Permeable membrane dialysis

Meadows, J.C. Tillitt, D.E. Schwartz, T.R. Schroeder, D.J. Echols, K.R. Gale, R.W. Powell, D.C. Bursian, S.J. 1996, Organochlorine contaminants in double-crested cormorants from Green Bay, Wisconsin 1. Large-scale extraction and isolation from eggs using semi-permeable membrane dialysis. Arch. Environ. Con. Tox. 31 218-224. 

Fig. 35. Schematic diagram of a plate-and-frame electro dialysis stack. Alternating cation- and anion-permeable membranes are arranged in a stack of up to...

Electrodialysis. In reverse osmosis pressure achieves the mass transfer. In electro dialysis (qv), dc is appHed to a series of alternating cationic and anionic membranes. Anions pass through the anion-permeable membranes but are prevented from migrating by the cationic permeable membranes. Only ionic species are separated by this method, whereas reverse osmosis can deal with nonionic species. The advantages and disadvantages of reverse osmosis are shared by electro dialysis. 

An easy, rapid and environmentally friendly methodology was developed for the extraetion of pyrethroid inseetieide residues from semi permeable membrane deviees (SPMD), based in a mierowave-assisted extraetion, in front of a dialysis method nowadays widely employed. Several solvent sueh as hexane, toluene, aeetonitrile, eyelohexane and ethyl aeetate were tested as mierowave-assisted extraetion solvent. Mixtures of hexane and toluene with aeetone were also assayed and provide better results than single solvents. 

While it would be difficult to enumerate all of the efforts in the area of implants where plastics are involved, some of the significant ones are (1) the implanted pacemaker, (2) the surgical prosthesis devices to replace lost limbs, (3) the use of plastic tubing to support damaged blood vessels, and (4) the work with the portable artificial kidney. The kidney application illustrates an area where more than the mechanical characteristics of the plastics are used. The kidney machine consists of large areas of a semi-permeable membrane, a cellulosic material in some machines, where the kidney toxins are removed from the body fluids by dialysis based on the semi-permeable characteristics of the plastic membrane. A number of other plastics are continually under study for use in this area, but the basic unit is a device to circulate the body fluid through the dialysis device to separate toxic substances from the blood. The mechanical aspects of the problem are minor but do involve supports for the large amount of membrane required. 

The technique consists of a microdialysis probe, a thin hollow tube made of a semi-permeable membrane usually around 200-500 /xm in diameter, which is implanted into the skin and perfused with a receiver solution that recovers the unbound permeant from the local area. In principle, the driving force of dialysis is the concentration gradient existing between two compartments separated by a semi-permeable membrane. For skin under in vivo conditions, these compartments represent the dermal or subcutaneous extracellular fluid (depending on the probe position) and an artificial physiological solution inside the probe [36-38],... 

BDE 17, 28, 47, 66, 85, 99, 100, 153, 154 183 Palm oil Palm oil Extraction by dialysis in hexane using a semi-permeable membrane. Purification thorugh multilayer column filled with neutral silica, silica modified with sulfuric acid (44%, w/w), and silica modified with KOH. Gas Chromatography (VF-5MS Factor Four, Varian) IT-MS 0.07-1.3 pg (instrumental limit of detection) [42]... 

Dialysis may be described as the fractional diffusion of solids from one side of a semi-permeable membrane to the other side under a concentration gradient Electrolysis is die process of local or spatial separation of the ions of an electrolyte and the transfer of their respective charges, ie the decompn of a compd by an elec current... 

Amarita et al. [48] Lactose Milk Lactases (Lactozym and / -galactosidase of Enterobacter agglomerans) adsorbed onto diethylaminoethyl cellulose (DE-52), and confined between the surface of a gas-permeable membrane of a C02 electrode and a dialysis membrane C02 potentiometric electrode ... 

Capannesi et al. [78] Polyphenols Olive oil Tyrosinase/with glutaraldehyde onto a preactivated membrane (Immobilon) sandwiched between the gas permeable membrane of the electrode and a dialysis membrane Amperometric oxygen probe... 

Cut out a disk of about 5-8 mm in diameter and about 1mm in thickness of the agarized gel stratified on the Petri dish, remove from it and sandwich between a dialysis membrane and the gas permeable membrane of the Clark electrode secure the whole assembly to the head of the electrode by means of an O-ring. 

In dialysis, the latex is confined with a semi-permeable membrane (e.g., in a dialysis bag), and the aqueous phase ions are removed by diffusion across this semi-permeable membrane. 

Proteins can be separated from small molecules by dialysis through a semi-permeable membrane which has pores that allow small molecules to pass through but not proteins. 

Proteins can be separated from small molecules by dialysis through a semi-permeable membrane such as cellophane (cellulose acetate). Pores in the membrane allow molecules up to approximately 10 kDa to pass through, whereas larger molecules are retained inside the dialysis bag (Fig. 1). As most proteins have molecular masses greater than 10 kDa, this technique is not suitable for fractionating proteins, but is often used to remove small molecules such... 

