Adsorption behaviour

On the basis of available data, it would appear that there are several possible reasons that may account for the observed decrease in surface activity of proteins, depending on the strengths of their thermodynamically favourable interactions with different polysaccharides. In the case of a rather weak interaction, which does not lead to the formation of a stable complex between protein and polysaccharide, the decrease in the surface activity of protein is evidently determined by the corresponding 

The expected greater size of protein-polysaccharide complexes can reduce the diffusion rate of the adsorbing species towards the interface. This effect is especially important for small monomeric proteins. In addition, Ganzevles and co-workers (2006) have suggested that the diffusion of protein in the complexes may not solely be responsible for the slow surface tension decay. Rather, the gradual dissociation (and subsequent adsorption) of protein from complexes, when they are in close proximity to the interface, could also contribute to the behaviour. 

It was also demonstrated that the reduced surface activity of the protein did not affect the protein loading significantly (see Table 3.1 in chapter 3) (Semenova et al., 1999a,b), or at the very least only slightly reduced it (Jourdain et al., 2008, 2009). That is, for sodium caseinate (0.5 wt%) + dextran sulfate (1 wt%), the lower surface activity of the 

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The number and kind of defects in a given specimen, as well as the crystal habit and with it the proportion of different crystal faces exposed, will in general depend in considerable degree on the details of preparation. The production of a standard sample of a given chemical substance, having reproducible adsorptive behaviour, remains therefore as much an art as a science. 

Hoch M, Alonso-Azcarate J, Lischick M (2003) Assessment of adsorption behaviour of dibutyltin (DBT) to clay-rich sediments in comparison to the highly toxic tributyltin (TBT). Environmental Pollution, 123(2) 217-227. 

Pershina, V., Bastug, T., Sarpe-Tudoran, C., Anton, J. and Fricke, B. (2004) Predictions of adsorption behaviour of the superheavy element 112. Nuclear Physics... 

Catalysis. Beitel et al. (1997) have employed RAIRS to study in situ the co-adsorption behaviour of CO and hydrogen on single-crystal cobalt (0001) catalysts at pressures up to 300mbar and temperatures between 298 and 490 K. The behaviour of these adsorbates is of considerable importance in relation to their commercial importance as catalysts for the Fischer-Tropsch reaction in the... 

Whether the adsorption of molecules at the surface of minerals is a curse or a blessing for the adsorbed substances depends on many parameters. Experiments showed very different adsorption behaviour of adenine on different minerals. Active minerals are of particular importance for hydrothermal processes (see Sect. 7.2). The surface concentration of adenine on pyrites is fifteen times, that on quartz five times, and on pyrrhotite three and a half times as high as in a starting solution whose concentration is 20 pM (Cohn, 2002). 

Table 2. Some properties of proteins relevant for their adsorption behaviour...

The understanding of activation effects on the electrochemical behaviour of ordered platinum surfaces will allow the possibility of correlating the classical knowledge of platinum adsorption behaviour with the new observations. 

In the range of linear adsorption behaviour, whatever the number of site types (see Section 2.3.1 for the merging of parameters of two sites), the surface concentration F is related to via an effective linear coefficient, Ah, while the first-order internalisation processes can also be described by an effective first-order constant, k. Thus, equation (39) can be recast, for instance, in terms of r as ... 

Ross, J. M. and Sherrell, R. M. (1999). The role of colloids in trace metal transport and adsorption behaviour in New Jersey Pinelands streams, Limnol. Oceanogr., 44, 1019-1034. 

Chauhan, S.S., Aggrawal, P., Karmarkar, A. and Pandey, K.K. (2001). Moisture adsorption behaviour of esterified rubber wood (Hevea brasiliensis). Holz als Roh- und Werkstoff, 59(4), 250-253. 

Yu Runlan, Qiu Guanzhou, Hu Yuehua, Qin Wenqing, 2005. Electrochemical adsorption behaviour and mechanism of diethyldithiocarbamate on surface of marmatite. The Chinese Journal of Nonferrous Metals, 15(9) 1452 - 1457 (in Chinese)... 

The adsorption data is often fitted to an adsorption isotherm equation. Two of the most widely used are the Langmuir and the Freundlich equations. These are useful for summarizing adsorption data and for comparison purposes. They may enable limited predictions of adsorption behaviour under conditions other than those of the actual experiment to be made, but they provide no information about the mechanism of adsorption nor the speciation of the surface complexes. More information is available from the various surface complexation models that have been developed in recent years. These models represent adsorption in terms of interaction of the adsorbate with the surface OH groups of the adsorbent oxide (see Chap. 10) and can describe the location of the adsorbed species in the electrical double layer. 

The selenite and sdenate ions illustrate the effect of oxidation state on adsorption behaviour. The selenite ion (SeO ) adsorbs strongly and specifically on goethite and shifts the iep of both goethite and ferrihydrite to lower pH values (Su and Suarez,... 

The adsorption behaviour of 1,2,4,5-tetra carboxylic and 2,3-dihydroxybenzoic acids most closely simulated that of NOM (Evanko and Dzombak, 1998). Another modelling study, this time with CD-MUSIC, suggested that adsorption of carboxylic acids on goethite involved two complexes located on different crystal planes, viz. a deprotonated outer sphere complex (pH 3-9) and an inner sphere mononuclear chelate present at ca. pH 6 (Boily et al., 2000). 

In general, the adsorption behaviour of gases on iron oxides has been investigated either because the gases are atmospheric pollutants (NO, SO2, CO2), or because they act as probe molecules and provide information about surface sites. The adsorption sites on iron oxides are usually the Lewis acid sites. 

Takahashi, Y., Minai, Y, Ambe, S., Makide, Y. Ambe, F. 1999. Comparison of adsorption behaviour of multiple inorganic ions on kaolinite and silica in the presence of humic acids using the multiple sorption tracer technique. Geochimica et Cosmochimica Acta, 63, 815-836. 

Venema P. Charging and ion adsorption behaviour of different iron (hydr) oxides PhD. Thesis, Wageningen Agricultural University Wageningen, The Netherlands. 

Ganzevles, R.A., van Vliet, T., Cohen Stuart, M.A., de Jongh, H.H.J. (2007). Manipulation of adsorption behaviour at liquid interfaces by changing protein-polysaccharide electrostatic interactions. In Dickinson, E., Leser, M.E. (Eds). Food Colloids Self-Assembly and Material Science, Cambridge, UK Royal Society of Chemistry, pp. 195-208. 

Key points relating to the adsorption behaviour of proteins and their influence on colloid stability are summarized below (Dickinson, 1999a). 

The second example is the measurement of two zeolites of different size. This should illustrate the other extreme of adsorption behaviour, a material that has a negligible surface but a strong micropore adsorption. 

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