Dialysis reactor

Hollow fiber reactors [7] and dialysis reactors [8] avoid shear stress by separating cells and flowing media. In both reactors nutrient supply takes place by diffusion through the capillary wall or the dialysis membrane. 

A scale-up of the dialysis reactor system for suspended cells is feasible by application of external dialysis modules, which are coupled between a culture vessel and a dialysis vessel (Fig. 3). The culture broth and dialysis medium are pumped in an external loop through the dialysis module. 

The influence of the OTR on kinetics (and therefore on productivity) was indicated in Equs. 5.169 and 5.170. Therefore, we will discuss here primarily those process engineering factors involved in various different types of reactors and operations. Last but not least, some unconventional reactors such as membrane (dialysis) reactors and synchronous culture techniques will be discussed. 

In open fibers the fiber wall may be a permselective membrane, and uses include dialysis, ultrafiltration, reverse osmosis, Dorman exchange (dialysis), osmotic pumping, pervaporation, gaseous separation, and stream filtration. Alternatively, the fiber wall may act as a catalytic reactor and immobilization of catalyst and enzyme in the wall entity may occur. Loaded fibers are used as sorbents, and in ion exchange and controlled release. Special uses of hoUow fibers include tissue-culture growth, heat exchangers, and others. 

Figure 2.5 Possible technological solutions to bioprocess problems a) Fed-batch culture b) Continuous product removal (eg dialysis, vacuum fermentation, solvent extraction, ion exchange etc) c) Two-phase system combined with extractive fermentation (liquid-impelled loop reactor) d) Continuous culture, internal multi-stage reactor e) Continuous culture, dual-stream multi-stage reactor f) Continuous culture with biomass feedback (cell recycling). (See text for further details).

Surface-modified electrodes were used for prevention of high overpotentials with direct oxidation or reduction of the cofactor, electrode fouling, and dimerization of the cofactor [7cj. Membrane electrochemical reactors were designed. The regeneration of the cofactor NADH was ensured electrochemically, using a rhodium complex as electrochemical mediator. A semipermeable membrane (dialysis or ultrafiltration) was integrated in the filter-press electrochemical reactor to confine... 

Figure 5 Five-channel enzyme sensor for the simultaneous determination of glucose, lactate, glutamate, glutamine, and ammonium. MFM, microfiltration module WV, valves P, pumps DC, dialysis cell B, blank reactors MC, reactor D, biosensor flow cell. (Adapted with permission from Ref. 34.)...

The same hyperbranched polyglycerol modified with hydrophobic palmitoyl groups was used for a noncovalent encapsulation of hydrophilic platinum Pincer [77]. In a double Michael addition of ethyl cyanoacetate with methyl vinyl ketone, these polymer supports indicated high conversion (81 to 59%) at room temperature in dichloromethane as a solvent. The activity was stiU lower compared with the noncomplexed Pt catalyst. Product catalyst separation was performed by dialysis allowing the recovery of 97% of catalytic material. This is therefore an illustrative example for the possible apphcation of such a polymer/catalyst system in continuous membrane reactors. 

Fig. 3 Schematic representation of batch-wise passive membrane dialysis (A) and continuous membrane filtration dead-end-filtration (B) and loop reactor (C)...

Analytical column and post column immobilized enzyme reactor supplied as part of a ACh/Ch assay kit. Sodium phosphate buffer pH 8.5 containing Kathon CG (Rohm and Haas, PA, USA), [1 mL/min]. Electrochemical at + 0.5 V versus Ag/AgCl. Human plasma and peritoneal dialysis effluent. [185]... 

Extracorporeal dialysis can be implemented for blood decontamination. Enzymes can be immobilized on dialysis cartridges (Klein and Langer, 1986). In that case, kcJKm has to be as high as possible and the flow rate reduced to increase the efficiency of the reactor. Moreover, accessibility of OP molecules to the enzyme active center must not be altered by the immobilization method or by matrix effects. The enzyme concentration per surface unit has to be maximized to reduce diffusion constraints. First order... 

Also, dialysis was reported to remove TMCs from reaction mixtures. No mechanical pressure is needed here, clearly facilitating the mechanical and safety requirements. The first proof of concept was given with Ru-BINAP confined in a PDMS- envelop simply submerged in the reactor. In a catalytic transfer hydrogenation, the PDMS-membrane retained the catalyst... 

Chrome azurol S was used to determine A1 in tap water, dialysis fluids and alkali metal salts [1] and in mine well water [2]. The preliminary preconcentration of the eomplex on a polyethylene powder was applied [1]. Aluminium species (Al(III) ions and Ali304(0H)24 (H20)i2 ) in aqueous soil extracts and humic waters were determined by FIA method using Chrome azurol S after preliminary retaining of the analyte on a column reactor containing 8-quinolinol immobilized onto Fractogel and selective elution with different elluents [3]. 

Mediator-chemically modified electrodes have been coupled either with ADH membranes to give enzyme electrodes (Cenas et al. 1984) or with ADH reactors, e.g., in an FIA device (Huck et al. 1984). Quinoidic groups, Meldola s Blue, and Nile Blue have been used as mediators. Albery et al. (1987b) employed an electrode containing NMP+ and TCNQ" in a PVC carrier for NADH oxidation. ADH was entrapped on the sensor surface by a dialysis membrane. 

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