Sorption phenomena

Table I summarizes some typical distribution coefficients. Sediments become enriched in plutonium with respect to water, usually with a factor of vlO5. Also living organisms enrich plutonium from natural waters, but usually less than sediments a factor of 103 - 101 is common. This indicates that the Kd-value for sediment (and soil) is probably governed by surface sorption phenomena. From the simplest organisms (plankton and plants) to man there is clear evidence of metabolic discrimination against transfer of plutonium. In general, the higher the species is on the trophic level, the smaller is the Kd-value. One may deduce from the Table that the concentration of plutonium accumulated in man in equilibrium with the environment, will not exceed the concentration of plutonium in the ground water, independent of the mode of ingestion.

For plutonium in the tri- and tetravalent state, when hydrolysis would dominate the solution chemistry, most sorption phenomena in geologic systems can be looked upon largely as physical adsorption processes. Ion exchange processes, as defined above, would be... 

This study allows a better understanding of the Ni geochemistry in near-neutral conditions. Kinetic cell tests run for 75 weeks on 6 waste rock samples suggest that the pH will remain near neutral in the waste rock piles. Sorption phenomena seem to drive Ni leaching in laboratory kinetic cells, and the sorption type and capacity vary between fresh and... 

The interaction and sorption of metal ions with metal oxide and clay surfaces has occupied the attention of chemists, soil scientists, and geochemists for decades (1-4). Transition metal oxides receiving particular emphasis have included various oxides of manganese and iron (5). Interest in sorption phenomena is promoted by the desire to better understand incorporation of metals into minerals, especially marine deposits ( ), the removal of trace metal pollutants and radionuclides from rivers and streams, via sorption and/or precipitation phenomena (1,6), and the deposition of metals on solid substrates in the preparation of catalysts (7,8). 

Adsorption mechanisms represent probably the most important interaction phenomena exerted by solid surfaces on the environmental fate of organic pollutants [65, 127-130]. Adsorption controls the quantity of free organic components in solution and thus determines their persistence, mobility, and bioavailability. The extent of adsorption depends on the amount and properties of both solid phase-humic substances (SPHS) and organic pollutants. Once adsorbed on an SPHs >an organic pollutant may be easily desorbed, desorbed with difficulty, or not at all. Thus sorption phenomena may vary from complete reversibility to total irreversibility. 

These conclusions have several implications for pesticide waste disposal considerations. For incidental or accidental disposal of pesticides in natural aquatic systems, the results suggest that model calculations using aqueous solution values for abiotic neutral hydrolysis rate constants can be used without regard to sorption to sediments. For alkaline hydrolysis, on the other hand, models must explicitly include sorption phenomena and the correspond ng rate reductions in order to accurately predict hydrolytic degadation. 

Besides liquid and solid (snow, ice) water surfaces, mineral surfaces play the most important role with respect to adsorption processes involving gaseous organic compounds in the environment. Thus, a brief description of the chemical nature of mineral surfaces is helpful to understand our subsequent discussion of such sorption phenomena. 

Kopinke, F.-D., J. Porschmann, and A. Georgi, Application of SPME to study sorption phenomena on dissolved humic organic matter . In Applications of Solid Phase Microextraction, J. Pawliszyn, Ed., Royal Society of Chemistry, Cambridge. UK, 1999, pp. 111-128. 

Although the above studies conducted with packed columns are important from a fundamental standpoint as they relate to the mechanisms of cell sorption to solid surfaces, in situ remediation of contaminants in subsoils requires microbial transport in well-structured soils. The presence of soil macropores that facilitate preferential water flow is well appreciated (Thomas Phillips, 1979). Sorption phenomena are less important when bacterial transport occurs through structured soils in which cells pass unimpeded through relatively large conduits (Smith et al., 1985). 

Weber, W.J., P.M. McGinley, and L.E. Katz. 1991. Sorption phenomena in subsurface systems -concepts, models and effects on contaminant fate and transport. Water Res. 25(5) 499-528. 

