Desorption behavior

In general, the desorptive behavior of contaminated soils and soHds is so variable that the requited thermal treatment conditions are difficult to specify without experimental measurements. Experiments are most easily performed in bench- and pilot-scale faciUties. Full-scale behavior can then be predicted using mathematical models of heat transfer, mass transfer, and chemical kinetics. 

Berg M, Arnold CG, Muller SR, Muhlemann J, Schwarzenbach RP (2001) Sorption and desorption behavior of organotin compounds in sediment-pore water systems. Environmental Science and Technology, 35(15) 3151-3157. 

An important consideration prior to sample collection is transportation and storage. Samples should be treated so as to retain the integrity of the sample from the moment of collection to the time of analysis. The physico-chemical characteristics of a sediment sample change during drying, with effects on the sorption-desorption behavior of chemicals. 

Hou, P.X., S.T. Xu, Z. Ying, Q.H. Yang, C. Liu, H.M. Cheng, Hydrogen adsorption/desorption behavior of multi-walled carbon nanotubes with different diameters. Carbon 41,2471-2476,2003. 

Adsorption-Desorption Behavior of Polyvinyl Alcohol on Polystyrene Latex Particles... 

An important and recently reported issue, namely slow sorption/desorption rates, their causes at the intra-particle level of various solid phases, and how these phenomena relate to contaminant transport, bio availability, and remediation, is also discussed and evaluated. A case study showing the environmental impact of solid waste materials which are mainly complex organic mixtures and/or their reuse/recycling as highway construction and repair materials is presented and evaluated from the point of view of sorption/desorption behavior and data modeling. 

The main objectives of this chapter are to (1) review the different modeling techniques used for sorption/desorption processes of organic pollutants with various solid phases, (2) discuss the kinetics of such processes with some insight into the interpretation of kinetic data, (3) describe the different sorption/ desorption experimental techniques, with estimates of the transport parameters from the data of laboratory tests, (4) discuss a recently reported issue regarding slow sorption/desorption behavior of organic pollutants, and finally (5) present a case study about the environmental impact of solid waste materials/complex... 

Predicting sorption coefficients and hence the mobility of organic pollutants in aqueous-solid systems requires complete knowledge and analysis of various physical and chemical properties of such pollutants. This includes properties such as solubility, equilibrium vapor pressure, Henry s law constant, partition coefficient, as well as pKa and pKb values. Such properties can initially help determine the sorption-desorption behavior of organic pollutants once they are released, directly and/or indirectly, to the aqueous environment and then are in direct contact with solid phases. The following sections briefly summarize these properties. 

The Li-Mg-B-N-H structure possesses storage capacity of more than 10 wt.% at around 150-200 "C. However, the reversibility of the hydrogen sorption characteristics was determined using pressure-composition isotherms as shown in Figure 6. From this study, we found reversible hydrogen absorption-desorption behavior (-3-4 wt.%) of the new complex hydride Li-Mg-B-N-H. The improvement in temperature and reversible hydrogen storage capacity were unaffected even after ten... 

Tsuzuki, K., Eiki, H., Inoue, N., Sagara, A., Noda, N., Hirohata, Y, Hino T. 1999. Hydrogen absorption/desorption behavior with oxygen contaminated boron film. J Nuclear Mat 266-269 247-250. 

The effect of a ball-milling time on the DSC desorption behavior of undoped and Ni-doped MgH is shown in Fig. 2.52a. Endothermic desorption peak for the MgH + 5 wt.% m-Ni powder milled for 15 min is only modestly shifted to lower temperatures, showing the onset temperature at -350°C and the peak maximum at 392.8°C as compared to a pure MgH with the onset at 380°C and the maximum at 418.2°C, respectively, also milled for 15 min. In contrast, the hydrogen desorption peak for the MgH h- 5 wt.% n-Ni powder is substantially shifted to lower temperatures and shows the onset temperature at 170°C and the peak maximum at 243.1°C. However, when the MgH + 5 wt.% m-Ni powder is milled for 20 h, its desorption properties are much improved such that the onset is at 275°C and the peak maximum at 302.3°C (Fig. 2.52b). Apparently, longer milling time reduces desorption temperature, most likely due to a better dispersion of Ni particles within the MgHj matrix. Nevertheless, the desorption temperature of the 20 h milled MgH + 5 wt.% m-Ni powder is still worse than that of the 15 min milled MgH + 5 wt.% n-Ni. This clearly shows that n-Ni exhibits superb catalytic properties. 

