Membrane bags

Eig. 20. Cut view of Chlorine Engineers membrane bag cell a, manifold b, frame c, partition plate d, sealing plug e, recirculated NaOH inlet f, cathode g, anode h, cathode can i, membrane bag j, base k, butterfly valve 1, feed brine m, depleted brine n, caustic outlet. 

FIGURE 5A.2 A dialysis experiment. The solution of macromolecules to be dialyzed is placed in a semipermeable membrane bag, and the bag is immersed in a bathing solution. A magnetic stirrer gently mixes the solution to facilitate equilibrium of diffusible solutes between the dialysate and the solution contained in the bag. 

Preliminary Purification of Dandelion and Sweet Corn. The plant extract in pH 7 buffer was sealed in a Visldng cellulose dialysis membrane bag, immersed in a volume of aqueous pH 7 buffer equal to twice the volume of its contents, and shaken for at least 2 hours. The outside solution was replaced, and die entire operation repeated twice. The three outside buffer solutions were combined. A dialysis blank was prepared in similar fashion. The dialyzate was washed once with ethyl acetate. The aqueous phase was adjusted to pH 2 with sulfuric acid and extracted several times with ethyl acetate. The combined ethyl acetate extracts were evaporated to dryness, and redissolved in a small volume of methanol. 

A modified extraction cell containing a bag-shaped membrane made of LDPE, instead of an FS membrane, was designed to contain the extraction solvent for the extraction of polycyclic musk compounds and pharmaceuticals in wastewater.60 The extraction cell was further developed in terms of membrane design and material. A dense nonporous PP membrane was preferably chosen as a membrane bag in the extraction cell, which was incorporated into a fully automated MASI device that is now commercially available from Gerstel (MUlheim an der Ruhr, Germany). 

FIGURE 15.8 Release of FITC-dextran from membrane bags prepared from 50 wt% PAA grafted PVDF membranes into dissolution medium at pH 2.0 (filled circles) and pH 7.0 (open circles). (From Jarvinen, K., Akerman, S., Svarfvar, B., Tarvainen, T., Viinikka, P., and Paronen, P., Pharm. Res., 15, 802, 1998. With permission.)... 

Jarvinen K, Akerman S, Svarfvar B, Tarvainen T, Viinikka P, and Paronen P. Drug release from pH and ionic strength responsive poly(acrylic acid) grafted poly(vinylidenefluoride) membrane bags in vitro. Pharm. Res. 1998 15(5) 802-805. 

A 20 ml headspace vial was filled with 15 ml of the aqueous sample. A membrane bag (4 cm long with a wall 198... 

The chapter by Krull et al (59) use membranes in vesicle form ("membrane bags"). Fluorophore-labeled receptors are incorporated into the vesicles which, drawing upon known receptor binding chemistry, exhibit alterations in fluorescence intensity in the presence of the agonist carbamylchollne. This project aims at incorporating this scheme into membranes on the surfaces of optical fibers. 

Another interesting application of membranes is shown in the work of JSrvinen and coworkers [13] who study drug release from pH and ionic strength responsive PAA grafted PVDF membrane bags in vitro. Square-shaped bags... 

The simplest approach is based on catalyst trapping within a nanoporous membrane bag. It provides adequate dispersion of the catalyst and guarantees minimal interaction between the catalyst and the polymer, thus allowing the use of... 

As stated previously, the dendrimer catalysts had been developed with the purpose of catalyst recycling based on dialysis, using membrane bags fabricated from a commercially available dialysis membrane (Sigma-Aldrich benzoylated dialysis tubing, MWCO 2000). The general principle and its practical implementation are depicted in Figure 19.7. 

The transport of the substrates and the product in and out of the membrane bag occurred by diffusion, which was accelerated by operating at an elevated temperature of 40 °C, consequently resulting in somewhat lower enantioselectivity. The substrates migrated into the membrane bag, where they interacted with the catalytically active terminal groups of the dendrimer and were converted to the product. Consequently, the latter was enriched in the interior and then passed through the membrane to the exterior part of the reactor following the concentration gradient. 

Figure 19 Series showing the course of one recycling (a) dendrimer-filled membrane bag in the yellow solution of the substrates (b) colorless solution after complete conversion (c) transfer of the bag into another vial and (d) subsequent reaction cycle [28].

This reduced volume v is scaled so that a sphere is characterized by unity, the maximal possible volume-to-area ratio for a geometrical object. Deflated vesicles have values smaller than one, and zero would correspond to an empty membrane bag without any aqueous content. The reduced volume v represents a convenient... 

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