Ultrafiltration hollow fiber

Polysulfone hollow fibers, composite, 76 17 Polysulfone membranes, 75 811 Polysulfones, 70 202-204 properties of, 70 204t Polysulfone ultrafiltration hollow-fiber membrane, 76 4 Polyfsulfonic acid)s, 23 717-725 biomedical applications of, 23 722-723 uses for, 23 717... 

O. Miyawaki, K. Nakamura, and T. Yano, Experimental investigation of continuous NAD recycling by conjugated enzymes immobilized in ultrafiltration hollow fiber, J. Chem. Eng. Jpn., 15(3), 224-228 (1982). 

Ultrafiltration hollow-fiber modules are usually made with a shell and tube configuration. The fibers are potted at both ends of the module with the fiber lumen open for recirculation of the process stream (Figure 21). Naturally, strainers or prefilters must be utilized to eliminate plugging of the fibers. At Nude-pore, it has been shown that larger diameter hollow fibers, 1.5 to 3mm in i.d., are much less prone to fouling. Fortunately, all UF hollow fiber systems can be back-washed and are amenable to a number of cleaning techniques. 

The substrate specificity of the amino acylase from Aspergillus oryzae is very broad, and a wide range of proteinogenic and non-proteinogenic N-acetyl and N-chloroacetyl amino acids are transformed in the presence of the L-amino acylase. The enzyme membrane reactor (Fig. 5) is operated continuously as a loop reactor, and the enzyme is retained by an ultrafiltration hollow-fiber membrane (molecular weight cut off 10000 Dalton). 

Based on a commercial polyethersulfone ultrafiltration hollow fiber membrane, a SPEEK-coated composite membrane was tested for the separation of As(V) from drinking water sources. The characteristics of the support membrane and the composite membrane are listed in Table 11.3. The membrane has typical properties (dimensions, water permeability, pore size etc.) of a UF... 

Table 11.3. Characteristics of PES ultrafiltration hollow fiber membrane.

Figure 11.4. SEM photos of polyethersulfone ultrafiltration hollow fiber membrane. The membrane shows a sponge-like morphology with very open interior structure and a rather thin skin layer (Song etal,im).

Amphiphilic Pluronic triblock copolymers of two blocks of poly-(ethylene oxide) (PEO) and poly(propylene oxide) in between have worth as both the surface modifier and pore former in the fabrication of membranes (77). The effect of Pluronics with different molecular architectures and contents as a pore forming additive for the fabrication of poly(ethersulfone) ultrafiltration hollow fibers has been investigated. 

Ultrafiltration hollow fiber Laminar / turbulent Core-side fluid and gel layer Sh = 1.86fReSc- l PDF or ODF... 

Wang, K. Y., Matsuura, T., Chung, T. S., and Guo, W. R. (2004h). The effects of flow angle and shear rate within the spinneret on the separation performance of poly(ethersulfone) (PES) ultrafiltration hollow fiber membranes. J. Membr. Sci. 240, 67. 

M. Khayet, C.Y. Feng, K.C. Khulbe, and T. Matsuura. (2002). Study on the effect of a non-solvent additive on the morphology and performance of ultrafiltration hollow-fiber membranes, Desalination 148 321-327. 

Fig. 23. Two types of hollow-fiber modules used for gas separation, reverse osmosis, and ultrafiltration applications, (a) Shell-side feed modules are generally used for high pressure appHcations up to - 7 MPa (1000 psig). Fouling on the feed side of the membrane can be a problem with this design, and pretreatment of the feed stream to remove particulates is required, (b) Bore-side feed modules are generally used for medium pressure feed streams up to - 1 MPa (150 psig), where good flow control to minimise fouling and concentration polarization on the feed side of the membrane is desired.

Nonselective membranes can assist enantioselective processes, providing essential nonchiral separation characteristics and thus making a chiral separation based on enantioselectivity outside the membrane technically and economically feasible. For this purpose several configurations can be applied (i) liquid-liquid extraction based on hollow-fiber membrane fractionation (ii) liquid- membrane fractionation and (iii) micellar-enhanced ultrafiltration (MEUF). 

The polyethersulfone capillary ultrafiltration membranes (Daicel Chemical Industries, Ltd., inner diameter 0.8 mm, outer diameter 1.3 mm, length 40 cm, molecular weight cutoff 150 000, water permeability 3 x 10 m m s kPa at 298 K) were used. The length and area of membrane consisting of seven hollow fibers are 40 cm and 70 cm. ... 

Nonbiological methods for removal of trichloroethylene from water are also being studied. These include the use of a hollow fiber membrane contactor (Dr. A.K. Zander, Clarkson University), photocatalysis by solar or artificially irradiated semiconductor powders (Dr. G. Cooper, Photo-catalytics, Inc.), and micellar-enhanced ultrafiltration (Dr. B.L. Roberts, Surfactant Associates, Inc.). 