F.C. Gennari, F.J. Castro, G. Urretavizcaya, Hydrogen desorption behavior from magnesium hydrides synthesized by reactive mechanical aUoying, J. Alloys Compd. 321 (2001) 46-53. 

Unfortunately, quite promising hydrogen desorption behavior in DSC as shown in Fig. 3.4 did not translate into desorption in a Sieverts-type apparatus as shown in Fig. 3.5. The powder milled sequentially for 270 h desorbed in a Sieverts-type apparatus at 250 and 290°C (Fig. 3.5) under primary vacuum only about 1.2 wt%Hj which is approximately a half of the hydrogen content obtained during DSC and TGA tests. No desorption of hydrogen was detected in a Sieverts-type apparatus at 250 and 290°C after 128 and 70 min, respectively, from the powder continuously milled for 270 h. The latter easily desorbed 3.13 and 2.83 wt%Hj in DSC and TGA... 

H.Y Leng, T. Ichikawa, S. Isobe, S. Hino, N. Hanada, H. Fujii, Desorption behaviors from metal-N-H systems synthesized by baU milling , J. Alloys Compd. 404 06 (2005) 443 47. 

Kenna, B. T. and F. J. Conrad. Studies of the Adsorption/Desorption Behavior of Explosive-Like Molecules. Sandia Report SAND86-0141, Sandia National Laboratories, Albuquerque, NM 1986. 

Padmanabham, M. (1983) Adsorption-desorption behavior of copper(Il) at the goethite-solution interface. Aust. J. Soil Res. 21 309-320... 

Table 11. Results of adsorption and desorption behavior of IgG on PHEMA and HA copolymers [130]...

Our previous study [130] on the adsorption and desorption behavior of bovine IgG has shown that the protein adsorbed to HA surface would be eluted quantitatively by 0.1 M PBS (phosphoric buffer solution) as shown in Table 11. Presumably, IgG molecules had been trapped in the destabilized network of water molecules on the surface of the HA copolymer. 

The reactivity of a surface depends on many factors. These include the adsorption energies of chemical species and their dissociation behavior, their diffusion on the surface, the adatom-adatom interactions, the active sites where a chemical reaction can occur, and the desorption behavior of a new chemical species formed on the surface. The site specificity depends on at least three factors the atomic configuration of the surface, the electronic structures of the surface, and the localized surface field. In atom-probe experiments, the desorption sites can be revealed by a timegated image of an imaging atom-probe as well as by an aiming study with a probe-hole atom-probe, the electronic structure effect of a chemical reaction can be investigated by the emitter material specificity, and the surface field can be modified by the applied field. 

Aochi, Y. O., and W. J. Farmer, Role of microstructural properties in the time-dependent sorption/desorption behavior of 1,2-dichloroethane on humic substances , Environ. Sci. Technol., 31,2520-2526 (1997). 

That several model organic compounds were only partially or incompletely retained by the resins prompted us to investigate the use of Carbopack B as an alternative or complementary adsorbent. Test solutions without humic acids were used to verify the sorptive-desorptive behavior of several model compounds under the experimental conditions proposed by Bacaloni et al. (8), except that the compounds were desorbed with methylene chloride. The results of duplicate experiments are given in Table III. Isophorone and MIBK were not effectively retained by Carbopack B, whereas bis(2-ethylhexyl) phthalate was almost equally distributed between the aqueous phase and the carbon. The relatively poor recovery of 1-chlorododecane, 2,4 -dichlorobiphenyl, and 2,2, 5,5 -tetrachlorobiphenyl may be ascribed to sorptive losses onto reservoir glass wall, whereas furfural may be inefficiently... 

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