Colloids, adsorption

Haywood and Riley [14] have described a spectrophotometric method for the determination of arsenic in seawater. Adsorption colloid flotation has been employed to separate phosphate and arsenate from seawater [15]. These two anions, in 500 ml filtered seawater, are brought to the surface in less than 5 min, by use of ferric hydroxide (added as 0.1 M FeC 2 ml) as collector, at pH 4, in the presence of sodium dodecyl sulfate [added as 0.05% ethanolic solution (4 ml)] and a stream of nitrogen (15 ml/minutes). The foam is then removed and phosphate and arsenate are determined spectrophotometrically [16]. Recoveries of arsenate and arsenite exceeding 90% were obtained by this procedure. 

Voyce and Zeitlin [487] have used adsorption colloid flotation to determine mercury in seawater. The sample 500 ml is treated with concentrated hy-... 

Ferric hydroxide coprecipitation techniques are lengthy, two days being needed for a complete precipitation. To speed up this analysis, Tzeng and Zeitlin [595] studied the applicability of an intrinsically rapid technique, namely adsorption colloid flotation. This separation procedure uses a surfactant-collector-inert gas system, in which a charged surface-inactive species is adsorbed on a hydrophobic colloid collector of opposite charge. The colloid with the adsorbed species is floated to the surface with a suitable surfactant and inert gas, and the foam layer is removed manually for analysis by a methylene blue spectrometric procedure. The advantages of the method include a rapid separation, simple equipment, and excellent recoveries. Tzeng and Zeitlin [595] used the floation unit that was devised by Kim and Zeitlin [517]. 

Adsorption colloid floation using dodecylamine as surfactant has been used to separate zinc with 95% efficiency from seawater [625]. 

Selenium Adsorption colloid flotation Spectrophotometry of methylene blue complex - [517,546]... 

Johnson, J.E. Matijevic, E. (1992a) Interactions of proteins with uniform colloidal hematite and chromium hydroxide particles. I. Adsorption. Colloid Polymer Sci. 270 353-363... 

The phenomenon of very diluted solutions is well known in radiochemistry. Carrier-free radioactive isotopes could be mentioned as an example. The term denotes a radioisotope of an element in pure form, that is, essentially undiluted, with a stable isotope. The chemical concentration of these radioisotopes is usually very low. For example, 1 kBq radioactivity (applied typically in a tracer experiment) is equivalent to cca. 2 10 12 mol in the case of 137Cs or 90Sr isotopes. In the case of such low concentrations, no chemical system can be considered homogeneous because all surfaces, the wall of the laboratory vessels, or any contaminants in the solution (such as air bubbles, small particles, great molecules, etc.) can initiate interfacial processes and the subsequent formation of heterogeneous phases (adsorption, colloid formation, precipitation, etc.). This is the result of the simple fact that the number of molecules on the surfaces is more than, or at least similar to, the number of particles in the solution. Even in a solution containing... 

Y. S. Kim and H. Zeitlin, The separation of zinc and copper from seawater by adsorption colloid flotation. Separation Science 7(1), 1-12 (1972). 

Lin, Y.-S. Hlady, V. Golander, C.-G., The surface density gradient of grafted poly(ethylene glycol) preparation, characterization and protein adsorption, Colloids Surf. B Biointerfaces 1994, 3, 49-62... 

Thomas, E, Bottero, J.Y., and Cases, J.M., An experimental study of the adsorption mechanisms of aqueous organic acids on porous aluminas. 2. Electrochemical modelling of salicylate adsorption. Colloids Surf., 37, 281, 1989. 

Mackie, A.R., Gunning, A.R, Wilde, R.J., and Morris, V.J. The orogenic displacement of protein from the air/water interface by competitive adsorption, / Colloid Interface Sci., 210, 157, 1999. 

Hirayama, C. Kunitake, M. Formation of the nanotube structure of p-cyclodextrin Au(l]I) surfaces induced by potential controlled adsorption. Colloids Surf., A Phys-icochem. Eng. Asp. 2000. 169, 21-33. 

Detailed discussion of the mathematical models for precipitate and adsorption colloid flotation alone could fill a complete text. The modeling is generally complex and requires varying amounts of computer time to complete. Therefore, in this chapter we present the overall approach and some resulting major mathematical relationships that can help maximize operating efficiency. 

Shkolin, A.V. and Fomkin, A.A. 2009. Deformation of AUK microporous carhon adsorbent induced by methane adsorption. Colloid. J. 71 119-124. 

Reichenauer G, Scherer G W (2001) Extracting the pore size distribution of compliant materials from nitrogen adsorption. Colloids and Surfaces A, 187-188 41-50. 

Barrett E P, Joyner L G, Halenda P P (1951) The Determination of Pore Volume and Area Distributions in Porous Substances. 1. Computations from Nitrogen Isotherms. J. Am. Chem. Soc. 73 373-380 Reichenauer G, Scherer G W (2001) Extracting the pore size distribution of compliant materials from nitrogen adsorption. Colloids and Surfaces a-Physicochemical and Engineering Aspects 187 41-50 Scherer G W, Smith D M, Stein D (1995) Deformation of Aerogels during Characterization. Journal of Non-CrystaUine Solids 186 309-315... 

Wang, X. Wu, G. Lu, C. Wang, Y Fan, Y Gao, H. Ma, J. Synthesis of a novel zwitterionic biodegradable poly (alpha,beta-L-aspartic acid) derivative with some L-histidine side-residues and its resistance to non-specific protein adsorption. Colloids Surf. B 2011, 86, 237-241. 

Gref R, Luck M, Quellec P, Marchand M, Dellacherie E, Hamisch S, et al. Stealth corona-core nanoparticles surface modified by polyethylene glycol (PEG) influences of the corona (PEG chain length and surface density) and of the core composition on phagocytic uptake and plasma protein adsorption. Colloids Surf B Biointerfaces October 1, 2000 18(3 ) 301-13. 

Sun J, Rao S, Su Y, Xu R, Yang Y Magnetic carboxymethyl chitosan nanopaiticles with immobilized metal ions for lysozyme adsorption. Colloids Surf A Physicochem Eng Asp. 2011 389(l-3) 97-103. 

Vazquez, MI de Lara, R Galan, P Benavente, J. Modification of cellulosic membranes by y-radiation Effect on electrochemical parameters and protein adsorption. Colloids and Surfaces A Physicochem. Eng. Aspects, 2005, 270-271,245-251. 

Terashima M, Fuknshima M, Tanaka S (2004) Influence of pH on the surface activity of humic acid micelle-like aggregate formation and interfacial adsorption. Colloids Surf A... 

Miller R, Kretzschmar G (1980) Numerische Losimg fur ein gemischtes ModeU der diffusions-kinetik-kontroUierten Adsorption. Colloid Polym Sd 258 85—87... 

Ducker, W. A. and Clarke, D. R., Controlled modification of silicon nitride interactions in water via zwitteri-onic surfactant adsorption. Colloid Surf., A, 93, 275-292 (1994). 

The various regimes and effects obtained for the interaetion of polymer solutions between two surfaces have recently been reviewed [55]. It transpires that force-microscope experiments done on adsorbed polymer layers form an ideal tool for investigating the basic mechanisms of polymer adsorption, colloidal stabilization, and flocculation. 

Menon, V.B. and Wasan, D.T (1986) Particle fluid interactions with application to solid-stabilized emulsions 1. The effect of asphaltene adsorption. Colloids and Surfaces, 19, 89—105. 

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