranes is aimed at increasing the value of a for a set of permeants of interest. The increase of a, however, is achieved at the expense of the permeant throughput, i.e.. Pa and Pb both decrease by the application of LCVD layer. Therefore, the use of high-flux membrane or substrate is mandatory. In barrier applications, the selection of good barrier (low values of Ps) is mandatory because the barrier characteristic of a film can be expressed by f/P, where t is the thickness of film, and there is a limit in the increase of barrier characteristics by application of nanofilm. 

The permeation, selectivity, and flux variation with methanol concentration has been explained using the solubiUty parameter approach Copolymers of acrylonitrile with methyl methacrylate and vinyl acetate showed good selectivity and moderate flux Membrane (I) gave high selectivity and acceptable flux... 

Rousaud BE, Garcia JM, Camps EM, Cubells TD, Comamala MR. ACE inhibitors and anaphylactoid reactions to high-flux membrane dialysis (AN69) clinical aspects. Nephron 1992 60 487. 

In a 6-day-old neonate with a solitary hypodysplastic kidney, suspected sepsis, and acute renal insufficiency, venovenous hemodiafiltration with a high-flux membrane was successfully used to treat a 10-fold overdose of vancomycin (115). 

Li, N.N. Kuehne, M.A. Petersen, R.J. A novel high flux membrane. ICOM 99 the 1999 International Congress on Membranes Membrane Processes, Toronto, Canada, June 12-18, 1999 North American Membrane Society, 1999 Abstract Number 236. 

Perhaps through the introduction of free carboxylic acid groups, a much higher flux membrane was formed. This membrane, which was named NS-300, exhibited particularly high retention of salts having polyvalent anions. 

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