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Pure water permeation

A limitation to the more widespread use of membrane separation processes is membrane fouling, as would be expected in the industrial application of such finely porous materials. Fouling results in a continuous decline in membrane penneation rate, an increased rejection of low molecular weight solutes and eventually blocking of flow channels. On start-up of a process, a reduction in membrane permeation rate to 30-10% of the pure water permeation rate after a few minutes of operation is common for ultrafiltration. Such a rapid decrease may be even more extreme for microfiltration. This is often followed by a more gradual... [Pg.376]

The value of /, PR, and the pure water permeation rate (PWP) for a given area of film surface (13.2 cm2 in this work) were determined under the specified experimental conditions. The data on PR and PWP are corrected for 25 °C. Concentrations of NaCl were determined by conductance measurement, whereas concentrations of organic solutes were determined by the Beckman total carbon analyzer model 915-A. [Pg.146]

PWP pure water permeation rate through given area of membrane surface (kg/h)... [Pg.165]

Pure water permeability Lp was obtained from the experiment of pure water permeation using Eq. (9), in which the osmotic pressure difference All is zero. [Pg.125]

This extends the previous work (I ) In which the Lennard-Jones type surface potential function and the frictional function representing the Interfaclal forces working on the solute molecule from the membrane pore wall were combined with solute and solvent transport through a pore to calculate data on membrane performance such as those on solute separation and the ratio of product rate to pure water permeation rate in reverse osmosis. In the previous work (1 ) parameters Involved in the Lennard-Jones type and frictional functions were determined by a trial and error method so that the solutions in terms of solute separation and (product rate/pure water permeation rate) ratio fit the experimental data. In this paper the potential function is generated by using the experimental high performance liquid chromatography (HPLC) data in which the retention time represents the adsorption and desorption equilibrium of the solute at the solvent-polymer interface. [Pg.315]

All symbols used are defined at the end of the paper. The ratio of product rate to pure water permeation rate, (PR)/(PWP), is obtained from the relation,... [Pg.320]

When the concentrate batches were added flux declined rapidly. This could be due to an increased osmotic pressure, increased viscosity of the solutions, or adsorption of material on the membrane or, more likely, a combination of aU of these effects. No precipitation occurred in the tank. After the last batch was concentrated, the RO was rinsed with pure water (permeate). Flux was strongly influenced by temperature, which was responsible for most flux changes occurring during usual operation. The graph showing temperature dependence is shown in Figure A1.8. [Pg.322]

Xu et al. [11] studied the effects of both N,N-dimethylacetamide (DMAc) as a solvent additive in an internal coagulant (water) and acetic acid as a nonsolvent additive in a dope solution (PEI in DMAc) on the morphology and performance of poly(etherimide) (PEI) hollow fiber membranes for UF. Cross-sectional pictures were taken by SEM. The authors observed nodular structures on the inner and outer edges of the cross section when the amount of the acetic acid in the dope solution was increased. Pure water permeation flux increased when the nodules appeared. [Pg.144]

Table 3. Change in PVP Content During Pure-Water Permeation Experiment (88)... Table 3. Change in PVP Content During Pure-Water Permeation Experiment (88)...
Pure-water permeation lime (h) Surface PVP concentration, C, (wt%) ... [Pg.122]

CONCENTRATION PROHLE IN A LAMINAR FLOW CHANNEL where v is ihc pure-water permeation velocity. [Pg.318]

Write down the governing equations for (a) pure water permeation (b) pressure inside the fiber bore. Identify the boundary conditions in terms of P,. Solve the problem of obtaining the expressions for water permeation velocity as a function of fiber length and the pressure inside the fiber bore. [Pg.810]

The flat sheet membranes were tested using aqueous solutions containing nonionic macromolecules, that is, PEG or Dextran of various molecular weights. First, pure water permeation flux was measured. Subsequently, the solute retention test was performed with PEG or Dextran of increasing molecular weights. The initial feed solute eoncentration was noted and the solute separation was calculated using Eq. (4) ... [Pg.127]

