Montmorillonite, sorption

Fig. 10-9. Corresponding Np(V)- and U(VI)-montmorillonite sorption coefficients (K in mL x g ) calculated with M1NTEQA2 using DLM parameters given in Table 10-1. Solid line shows linear regression In (he (lata with 95% prediction limits (dotted lines). Dashed line shows Log Ai a.iKvi) = Log ii,N i( V) l"i tcleiciuT. Water chemistry based on 460 iinalyses developeil from (he data of Perfect et al, (1995)...

Of the various inorganic soil constituents, smectites (montmorillonite clays) have the greatest potential for sorption of pesticides on account of their large surface area and abundance in soils. Weak base pesticides, both protonated and neutral species, have been shown to be sorbed as interlayer complexes. Sorption of atrazine on smectites ranges from 0 to 100% of added atrazine, depending on the surface charge density of the smectite (36). 

Sorption of plutonium (l.fixlO-11 M) and americium (2xl0-9 M) in artificial groundwater (salt concentration 300 mg/liter total carbonate 120 mg/liter Ref. 59) on some geologic minerals, quartz, biotite, o apatite, o attapulgite, montmorillonite. Dashed lines indicate the range for major minerals in igneous rocks. Experimental conditions room temperature, particle size 0.04-0.06 mm, solid/liquid ratio 6-10 g/1, aerated system, contact time 6 days. 

Bioreactors containing an nndefined anaerobic consortinm rednced TNT to 2,4,6-triaminotoluene (TAT) in the presence of glncose (Dann et al. 1998). The sorption of TAT to montmorillonite clay was irreversible, and the snbstrate conld not be released by solvent extraction or by acid or alkaline treatment. Similar resnlts were obtained with humic acids in which covalent reactions with carbonyl or activated C=C bonding presumably occurred. Results from laboratory experiments nsing i C-labeled TNT in reactors to which... 

When organic cations (e.g., cationic tensides) are employed, clay organo-complexes are formed, which can be used in organic solvents. A Pd-hexadecy-lammonium montmorillonite catalyst was prepared by the reduction of Pd(OAc)2 by ethanol in the interlamellar space. At small ethanol concentrations in toluene, selective interlamellar sorption of ethanol was established consequently, the reduction also occurred only in the interlamellar space.160 The catalyst was used for the hydrogenation of alkenes.161... 

Goldberg (2002) found no evidence of any competition in sorption of arsenate and arsenite on Al or Fe-oxides and montmorillonite, but only a small and apparent competitive effect of equimolar arsenate on arsenite sorption on kaolinite and illite. The minor competitive effect in this study was due to the small concentrations of arsenic which is very low for saturation site. Competition for sorption sites is evident by increasing the surface coverage of the sorbents. Arsenate prevents arsenite sorption on metal oxides when the surfaces of the sorbents are saturated by the anions (Jain and Loeppert 2000 Violante and Pigna 2002). 

In addition to SOM, clay minerals are another important component that may influence contaminant-soil interactions. Expandable 2 1 type clays are usually more reactive than other clay minerals. Park et al. (2003) used a K-saturated montmorillonite as a sorbent to evaluate the availability of sorbed atrazine to three atrazine-degrading bacteria. K-saturated montmorillonite has a high atrazine sorption capacity with a Freundlich sorption... 

Oudou HC, Hansen HC (2002) Sorption of /ambda-cyhalothrin, cypermethrin, deltamethrin and fenvalerate to quartz, comndum, kaolinite and montmorillonite. Chemosphere 49 1285-1294... 

Sorption depends on Sorption Sites. The sorption of alkaline and earth-alkaline cations on expandable three layer clays - smectites (montmorillonites) - can usually be interpreted as stoichiometric exchange of interlayer ions. Heavy metals however are sorbed by surface complex formation to the OH-functional groups of the outer surface (the so-called broken bonds). The non-swellable three-layer silicates, micas such as illite, can usually not exchange their interlayer ions but the outside of these minerals and the weathered crystal edges ("frayed edges") participate in ion exchange reactions. 

The data are "normalized" with regard to the ion exchange capacity C of the sorbents. The sorption curves of the illite and of the < 40-pm chlorite are strongly non-linear, whereas that of the montmorillonite approaches linearity. 

Ulrich, H.-J., and C. Degueldre (1987), "The Sorption of 210Pb, 210Bi and 21°Po on Montmorillonite A Study with Emphasis on Reversibility Aspects and on the Effect of the Radioactive Decay of Adsorbed Nuclides", submitted. 

Bar-Yosef B, Meek D (1987) Selenium sorption by kaolinite and montmorillonite. Soil Sci (144) 11-19 Beard BL, Johnson CM (2004) Fe isotope variations in the modem and ancient earth and other planetary bodies. Rev Minerd Geochem 55 319-357... 

The amount of adsorbed chemical is controlled by both properties of the chemical and of the clay material. The clay saturating cation is a major factor affecting the adsorption of the organophosphorus pesticide. The adsorption isotherm of parathion from an aqueous solution onto montmorillonite saturated with various cations (Fig. 8.32), shows that the sorption sequence (Al > Na > Ca ) is not in agreement with any of the ionic series based on ionic properties. This shows that, in parathion-montmoriUonite interactions in aqueous suspension, such factors as clay dispersion, steric effects, and hydration shells are dominant in the sorption process. In general, organophosphorus adsorption on clays is described by the Freundhch equation, and the values for parathion sorption are 3 for Ca +-kaoUnite, 125 for Ca -montmorillonite, and 145 for Ca -attapulgite. 

Saltzman S, Yariv S. 1975. Infrared study of the sorption of phenol and p-nitrophenol by montmorillonite. Soil Sci Society of America Proceedings 39 474-479. 

Bond and coworkers [521] have described Au(III) electroreduction and Au(0) oxidation stripping processes in dilute aqua regia utilizing platinum, rhodium, iridium, gold, and glassy carbon electrodes. Sorption of tetrachloroaureate ions on carbon paste electrode modified with montmorillonite has been performed as a preconcentration step in the determination of gold in pharmaceutical preparation [522]. 

Chisholm-Brause, C. J., Berg, J. M., Matzner, R. A. Morris, D. E. 2001. Uranium(VI) sorption on montmorillonite as a function of solution chemistry. Journal of Colloid and Interface Science, 233, 38-49. 

Degueldre, C., Ulrich, H. G. Silby, H. 1994. Sorption of 243Am onto montmorillonite, illite and hematite colloids. Radiochimica Acta, 65, 173-179. 

Minerals VIII. A Consistency Test of Exchange Sorption in the Systems Sodium-Cesium-Barium Montmorillonite," J. Phys. Chem., (1963), 1781. 

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