Saline, rejection

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... 

Nanofilters incorporate negative membrane charge for higher anion rejection. High feed salinities can passivate these charges and reduce anion retention. 

Reject Brine or High Saline Brackish Water... 

In the first instance, the roots of planta may take up all substances in solution without selection. But this action is not one of simple imbibition as in the case of sponges. Liebig-, in a recent memoir, maintains that the spongioles, in obtaining their supply of saline matter, exert a real decomposing action on certain Ill-defined compounds, which the saline mattar forms with the. insoluble constituents of the soil, Those substances which are conveyed to planta in solution are retained in greater or less quantity, or are entirely rejected when not fit For assimilation. 

For steady-state operation, the capacity of the ice in the melting unit to absorb heat isothermally is just equal to the heat of crystallization removed in freezing the ice. Thus another refrigeration machine, R2, is employed to transfer the additional heat rejected by Rt to the saline water mass, which, in this idealization, may be considered as having infinite heat-absorbing capacity at its ambient temperature, Tu. 

The basic elements of a new electrochemical approach to saline water demineralization under study at the University of Oklahoma for the past three years are two porous electrodes, one of which is responsive to cations and the other to anions. When an appropriate voltage is applied to such an electrode pair immersed in saline water, cations are removed by the former and anions by the latter. In the regeneration phase, reversal of voltage gives up these ions to a reject solution. 

Seawater has a salt concentration of 3.2-4.0%, depending on the region of the world. Because of this high salinity, only membranes with salt rejections of 99.3 % or more can produce potable water in a single pass. Application to seawater desalination of the first-generation cellulose acetate membranes, with rejections of 97-99 %, was limited. With the development of the polyamide hollow fine fibers and interfacial composites, suitable seawater membranes became available, and many plants have been installed. In general, membranes are not... 

The method has been modified in various ways by several authors. Cummings et al. (1960) recommended a sequential procedure with criteria for acceptance or rejection of test drugs. Kau et al. (1984) recommended a method for screening diuretic agents in the rat using normal saline (4 % body weight) as hydrating fluid. 

Tacrolimus, an immunosuppressant used to prevent rejection of liver and kidney transplants, is insoluble in water and is solubilized in Prograf to 5mg/ml with 20% Cremophor RH 60 and 80% ethanol and is administered by IV infusion after a 250-fold or a 1,000-fold dilution with saline or dextrose 5%. The dose of tacrolimus is up to 35 mg, which is 7 ml of Prograf, of which 1.4 ml is Cremophor RH60 per dose, representing the estimated maximum amount administered intravenously. 

The evidence of electrokinetic salt rejection by a microporous inorganic material was given by Jacazio et al. [63] based on the model of Osterle [26-28]. Experiments were carried out on the salt rejecting properties of compacted clay through which saline solutions were forced under high pressures. In accordance with the model the performance of the porous material was shown to depend on three main parameters the ratio of the Debye length to effective pore... 

Polysulfone. Polysulfone homo- (19) and copolymers have been formed into hollow fiber membranes for hemofiltration by solution extrusion, followed by coagulation and washing. Equilibrium water absorption by these membranes varies between 0.85 and 2.1 percent. The water-equilibrated polymers are glassy at room temperature. Sieving properties of copolymer hemofilters prepared with a 2-phenyl-2-phenoxy propane segment have been characterized (2). The hydrophobicity of this polymer is reflected in a significantly altered rejection spectrum in the presence of protein when compared to saline solutions. 

Figure 3 Rejection spectra of cellulosic (A) and polysulphone (B) membranes In saline (o) and plasma (e). See reference for methodology. Reproduced with permission from...

For rejection of tracer solutes out of saline solutions, the uniform-wall-flux restriction is not a problem, because the axial pressure drop is generally less than 10% of the average transmem-... 

Graphs for Equations 15, 16, and 20 are shown in Figure 2, and for Equation 17 in Figure 3. Horizontal lines in Figure 2 represent the asymptotic limit for C /C for an experiment with a given P6cl6t number. For example, for a rejection experiment of myoglobin from saline solution D = 0,172 x 10 cm/sec, r =... 

Working Equations for Rejection Experiments in Saline. Raw da a from the rejection experiments are (total filtrate rate, cm /sec), Qg (total inlet feed stream low rate, cm /sec), C (feed stream inlet concentration, g/cm ), and C (average fiitrate concentration, g/cm ). R, is calculated acco ding to Equation 8,... 

Rejection Coefficients for Protein Ultrafiltration Experiments. Since the data for ultrafiltration rates seem to imply the condition of uniform wall flux, the calculation procedure for finding R for these experiments was identical with that used for saline solutions. No doubt the dlffusivity of the small solutes within... 

Table II, typical data of rejection versus J are given for four solutes in saline and serum systems. For myoglobin and cyto-...

The effect of serum on rejection of solutes, as compared with rejection measured out of saline, can be addressed in light of data for cellulosic membranes. Figures 10 and 11 demonstrate an effect consistently observed for the solutes myoglobin and cytochrome C. The observed and corrected rejection values fell off at approximately J >0.6 x 10 cm/sec from a plateau when saline was the solvent, whereas in serum the R versus J graphs were as predicted from the Spiegler-Kedem equation. The relative effects of serum or BSA on R, , and on resultant values for a... 

It seems clear from the rejection and ultrafiltration data that there is no appreciable protein adsorption on the cellulosic fibers. The transport properties measured in saline are of good predictive value for both serum and BSA experiments. 

Myoglobin, cytochrome-C, inulin, and vitamin B-12 were the solutes studied in saline, calf serum, and BSA systems at 37 C and pH 7.4. Observed solute rejections were corrected to intrinsic values by using uniform-wall-flux boundary layer theory for the developing and fully-developed asymptotic regions. The Splegler-Kedem equation ( ) for rejection versus volume flow was used to calculate reflection coefficients and diffusive permeabilities for each solute. There was no significant difference between rejection parameters measured in saline and protein solutions. 

Dynamically-formed hyperfiltration membranes of the ZrOg polyacrylate type on porous stainless steel were used in two high volumetric recovery applications. The first is the separation of dyes from a saline dye manufacturing process effluent and the second the renovation of wash water from a dye range for reuse. The dependence of the performance characteristics on recovery is described and discussed. Separation factors (dye from salt) in the first system are large and increase with concentration in two cases, but not in a third. Acceptable rejections and fluxes for reuse of the wash water were obtained to recoveries of O.96 in the second system. The fluxes are concentration dependent. 

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