Figure 33.5 Compressive strain (left ordinate) and permeation rate (right ordinate) as a function of operating time for pure water permeation through a Dow BW-30 RO flat-sheet membrane at 4.1 MPa and 23°C. Figure 33.5 Compressive strain (left ordinate) and permeation rate (right ordinate) as a function of operating time for pure water permeation through a Dow BW-30 RO flat-sheet membrane at 4.1 MPa and 23°C.
A potentially very useful apphcation of UTDR is to design membranes that offer improved resistance to compaction. Kelley et al. (2002) smdied the effect of cross-linking on the compaction resistance of cellulose-acetate membranes. Figure 33.6 shows the compressive strain as a function of time for pure water permeation through a cellulose-acetate membrane at 4.1 MHz that has been exposed for different periods of time at 23°C to a titanium-isopropoxide cross-hnking agent. Sufficient cross-linking time can reduce the compressive strain by 65% and nearly totally eliminate the elastic compaction. [Pg.887]

Figure 33.6 Compressive strain as a function of time for pure water permeation through a cellulose acetate membrane at 4.1 MHz that has been exposed for different periods of time at 23°C to a titanium-isopropoxide cross-linking agent. Figure 33.6 Compressive strain as a function of time for pure water permeation through a cellulose acetate membrane at 4.1 MHz that has been exposed for different periods of time at 23°C to a titanium-isopropoxide cross-linking agent.
Saljoughi, E., Sadrzadeh, M., and Mohammadi, T. 2009. Effect of preparation variables on morphology and pure water permeation flux through asymmetric cellulose acetate membranes. J. Memb. Sci. 326 627-634. [Pg.190]

FIGURE 10.6 Pure water permeation (transmembrane pressure = 1 bar) and the outer diameters of the membranes sintered at different temperatures. (Data from Lee, M. et al., Journal of Membrane Science, 461, 39-48, 2014.)... [Pg.330]

Several systematic studies on the effect of substrate membranes were conducted at IMRI recently. Singh et al. coated laboratory made PES membranes of different pore sizes with SPPO (intrinsic viscosity of base PPO polymer, 0.46 dL/g, lEC, 2.0 meq/g) to prepare SPPO TFC membranes. The substrate membrane was coated by dip-coating using 1 % SPPO solution in methanol. The pure water permeation flux and molecular weight cut-off data before and after the coating of SPPO polymer is shown in Table 8. [Pg.196]

Table 8. Pure water permeation flux and molecular weight cut-off before and after coating of substrate membranes with a SPPO layer ... Table 8. Pure water permeation flux and molecular weight cut-off before and after coating of substrate membranes with a SPPO layer ...
Operating pressure, 150 psig Feed NaCl concentration, 500 ppm feed MgS04 concentration, 1500 ppm butoxyethanol/isopropyl alcohol ratio Pure water permeation flux Product permeation flux in the presence of solute... [Pg.203]

Feng treated commercial PES membranes with a butoxyethenol/isopropyl alcohol mixture (40/60) under the same condition as they were coated with SPPO polymer solution. The pure water permeation flux and MWCO were then determined at 50 psig. Pure water permeation flux and MWCO of the membranes before and after the treatment are listed in Table 13. [Pg.203]


See other pages where Pure water permeation is mentioned: [Pg.262]    [Pg.464]    [Pg.22]    [Pg.44]    [Pg.51]    [Pg.55]    [Pg.56]    [Pg.177]    [Pg.179]    [Pg.262]    [Pg.220]    [Pg.316]    [Pg.337]    [Pg.337]    [Pg.173]    [Pg.208]    [Pg.129]    [Pg.121]    [Pg.145]    [Pg.240]    [Pg.280]    [Pg.310]    [Pg.66]    [Pg.810]    [Pg.887]    [Pg.330]    [Pg.216]   
See also in sourсe #XX -- [ Pg.196 , Pg.198 , Pg.203 , Pg.216 , Pg.218 , Pg.227 ]




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