Equilibrium dialysis is used in a number of examples to analyse the ratio of lipid-bound to free analyte. Kramer et al. (1998) described the use of equilibrium dialysis by separating the liposome suspension and the water phase by a semi-permeable membrane. The analyte is dissolved in the water compartment of the system and diffuses into the liposome compartment. If equilibrium is reached, the remaining concentration of the analyte in the water compartment is determined by means of a quantification method (mainly HPLC or LCMS, fluorescence techniques) and the partition coefficient is calculated. Kramer et al. (1997) used a radio tracer substance as analyte to quantify the compound in both compartments using liquid scintillation counting. 

Electrodialysis — Figure. The electro dialysis cell (a) [i] (a = anion-permeable membrane c = cation-permeable membrane o = positive ion = negative ion ion migration under action of electrical current (b), causes salt depletion in alternate compartments and salt enrichment in adjacent ones (c))... 

Hollow membrane fibers are required for many medical application, e.g. for disposable dialysis. Such fibers are made by usmg an appropriate fiber spinning technique with a special inlet in the center of the spinneret through which the fiber core forming medium (liquid or gas) is injected. The membrane material may be made by melt-spinning, chemical activated spinning or phase separation. The thin wall (15-500 xm thickness) acts as a semi-permeable membrane. Commonly, such fibers are made of cellulose-based membrane materials such as cellulose nitrate, or polyacrylonitrile, polymethylmethacrylate, polyamide and polypropylene (van Stone, 1985). 

Equilibrium Dialysis Method. The equilibrium dialysis method is based on the diffusion of the volatile compound through a semi-permeable membrane placed between two compartments containing the model wine and macromolecules (11). In the experiment, ImL solution of macromolecule in the model wine was placed on one side of the membrane (compartment 1) and 1 mL of the model wine containing a known amount of the volatile compound on the other side (compartment 2). The system was shaken at 30 °C for 12 h to reach equilibrium of the free ligand (volatile compound) between the two compartments of the cell. At equilibrium, the concentration of the volatile compound was determined by gas chromatography. The difference in concentration of the volatile compound between the two compartments represents the amount of the volatile compound bound to the macromolecule. 

Polyelectrolyte complexes are very promising materials for preparing semi-permeable membranes of definite permeability and selectivity The methods of preparation and the properties of membranes made of polyelectrolyte complexes based on strong polyelectrolytes, e.g. poly(sodium sterene sulfonate) and poly(vinylbenzyl-trimethyl ammonium chloride) were described These membranes may be applied for reverse osmosis in the desalting of sea-water, for dialysis and ultrafiltration in purifications and concentration of water solutions containing coUoids or micro-and macroparticles ... 

Figure 4.6.5 shows a semi-permeable membrane in a laboratory version of dialysis, a sort of imitation of kidney function. We have a concentrated solution of sugar, say, inside the membrane and the dilute solution, or pure solvent, outside. The two solutions are in contact with each other, and over a period of time, the volume of liquid inside the semi-permeable membrane increases as, overall, solvent moves inside it. It is unlikely that the concentrations will be completely equalised. 

Equihbrium dialysis - Two compartments of a dialysis ceU are divided by a semi-permeable membrane. The protein-hgand complex is aUowed to associate or dissociate across the membrane until equihbrium is attained. By measuring the constituents of the interaction, the binding constant can be obtained from standard formulas. 

Steady-state dialysis - The equihbrium dialysis technique is accelerated by having buffer flow at a constant rate on one side of the semi-permeable membrane and by stirring both sides in order to minimize the concentration gradients [36]. Diafiltration - A type of dialysis equihbrium in which pressure is used to force the ligand-containing solution from one chamber into the protein-containing chamber [37]. 

Meyerhoff and Rechnitz (1976) developed a potentiometric creatinine sensor by inclusion of creatinine iminohydrolase between the gas-permeable membrane of an ammonia electrode and a dialysis membrane. Since the specific activity of the enzyme used was very low, 0.1 U/mg, only 43 mU could be entrapped at the electrode. Therefore the sensor was kinetically controlled and reacted to addition of the enzyme activator tripolyphosphate by an increase in sensitivity from 44 mV to 49 mV per concentration decade and a corresponding decrease of the detection limit. These effects agree with theoretical considerations of reaction-transport coupling. The samples were treated with a cation exchanger to remove endogenous serum ammonia. 

Membrane symmetric microporons with 0.1 to 10 mm pore diameter. Hydraulic permeability 10 to 8 g/s m MPa. Membrane-solnte permeability 0.05 to 9 pm/s, depending on the solute and the membrane. Dialysis transfer coefficient 1 to 10 pm/s. 

---