All the previous theoretical considerations have been established assuming an ideal system without any boundary conditions. It should be pointed out however that in practice, all the studied systems, especially in SHE chemistry, have finite dimensions (time and volume). As only ideal system were considered, edge effects, pseudo-colloid formation, sorption phenomena, redox processes with impurities or surfaces, medium effects have not been taken into account. All these effects, representing the most important part from the deviation to ideality, cannot be predicted with formal thermodynamics and/or kinetics. Thus, radiochemists who intend to perform experiments at the scale of one atom must be aware that the presence of any solid phase (walls of capillary tubes, vessels, etc.) can perturb the experimental system. It is important to check that these edge effects are negligible at tracer level before performing experiments at the scale of the atom [11]. The following section describes experimental techniques used in SHE chemistry. 

Refs. [i] Inzelt G (2005) / Solid State Electrochem 9 245 [ii] Horanyi G (1980) Electrochim Acta 25 45 [iii] Horanyi G (2004) In Horanyi G (ed) Radiotracer studies of interfaces. Elsevier, Amsterdam, chapters 1,2,4,6 [iv] Horanyi G (2002) State of art present knowledge and understanding. In Bard AJ, Stratmann M, Gileadi E, Urbakh M (eds) Thermodynamics and electrified interfaces. Encyclopedia of electrochemistry, vol. 1. Wiley-VCH, Weinheim, Chap. 3 [v] Horanyi G (1999) Radiotracer studies of adsorption/sorption phenomena at electrode surfaces. In Wieckowski A (ed) Interfacial electrochemistry. Marcel Dekker, New York, pp 477 [vi] Horanyi G, Inzelt G (1978) / Electroanal Chem 87 423 [vii] Horanyi G, Inzelt G, Szetey E (1977) / Electroanal Chem 81 395 [viii] Vertes G, Horanyi G (1974) / Electroanal Chem 52 47 [ix] Horanyi G (1994) Catal Today19 285 [x] Horanyi G (2003) Electrocatalysis - heterogeneous. In Horvath IT (ed) Encyclopedia of catalysis, vol. 3. Wiley Interscience, Hoboken, pp 115-155 [xi] Inzelt G, Horanyi G (2006) The nickel group (nickel, palladium, and platinum). In Bard AJ, Stratmann M, Scholz F, Pickett CJ (eds) Inorganic chemistry. Encyclopedia of electrochemistry, vol 7a. Wiley-VCH, Weinheim, chap. 18... 

Refs. [i] Horanyi G (1999) Radiotracer studies of adsorption/sorption phenomena at electrode surfaces. In Wieckowski A(ed) Interfacial electrochemistry, theory, experiment, and applications. Marcel Dekker, New York, pp 477-491 [ii] Kalman E, Lakatos M, Karman FH, Nagy F, Klenc-sar Z, Virtes A (2005) Mossbauer spectroscopy for characterization of corrosion products and electrochemically formed layers. In Freund HE, Zewi I (eds) Corrosion reviews. Freund Publishing House, Tel Aviv, pp 1-106 [iii] Horanyi G, Kalman E (2005) Recent developments in the application of radiotracer methods in corrosion studies. In Marcus PH, Mansfeld F (eds) Analytical methods in corrosion science and engineering, CRC Press, Boca Raton, pp 283-333 [iv] Stivegh K, Horanyi TS, Vdrtes A (1988) Electrochim Acta 33 1061... 

Since SOM is most often the main component responsible for sorption of organic chemicals, e.g., contaminants (Fig. 4.19), researchers use octanol (an eight-carbon alcohol) to simulate organic matter-hydrophobic contaminant sorption phenomena. 

Figure 1-10 BET Monolayer Plot. Source From T.P. Labuza, Sorption Phenomena in Foods, Food Technol., Vol. 22, pp. 263-272, 1968.

Labuza, T.P. 1968. Sorption phenomena in foods. Food Technol. 22 263-272. 

The x-parameter has been related to gas sorption phenomena in polymers using a variation of Eq. 10 obtained by substituting RT In (P/P0)for(p — p ) to give ... 

Tamura T. (1972) Sorption phenomena significant in radioactive-waste disposal. In Underground Waste Management and Environmental Implications, American Association of Petroleum Geologists (ed. T. D. Cook). Tulsa, Oklahoma, pp. 318-330. 

Sorption heat pipe is a novelty and combines the enhanced heat and mass transfer typical for conventional heat pipe with sorption phenomena in the sorbent structure. The sorption heat pipe parameters are insensitive to some g acceleration and such heat pipe can be suggested for space and ground application. 

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