Reverse osmosis analysis

Dandavati, M S., Doshi, M. R., and Gill, W. N. (1975). Hollow fiber reverse osmosis Experiments and analysis of radial flow systems. Chem. Eng. Sci., 30, 877-886. 

Gupta, S. K. (1987). Design and analysis of a radial-flow hollow-fiber reverse-osmosis system. Ind. Eng. Chem. Res. 26, 2319-2323,... 

The thermodynamic approach does not make explicit the effects of concentration at the membrane. A good deal of the analysis of concentration polarisation given for ultrafiltration also applies to reverse osmosis. The control of the boundary layer is just as important. The main effects of concentration polarisation in this case are, however, a reduced value of solvent permeation rate as a result of an increased osmotic pressure at the membrane surface given in equation 8.37, and a decrease in solute rejection given in equation 8.38. In many applications it is usual to pretreat feeds in order to remove colloidal material before reverse osmosis. The components which must then be retained by reverse osmosis have higher diffusion coefficients than those encountered in ultrafiltration. Hence, the polarisation modulus given in equation 8.14 is lower, and the concentration of solutes at the membrane seldom results in the formation of a gel. For the case of turbulent flow the Dittus-Boelter correlation may be used, as was the case for ultrafiltration giving a polarisation modulus of ... 

The above equations show that for a reverse osmosis system specified In terms of y, 9, and X, any one of the six quantities (performance parameters) C], C2, C3, C3, X or X or T, and A uniquely fixes all the other five quantities (112). Further, since the relationships represented by the set of eq 34 to 41 Involve 8 equations with 12 unknowns, namely, y, 9, X, Z, A, C-j, C2, C2, C3, C3, C3 and X or X or T, by fixing any four Independent quantities Included In the above unknowns, eq 34 to 41 can be solved simultaneously to obtain the remaining 8 quantities. The utility of this approach to system analysis for reverse osmosis process design and predicting the performance of reverse osmosis modules Is Illustrated In detail In the literature (6d,105,107,108,111,112,113). 

In all the foregoing discussion on reverse osmosis transport, system analysis and process design, no new chemical engineering principle Is Involved. But the manner In which the known principles are combined and expressed Is new the kind of results arising from such expressions Is new and the direction such approach sets for future work on the subject Is also new, all of which open a new area of chemical engineering. 

The technology developer, Atomic Energy of Canada Limited (AECL), has compiled cost estimates (in 1994 U.S. dollars) for the CHEMIC process based on treatment of a simulated waste solution contaminated with metals (cadmium and lead at feed concentrations from 1 to 5 mg/liter) and strontium-90 [from 1000 to 2000 becquerel per liter (Bq/liter)]. The target treatment level is <0.014 mg/liter lead, <0.02 mg/liter cadmium, and <10 Bq/liter strontium-90. See Table 1 for estimates associated with this cost analysis. The AECL analysis indicated that costs of the CHEMIC process compared favorably with the estimated costs for treatment using reverse osmosis or fixed-bed ion exchange. 

A Fundamental Approach to Reverse-Osmosis Concentration and Fractionation of Organic Chemicals in Aqueous Solutions for Environmental Analysis... 

T HE SEPARATION, CONCENTRATION, AND FRACTIONATION of organic solutes in aqueous solutions by reverse osmosis are of practical interest from the points of view of water purification and collection of samples for environmental analysis. Although many experimental data on the separation of organic solutes are available in the literature (1-2), very few fundamental works have been accomplished so far. We have been studying this subject in the framework of the preferential sorp-... 

Reverse-Osmosis Experiments. All reverse-osmosis experiments were performed with continuous-flow cells. Each membrane was subjected to an initial pure water pressure of 2068 kPag (300 psig) for 2 h pure water was used as feed to minimize the compaction effect. The specifications of all the membranes in terms of the solute transport parameter [(Dam/ 6)Naci]> the pure water permeability constant (A), the separation, and the product rate (PR) are given in Table I. These were determined by Kimura-Sourirajan analysis (7) of experimental reverse-osmosis data with sodium chloride solution at a feed concentration of 0.06 m unless otherwise stated. All other reverse-osmosis experiments were carried out at laboratory temperature (23-25 °C), an operating pressure of 1724 kPag (250 psig), a feed concentration of 100 ppm, and a feed flow rate >400 cmVmin. The fraction solute separation (/) is defined as follows ... 

Reverse osmosis for concentrating trace organic contaminants in aqueous systems by using cellulose acetate and Film Tec FT-30 commercial membrane systems was evaluated for the recovery of 19 trace organics representing 10 chemical classes. Mass balance analysis required determination of solute rejection, adsorption within the system, and leachates. The rejections with the cellulose acetate membrane ranged from a negative value to 97%, whereas the FT-30 membrane exhibited 46-99% rejection. Adsorption was a major problem some model solutes showed up to 70% losses. These losses can be minimized by the mode of operation in the field. Leachables were not a major problem. 

Because the application of NMR spectroscopy to environmental samples is relatively new, we focused our studies on the identification and characterization of DOP by 31P FT-NMR spectroscopy. Ultrafiltration and reverse osmosis concentration techniques were employed to increase the dissolved organic phosphorus concentrations to the detection level of 31P FT-NMR techniques (approximately 10-20 mg of P/L). With these concentration methods a DOP concentration factor of up to 2000 is obtainable. This chapter reports the use of 31P FT-NMR spectroscopy in the analysis of DOP. In... 

Sagiv, A. and Semiat, R. (2004) Analysis of parameters affecting boron permeation through reverse osmosis membranes. Journal of Membrane Science, 243 (1—2), 79-87. 

Perhaps some idea of the power of the gas chromatography-mass spectrometry approach to the analysis of organic micropollutants can be gauged by the work of Coleman et al. [134] on mutagenic extracts of potable water. Samples of the water (1818L) were concentrated to a small volume using reverse osmosis and lyophilisation. The concentrates were then fractionated by sequential extraction with petroleum ether, diethyl... 

S. Jain, S.K. Gupta, Analysis of modified surface pore flow model with concentration polarization and comparison with Spiegler-Kedem model in reverse osmosis system, J. Membr. Sci. 232 (2004) 45-61. 

Kimura, S. and S. Sourirajan, "Analysis of Data in Reverse Osmosis with Porous Cellulose Acetate Membranes Used," AIChE Journal, 13, No. 3,1967. 

ROSA [Reverse Osmosis System Analysis] 6 only projects reverse osmosis and nanofiltration system performance from a User-controlled set of data input and design decisions. The... 

Dow Water Solutions-FilmTec (Minneapolis, MN) www.dow.com Reverse Osmosis System Analysis (ROSA)... 

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