Studied with hollow-fiber membrane

Americium, in nitric acid waste, 182 Americium transfer behavior cation exchange of strip solution, 186 effect of feed-to-strip ratio, 186 effect of nitric acid, 185 studied with hollow-fiber membrane, 183 Analytical models, to predict facilitation factors, 12... 

Procedures. Americium transfer behavior was studied using hollow fiber membrane modules assembled In the laboratory. Each module consisted of two Armak Accurel hollow fibers, each 11.5 cm long and 0.15 cm l.d. with a 0.1 cm wall thickness, sealed Into a glass tube 14 cm long x 0.8 cm l.d. by using RTV silicone adhesive. The hollow fibers have a nominal void volume of 75Z. The glass tube Is equipped with side Inlet and outlet ports. 

Demetriou et al. [25] described a capillary hollow fiber membrane based bioreactor in which microcarrier-attached hepatocytes are placed in the extracapillary space on the exterior surface of the capillary hollow fiber membranes as shown in Fig. 1. Recent experimental studies with this device have demonstrated its efficacy in animal models. By using cryopreserved microcarrier-attached hepatocytes this system offers the convenience of being readily available when needed. 

In the present work, continuous extraction of lactic acid from an aqueous solution with a solvent consisting of Alamine 336 and 2-octanol in a hollow-fiber membrane extractor was studied. The lactic acid in the solvent... 

On the contrary, silica membranes with pore diameters in the 0.3-0.8 nm on porous glass supports have been claimed to exhibit an H2/CO separation factor as high as 30. This is significantly higher than what Knudsen diffusion alone predicts. It is possible that some molecular sieving takes place in the reportedly small pores in the silica membranes. This postulation appears to be further reinforced by another study using hollow fiber silica... 

Chen and Lee [24] studied lactic acid production from dilute acid pretreated a-cellulose and switchgrass by L. delbruckii NRRL-B445 in the presence of a fungal cellulase in a fermentor extractor employing a microporous hollow fiber membrane (MHF). This reactor system was operated in a fed-batch mode with continuous removal of lactic acid by in situ extraction. A tertiary amine (alamine... 

Experimental. The hollow fiber membranes used for this study were Naflon 811, which Is a copolymer of polysulfonyl fluoride vinyl ether and polytetrafiuoroethylene, and sulfonated and/or quaternated derivatives of polyethylene (kindly supplied by Dr. E. Korngold from Ben Gurlon University In Israel). The aqueous alcohol solutions studied thus far are those of methanol, ethanol and 2-propanol. The separations were accomplished via the pervaporatlon process as described In Reference 9. Counter Ions were replaced In the hollow fiber by soaking the permeator for twenty four hours In 1 molar solutions of the pertinent Ions. For example, experiments were conducted with Na as a counter Ion. When this set of experiments was finished, the sodium was exchanged by Ll etc. Each data point shown In Figure 14 consists of 6 to 10 measurements taken over a time period of 8 hours. Re-runs with the various counter Ions proved that the intrinsic properties of the membrane remain unchanged and the permeability measurements are reproducible. 

Steady state models of membrane bioreactors utilizing a multi-enzyme system, which in addition to the main reaction promotes the simultaneous regeneration of the co-factor (for further discussion see Chapter 4) have been developed by different groups in Japan [5.109, 5.110]. Several of these studies have also considered the effect of backmixing [5.111, 5.112]. A model of an enzymatic hollow fiber membrane bioreactor with a single enzyme, which utilizes two different substrates (reaction 5.42) has been developed recently by Salzman et al [5.113]. 

We have developed a one-dimensional non-isothermal model for the countercurrent WGS membrane reactor with a C02-selective membrane in the hollow-fiber configuration using air as the sweep gas. Figure 1 shows the schematic of each hollow-fiber membrane with catalyst particles in the reactor. The modeling study of the membrane reactor is based on (1) the CO2 / H2 selectivity and CO2 permeance reported by Ho [1, 2] and (2) low-temperature WGS reaction kinetics for the commercial catalyst copper oxide, zinc oxide, aluminum oxide (CuO/ZnO/ AI2O3) reported by Moe [3] and others [4]. In this modeling study, the model that we have developed has taken into account critical system parameters including temperature, pressure, feed gas flow rate, sweep gas (air) flow rate, CO2 permeance, CO2 /H2 selectivity, CO concentration, CO conversion, H2 purity, H2 recovery, CO2 concentration, membrane area, water (H20)/C0 ratio, and reaction equilibrium. 

Olefins. Facilitated transport of olefins has also been reported in the literature. LeBlanc et al. (2 ) studied ethylene transport using a silver Ion carrier in an Ion exchange membrane. Hughes et al. (23) presented the results of a bench and pilot scale study of ethylene and propylene transport using a silver ion Immobilized In anisotropic, porous hollow fiber membranes. This work is very significant because it is the first report facilitated transport membranes used on a commercial scale. Teremoto et al. (24) also studied ethylene transport with a silver ion carrier in a supported liquid membrane. They found a selectivity for ethylene over ethane of approximately 1000 when the silver nitrate concentration was 4 mol/ dm. ... 

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... 

A number of studies have been carried out to evaluate the effect of injection of air into the lumen of tubular and hollow fiber membranes on the performance of membrane filtration. Figure 10.38 shows the filtration results obtained by Cui et al. [85] using a vertically installed tubular membrane module (12.7 mm i.d., PVDF, MWCO, 100 kDa) with dextran solution... 

The membrane model in the implemented ACM module was first validated with the experimental results of Pan (1986). In the experiments, the effect of varying stage cut (that is, the fraction of feed that permeates through the membrane) on mole fraction of H2 in the permeate was studied using asymmetric hollow fiber membranes in co- and counter-current configurations. Parameters of the membrane module can be found in Table lO.A.l stage cut varies from 0.34 to 0.55 in the counter-current configuration and from 0.35 to 0.6 in the... 

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