Cellulose acetate hollow fiber

Fiber Modification. Chemical modification ol the fiber is usually a separate operation. The largest such commercial processing is the deacety lation of cellulose acetate hollow fibers, w hich converts them into regenerated cellulose hollow fibers employed in hemodialysis. 

Tri-acetate Hollow Fibers Polyamide Hollow Fibers Cellulose Acetate Hollow Fibers ... 

Cellulose acetate hollow fiber Coiled hollow fiber module... 

Hughes immobilized AgN03 solutions in cellulose acetate hollow fibers to prepare immobilized liquid membranes for ethylene and propylene transport. 

Figure 12 Diffractogram of dried cellulose acetate hollow fiber membrane.

Separex s,41-43 Grace Membrane Systems cellulose ester,60 Envirogenics GASEP (trademark of Envirogenics Company)64 cellulose triacetate spiral-wound membranes, and Dow cellulose acetate hollow fibers are used to produce a salable product from sour gas streams. 

Several classes of polymeric materials are found to perform adequately for blood processing, including cellulose and cellulose esters, polyamides, polysulfone, and some acrylic and polycarbonate copolymers. However, commercial cellulose, used for the first membranes in the late 1940 s, remains the principal material in which hemodialysis membranes are made. Membranes are obtained by casting or spinning a dope mixture of cellulose dissolved in cuprammonium solution or by deacetylating cellulose acetate hollow fibers [121]. However, polycarbonate-polyether (PC-PE) block copolymers, in which the ratio between hydrophobic PC and hydrophilic PE blocks can be varied to modulate the mechanical properties as well as the diffusivity and permeability of the membrane, compete with cellulose in the hemodialysis market. 

The general process for preparation of the precursors consists of four steps, i.e. dope formation, casting/spinning, dehydration and post-treatment. There are many parameters that will affect the precursor properties during the preparation process. An example for the optimization of spinning condition was reported by He et al., who reported that the optimal conditions for spinning cellulose acetate hollow fiber membranes was found to be as follows bore fluid, water+ NMP (85%) air gap 25 mm bore flow rate, 40% of dope flow rate (2.2 mL min ) and temperature of quench bath, 50... 

Chou, W.L., Yu, D.G. and Yang, M.C. 2005. The preparation and characterization of silverloading cellulose acetate hollow fiber membrane for water treatment Pohm. Adv. 

Phenol Activated carbon-filled cellulose acetate hollow-fiber membranes Pseudomonas putida ATCC 17484 Zhu et al., 2000... 

Zhu, G., Chung, T. S. and Loh, K. C. 2000. Activated carbon-filled cellulose acetate hollow-fiber membrane for cell immobilization and phenol degradation. Journal of Applied Polymer Science, 76,695-707. 

The cellulose acetate hollow fiber for microfiltration has a rougher sulface structure than that for ultrafiltration. The network of the wall is also different. These differences are the result of varying distinctive preparation methods. However, all of these hollow fibers incorporate network structures. 

Table 4. Specification of cellulose acetate hollow fiber...

Adesalinadon experiment with laackish water (1000 ppm NaQ) with cellulose acetate hollow fibers gives a flux of2000 Lmz.day. The intrinsic rejection is 94 % and the mass transfer coefficient is k = 5.4 10 m/s. 

HoUow fibers are widely used for filtration, utilizing the semipermeable nature of their capillary walls. In the medical industry, hollow fiber bioreactors are often made from cellulose and synthetic polymers. Cellulose acetate and cuprammonium rayon are the widely used ceUulose-based hollow fibers, while synthetic hollow fibers are often made from polysulfone, polyamide, and polyacrylonitrile. Modifications can be made to these materials to improve their functions by using polymers based on phospholipid, a substance found in the human cell membrane. 2-methaCTyloyloxyethyl phosphoryl-choline (MPC) is a methacrylate monomer with a phospholipid polar group. When MPC-based copolymers are used as additives for polysulfone, protein adsorption and platelet adhesion can be effectively reduced, thereby improving blood compatibility. Cellulose acetate hollow fiber membranes can also be modified with MPC-based copolymers by means of blending or surface coating to obtain improved permeability. 

Membrane systems to remove acid gas from the natural gas emerged more than three decades ago. Today about half a dozen venders provide membrane systems for natural gas upgrading. Amongst them are UOP (Separex and Grace), who uses cellulose acetate spiral wound module and Natco (Cynara) who uses cellulose acetate hollow fiber membrane modules. Ube, Air Liquide and Air Products offer polyimide hollow fiber membrane modules, and MTR produces perfluoropolymer membranes in spiral wound modules. 

UF 150,000 0.01 Cellulose acetate Hollow fiber Phase separation... 

The hollow-fiber membrane bioreactor took the simple cylindrical geometry housing [dimension 13 mm inner diameter (ID) x 22 mm outer diameter (OD) x 40 mm L see Fig. 14.2]. Cellulose acetate hollow-fiber membranes [200 p,m ID, wall thickness of 14 p,m and molecular weight cutoff (MWCO) of 10 kDa] derived from hemodialysers used to construct the HFMBs. The hollow-fiber membranes were fixed in the bioreactor by using molded silicon rubber. The effective length of the fiber in the reactor was 30 mm with approximately 200 fibers in each bioreactor. The distance between adjacent fibers was approximately 400 p-m, of the order of the distance between natural blood capillaries in human bone. The volume external to the hollow fibers in each HFMB was approximately 3.5 mL, and this volume was available for the collagen gel together with the microcarriers with adherent cells. 

W.L. Chou, M.C. Yang, Effect of take-up speed on physical properties and permeation performance of cellulose acetate hollow fibers. Journal of Membrane Science, 250 (2005) 259-267. 

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