Reverse osmosis review

J. Scott, ed.. Desalination of Seawater by Reverse Osmosis, Pollution Technology Review No. 75, Noyes Data Corp., Park Ridge, N.J., 1981. 

The pressure difference between the high and low pressure sides of the membrane is denoted as AP the osmotic pressure difference across the membrane is defined as Att the net driving force for water transport across the membrane is AP — (tAtt, where O is the Staverman reflection coefficient and a = 1 means 100% solute rejection. The standardized terminology recommended for use to describe pressure-driven membrane processes, including that for reverse osmosis, has been reviewed (24). 

Transport Models. Many mechanistic and mathematical models have been proposed to describe reverse osmosis membranes. Some of these descriptions rely on relatively simple concepts others are far more complex and require sophisticated solution techniques. Models that adequately describe the performance of RO membranes are important to the design of RO processes. Models that predict separation characteristics also minimize the number of experiments that must be performed to describe a particular system. Excellent reviews of membrane transport models and mechanisms are available (9,14,25-29). 

Singh, Rajindar (M.A.E. Environmental Technologies). A Review of Membrane Technologies Reverse Osmosis, Nanofiltration and Ultrcfiltration. Ultrapure Water, Tall Oaks Publishing, Inc., USA, March 1997. 

Soltanieh, M. and Gill, W. N. Chem. Eng. Commun. 12 (1981) 279. Review of reverse osmosis membranes and transport models. 

This volume is the result of a symposium honoring Drs. Sidney Loeb and S. Sourirajan on the 20th anniversary of their discovery of the first functionally useful reverse osmosis membrane. Both of these esteemed gentlemen participated as plenary speakers and described not only how their membrane originated but also reviewed membrane theory and put the membrane field into present and future perspective. 

In bioprocesses, a variety of apparatus that incorporate artificial (usually polymeric) membranes are often used for both separations and bioreactions. In this chapter, we shall briefly review the general principles of several membrane processes, namely, dialysis, ultrafiltration (UF), microfiltration (MF), and reverse osmosis (RO). 

In either approach, the selection of isolation (e.g., solvent extraction, adsorption on carbon and synthetic resins) and concentration (e.g., lyophilization, vacuum distillation, reverse osmosis, ultrafiltration) methods is of paramount importance in properly assessing the potential toxicity of waterborne organics. A comprehensive literature review on the development and application of these and other methods to biological testing has recently been published by Jolley (3). 

Polyamides and their analogue are also effective for the selective membranes and there have been developed many kinds of permselective membranes. In early 1960 s, du Pont started to investigate the membranes for demineralization of water by reverse osmosis. After screening polymers, aromatic polyamides and polyhydrazides were shown to have superior properties9-11. In the present review various polyamides and their analogue are in focus as barrier materials for membranes, and their permeative characteristics will be discussed from the view point of their chemical structures. 

The mere preparation of porous membranes is accompanied with a noticeable decrease of permselectivity 11, which is undesirable for reverse osmosis and ultrafiltration, A thin dense layer should be adopted to attain a high permeability with — out the decrease of permselectivity, but this necessarily decreases the mechanical strength. This conflict is largely resolved by the construction of asymmetric or composite membranes as described also in the present review. 

Approximately one-half of the reverse osmosis systems currently installed are desalinating brackish or seawater. Another 40 % are producing ultrapure water for the electronics, pharmaceutical, and power generation industries. The remainder are used in small niche applications such as pollution control and food processing. A review of reverse osmosis applications has been done by Williams et al. [52],... 

Furukawa, D.H.(Sept. 1997) A review of seawater reverse osmosis. IDA Desalination Seminar, Cairo, Egypt. 

Soltanieh, Mohammad, and William N. Gill, "Review of Reverse Osmosis Membranes and Transport Models," Chemical Engineering Communications, 12, No.4,1981. 

Williams, Michael E., "A Brief Review of Reverse Osmosis Membrane Technology," white paper, EET Corporation and Williams Engineering Services Company, Inc., www.eetcorp.com/heepm/RO ReviewE. pdf, 2003. 

Much effort has been expended in attempting to use membranes for separations. Reverse osmosis membranes are used worldwide for water purification. These membranes are based on size selectivity depending on the pores used. They do not have the ability to selectively separate target species other than by size. Incorporation of carrier molecules into liquid membrane systems of various types has resulted in achievement of highly selective separations on a laboratory scale. Reviews of the extensive literature on the use of liquid membrane systems for carrier-mediated ion separations have been published [15-20]. A variety of liquid membranes has been studied including bulk (BLM), emulsion (ELM), thin sheet supported (TSSLM), hollow fiber supported (HFSLM), and two module hollow fiber supported (TMHFSLM) types. Of these liquid membranes, only the ELM and TMHFSLM types are likely to be commercialized. Inadequacies of the remaining... 

Sincere, A. P. (1989). Reverse osmosis removal of organic compounds—A preliminary review of literature. Contract No. DAALO -86-D-0001. U.S. Army Biomedical Research and Development Laboratory, Fort Detrick, Frederick, MD, 6 0. 

Goosen M.F.A., Sablani S.S., Al-Hinai H., Al-Obeidani S., Al-Belushi R., and Jackson D., FouUng of reverse osmosis and ultrafiltration membranes A critical review. Separation Science and Technology 39(10) 2004 2261-2298. 

The twenty chapters included in this volume can be conveniently divided into the following groups review plasma polymerization of hydrocarbons plasma polymerization of fluorocarbons plasma polymerization of organometallic systems plasma-initiated polymerization and applications of plasma polymerization. Though the emphasis of this Symposium is on the fundamental aspects of plasma polymerization, we should not lose sight of the fact that it is the potential applications of this technique that has stimulated the efforts in basic research. Potential applications for plasma-polymerized films include membranes for reverse osmosis, protective coatings for optical components, and insulating layers for semiconductors. 

Several methods have been explored for the economical recovery of lactic acid from fermentation broth including extraction with solvent, electrodialysis, ion-exchange adsorption (see [14] for review), and reverse osmosis [15]. Wang et al. 

Cadotte ( ) presents a comprehensive review of the development of the composite membrane with emphasis on the pros and cons of the four preparation methods mentioned above and on the polymer chemistry Involved. Cadotte points out that while each of the four methods continues to receive some attention, the Interfaclal polymerization method appears to be the most versatile. This method can be used to produce skin layers from polyamines, polylmlnes, polyurethanes, polyesters and other polymers. Elsewhere In this volume, Lee and co-workers (45) discuss the advantages and problems associated with using these composite membranes for ethanol-water separations via counter-current reverse osmosis. Also, Cabasso (44) discusses double-layer composite membranes. 

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