Polyacrylamides, adsorption onto

A recent paper by Lairdinvestigated the efficacy of HPAM flocculation of kaolinite, illite and quartz by carrying out visible absorption experiments. He concluded that HPAM more effectively flocculates kaolinite than quartz or illite. This was also the conclusion of previous work by Allen et al. who studied the adsorption of HPAM onto kaolinite, quartz and feldspar at various HPAM concentrations and solution pH by X-ray photoelectron spectroscopy (XPS). Much of the previous work on polyacrylamide adsorption onto aluminosilicates monitored the adsorbed amount by viscometry, carbon analysis and radiotracer techniques. These methods rely on following adsorption by subtraction from that detected in solution. 

Four methods have been developed for enzyme immobilization (1) physical adsorption onto an inert, insoluble, solid support such as a polymer (2) chemical covalent attachment to an insoluble polymeric support (3) encapsulation within a membranous microsphere such as a liposome and (4) entrapment within a gel matrix. The choice of immobilization method is dependent on several factors, including the enzyme used, the process to be carried out, and the reaction conditions. In this experiment, an enzyme, horseradish peroxidase (donor H202 oxidoreductase EC 1.11.1.7), will be imprisoned within a polyacrylamide gel matrix. This method of entrapment has been chosen because it is rapid, inexpensive, and allows kinetic characterization of the immobilized enzyme. Immobilized peroxidase catalyzes a reaction that has commercial potential and interest, the reductive cleavage of hydrogen peroxide, H202, by an electron donor, AH2 ... 

A feature of the neutron reflectivity study on polyDMDAAC and surfactant adsorption by Penfold et al. [74] was that the adsorbed layer of polyDMDAAC was remarkably robust and unaffected by the subsequent surfactant adsorption. This is not always the case, and Fielden et al. [76] reported a large increase in the thickness of the surface layer of AM-MAPTC on mica due to complex formation with SDS. Thickness increases with electrolyte and pH were reported for high molecular weight polyacrylamide adsorbed onto silica, measured by null ellip-sometry by Samoshina et al. [82] in the absence of surfactant. Complex formation at the interface, resulting in layer thickening, was also reported by Dedinaite et al. [83] for PCMA/SDS mixtures on mica from AFM measurements. 

The commonly recognized adjuvants are remarkable for their diversities. Soluble immunogens can be adsorbed onto the following kinds of inorganic suspensions alumina cream, aluminum phosphate, and aluminum sulfate. Adsorption onto organic carriers such as blood, charcoal, calcium alginate, or polyacrylamide gels has also enhanced responses. A Maalox... 

Chibowski, S., Effect of functional groups of polyacrylamide and polyacryhc acid on their adsorption onto TiOj surface, J. Colloid Interf. Sci., 140, 444, 1990. 

With polyacrylamide adsorbed onto modified glass beads, a "hydrodynamic Isotherm" (variation of the thickness with the bulk concentration) could not be obtained through measurements of the suspension viscosity, since at low bulk concentration, adsorption Induces bead aggregation ( ). Table I presents the plateau values of for different samples, and they consistently overestimate the radius of gyration value by about 70 It Is therefore clear that, because of strong lateral excluded volume Interactions, the chain loops are stretched away from the surface. Moreover, Table I also shows that the ratio between the mean monomer density at the surface and in solution (Inside the coll) veurles between 20 and 30. Thus, despite the excluded volume Interactions, one observes that the... 

Entrapment in polyacrylamide gel over a platinum grid matrix Glutaraldehyde-mediated reaction with a nylon-polyethyleneimine copolymer Reaction with macroporous aminated silo chrome coated with an acrolein-vinylpyridine copolymer Adsorption onto tannin coupled to amino hex y 1-cellulo se Entrapment in cellulose fibres Carbodi-imide-mediated reaction with chitosan... 

Entrapment in polyacrylamide gel caibodi-imide-mediated coupling to aminohexyl-agarose or to derivatized nylon nets adsorption onto diethyl-aminoethyl-dextran Glutaraldehyde-mediated reaction with aminoethyl-cellulose... 

Cyclodextrin D-Glucanotransferases.—The neutral cyclodextrin D-glucano-transferase from an alkaliphilic Bacillus species has been purified by adsorption onto starch, ion-exchange chromatography, gel filtration, and polyacrylamide gel electrophoresis. The enzyme (mol. wt. 8.5—8.8 x 10 in the presence of sodium dodecyl sulphate) is most active at pH 7 and 50 °C, is thermally stable, and converts starches and glycogens principally into cyclohepta-amylose. 

Zhang, X., Zheng, S., Lin, Z., Zhang, J., 2012a. Removal of basic fuchsin dye hy adsorption onto polyacrylamide/Laponite nanocomposite hydrogels. Synthesis and Reactivity in Inorganic Metal 42, 1273—1277. 

In the case of macroions the relationship between relative mobiUties and charge is complicated by the possibility that selective retardation of the ions occurs as a result of physical impedence by the gel matrix and adsorption onto the stationary polyacrylamide. Contributions from both occur with all ions, but for proteins the adsorption is less important than the filtering. At the simplest level this filtering would be described through frictional coefficients [Eq. (6)], which for a fixed pore size increase in proportion to the cube root of the mass. Thus, the velocity is proportional to and the relative position of macroions on... 

Mineral segregation in industry relies heavily on the selective adsorption of macromolecules onto the surfaces of those minerals that have particular industrial applications. This selectivity is governed mainly by the surface chemistry of the mineral and the type of polymer used as a flocculant. " Effectiveness of flocculation depends upon the charge, concentration and molecular weight of the polymer, and also the pH and salt concentration of the clay suspension. The bonding between the anionic flocculant polyacrylamide (PAM) and clay mineral surfaces has been effectively reviewed recently by Hocking et al and the reader is referred to this should they require an in-depth literature review. For more information on general colloidal chemistry of clay suspensions the reader is referred to the review of Luckham and Rossi." ... 

A related, but alternative, approach uses layer-by-layer adsorption driven by hydrogen-bonding interactions [51]. This has been accomplished with polyvinylpyrrohdone, polyvinyl alcohol, polyacrylamide, and polyethylene oxide. In the case of polyaniline, comparisons with films assembled via the electrostatic mechanism, using sulphonated polystyrene, indicate that the nonionic polymers adsorb onto polyanihne with a greater density of loops and tails and form highly interpenetrated bilayers with high polyaniline content. 

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