Hollow fiber membrane based separation applications

Pabby, A.K. and Sastre, A.M. (2006) Hollow-fiber membrane based separation technology performance and design perspectives, in Solvent Extraction and Liquid Membranes Fundamental and Application in New Materials (eds Cortina and Aguilar), Marcel Dekker, New York. 

A.K. Pabby, Hollow fiber membrane based technology and pressure driven membrane processes in nuclear fuel cycle Current status and challenges, in Proceedings of Theme Meeting onMembrane Separation for Fuel Cycle Applications, BARC, Mumhai, India, Septemher 16-18, 2013, p. 8. 

In liquid separation, hollow fiber membranes based on PBI have shown excellent performance for pervaporation dehydration of organic liquids. For example, a dual layer PEI-PBI hollow fiber membrane with an outer selective layer of PBI showed better performance than most other polymeric membranes in pervaporation dehydration of ethylene glycol. Sulfonation modifications of PBI membranes have demonstrated excellent separation efficacies in the dehydration of acetic acid. Studies have shown that PBI hollow fiber membranes were effective in separating chromates from solutions. Also, PBI nanofiltration hollow fiber membranes are promising candidates as forward osmosis membranes. In gas separation, recent studies sponsored by the Department of Energy at Los Alamos National Laboratories and SRI International demonstrated potential applications of PBI membranes in carbon capture and Hj purification from synthesis gas streams at elevated temperatures. H2/CO2 selectivity > 40 has been achieved at H2 permeability of 200 GPU at 250°C. ... 

The extraction of metals based on a membrane contactor system with conventional solvents is a process widely studied using different configurations, extractants, and extraction solvents. One of the upcoming applications of membrane contactors is supercritical extraction. This process is called porocritical extraction. Porocritical process or porocritical extraction is a commercial supercritical fluid extraction (SFE) technique that utilizes an hollow fiber membrane contactor (HFMC) to contact two phases for the purpose of separation. As an improvement, the extraction of Cu + from aqueous solutions by means of dense gas extraction was achieved by using a hollow fiber membrane contactor device [7]. The authors... 

Hollow liber membranes are numerous small hollow fibers with semi-permeable walls, and are assembled within a cylindrical shell/jacket to function as a bioreactor. One of the clinical applications of hoUow fiber bioreactors is the hemodialyzer. These hollow fiber membranes are produced by solution-based processing method by solvent phase separation. This process has been used to produce filtration membranes in the past [11], and is now being used to produce tissue engineering scaffolds [12-14]. 

Reverse Osmosis. This was the first membrane-based separation process to be commercialized on a significant scale. As described previously, the breakthrough discovery that made reverse osmosis possible was the development of the Loeb-Sourirajan as5mimetric cellulose acetate membrane. This membrane made desalination by reverse osmosis practical within a few years commercial plants were installed. Currently, the total worldwide market for reverse osmosis membrane modules is about 300 million/year, split approximately between 15% hollow-fiber and 85% spiral-woimd modules. The general trend of the industry is toward spiral-wound modules for this application, and the market share of the hollow-fiber products is falling (75). 

One unique application area for PSF is in membrane separation uses. Asymmetric PSF membranes are used in ultrafiltration, reverse osmosis, and ambulatory hemodialysis (artificial kidney) units. Gas-separation membrane technology was developed in the 1970s based on polysulfone hollow-fiber membranes. The PRISM (Monsanto) gas-separation system based on this concept has been a significant breakthrough in gas-separation technology (see Membrane Technology). Additional details are available on the use of polysulfone in membrane separations (45), as well as gas transport properties of polysnlfone and polyethersulfone (46-50). 

Hollow fiber membranes (HFMs) formed via phase inversion methods exhibit specific physicochemical characteristics and generally favorable surface and mechanical properties. Due to these properties the HFMs can be used in diverse applications including ultrafiltration, gas separation, dialysis, cell culture, bioreactors, and tissue engineering. Most artificial kidneys are based on hollow fiber membranes. Blood is circulated through the center of the fiber, while isotonic saline, the dialysate, is pumped countercurrently around the outside of the fibers. Urea, creatinine, and other low-molecular weight metabolites in the blood diffuse across the fiber wall and are removed with the saline solution. 

Extractive fermentation is a relatively new technology that combines the fermentation process with product separation from beer. This process has been applied to commercial production of both lactic acid and ethanol, and experimental results suggest application to the propionic acid process will overcome some of the barriers indicated above. Solichien et al. (1995) examined a series of microporous membranes and polymer films for performance in membrane-based extraction of propionic and acetic acids with a range of organic solvents and acid-complexing carriers. The hollow-fiber membrane extractors, Celgard X20-400 or X-30, were found to be most satisfactory for laboratory-scale fermentations. Each extractor consisted... 

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