An example of an industrial membrane bioreactor is the hollow-fiber membrane system for the production of (-)-MPGM (3-(4-methoxyphenyl)glycidic acid methyl ester), which is an important intermediate for the production of diltiazem hydrochloride [81, 82]. For the enantiospecific hydrolysis of MPGM a hollow-fiber ultrafiltration membrane with immobilized lipase from Serratia marcescens is used. (-f)-MPGM is selectively converted into (2S,3J )-(-F)-3-(4-methoxyphenyl)glyci-dic acid and methanol. The reactant is dissolved in toluene, whereas the hydrophilic product is removed via the aqueous phase at the permeate side of the membrane, see Fig. 13.9. EnantiomericaUy pure (-)-MPGM is obtained from the to-... 

Removing Small Molecular Weight Contaminants. Ultrafiltration in hollow fiber membrane cartridges was the best method found to remove small molecular weight materials (75). It also served to concentrate the enzymes and change the buffer (via diafiltration) to that required for the next purification step. A 10,000 mwt... 

Membrane extraction offers attractive alternatives to conventional solvent extraction through the use of dialysis or ultrafiltration procedures (41). The choice of the right membrane depends on a number of parameters such as tlie degree of retention of the analyte, flow rate, some environmental characteristics, and tlie analyte recovery. Many early methods used flat, supported membranes, but recent membrane technology has focused on the use of hollow fibers (42-45). Although most membranes are made of inert polymers, undesired adsorption of analytes onto the membrane surface may be observed, especially in dilute solutions and when certain buffer systems are applied. 

Polymer-Assisted Ultrafiltration of Boric Acid. The Quickstand (AGT, Needham, MA) filtration apparatus is pictured schematically in Figure 3. The hollow fiber membrane module contained approximately 30 fibers with 0.5 mm internal diameter and had a nominal molecular weight cut-off of 10,000 and a surface area of 0.015 m2. A pinch clamp in the retentate recycle line was used to supply back pressure to the system. In a typical run, the transmembrane pressure was maintained at 25 psig and the retentate and permeate flow rates were 25 ml/min and 3 ml/min, respectively. Permeate flux remained constant throughout the experiments. 

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 a polysulfone coating applied to a hollow-fiber support. The PRISM (Monsanto) gas-separation system based on this concept has been a significant breakthrough in gas-separation... 

ULTRAFILTRATION. Ultrafiltration is a pressure-driven filtration separation occurring on a molecular scale. See also Dialysis Filtration Hollow-Fiber Membranes Membrane Separations Technology and Reverse Osmosis. Typically, a liquid including small dissolved molecules is forced through a porous membrane. Large dissolved molecules, colloids, and suspended solids that cannot pass through the pores are retained,... 

A large number of fibers are ait to length, and potted in epoxy resin at each end, The fiber bundle is shrouded in a cylinder which aids in permeate collection, reduces airborne contamination, and allows back pressing of the membrane Hollow-fiber membranes have also found use in ultrafiltration. 

In natural systems therefore part of the complexation capacity might be caused by colloidal material. This was demonstrated in experiments on the complexation capacity of samples from the Scheldt estuary at different salinities, determined as function of several concentration steps, using a hollow fiber ultrafiltration set up with a theoretical cut off of MW 5000 (Kramer and Duinker, 1984a). 

The types of hollow fiber membranes in production are illustrated in Figure 3.32. Fibers of 50- to 200-p.m diameter are usually called hollow fine fibers. Such fibers can withstand very high hydrostatic pressures applied from the outside, so they are used in reverse osmosis or high-pressure gas separation applications in which the applied pressure can be 1000 psig or more. The feed fluid is applied to the outside (shell side) of the fibers, and the permeate is removed down the fiber bore. When the fiber diameter is greater than 200-500 xm, the feed fluid is commonly applied to the inside bore of the fiber, and the permeate is removed from the outer shell. This technique is used for low-pressure gas separations and for applications such as hemodialysis or ultrafiltration. Fibers with a diameter greater than 500 xm are called capillary fibers. 

The second type of hollow fiber module is the bore-side feed type illustrated in Figure 3.46(b). The fibers in this type of unit are open at both ends, and the feed fluid is circulated through the bore of the fibers. To minimize pressure drop inside the fibers, the diameters are usually larger than those of the fine fibers used in the shell-side feed system and are generally made by solution spinning. These so-called capillary fibers are used in ultrafiltration, pervaporation, and some low-to medium-pressure gas applications. Feed pressures are usually limited to below 150 psig in this type of module. 

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