Hostname: page-component-586b7cd67f-t7czq Total loading time: 0 Render date: 2024-11-22T12:31:16.298Z Has data issue: false hasContentIssue false

Dehydration, Diffusion and Entrapment of Zinc in Bentonite

Published online by Cambridge University Press:  28 February 2024

Y. B. Ma
Affiliation:
School of Agriculture, La Trobe University, Bundoora, Victoria 3083, Australia
N. C. Uren
Affiliation:
School of Agriculture, La Trobe University, Bundoora, Victoria 3083, Australia
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

Interactions with bentonite are important in the chemical speciation and fate of heavy metals in soils and other ecosystems. The interactions of Zn with bentonite were studied using X-ray diffraction (XRD), dehydration, kinetic and sequential extraction procedures. The species and activity of Zn retained by bentonite were affected markedly by pH. The Zn(OH)+ was retained by bentonite prepared at pH ≥ 6.9. The extent of dehydration of Zn(OH)+-bentonite was higher than that for Zn-bentonite. At a relative humidity of 55.5%, the basal spacing of the Zn(OH)+-bentonite was from 1.21 to 1.26 nm with 1 water sheet and that of the Zn-bentonite was 1.51 nm with 2 water sheets. The greater affinity of Zn(OH)+ for bentonite than Zn was associated with a lower degree of hydration. When an aqueous suspension of Ca-bentonite was incubated with soluble Zn, the concentration of Zn retained by the Ca-bentonite was linearly related to the square root of time. The rate of the interaction was controlled probably by the interlayer diffusion and subsequently by the diffusion into the ditrigonal cavities in bentonite. The Zn retained by bentonite was dehydrated in situ so as to increase the bonding of Zn with surfaces of bentonite. With hydrothermal treatment the retained Zn could diffuse easily into the cavities and transform increasingly to the residual forms that are associated with the entrapped form.

Type
Research Article
Copyright
Copyright © 1998, The Clay Minerals Society

References

Bain, D.C. Smith, B.F.L. and Wilson, M.J., 1994 Chemical analysis Clay mineralogy: Spectroscopic and chemical determinative methods London. Chapman & Hall 300332 10.1007/978-94-011-0727-3_8.CrossRefGoogle Scholar
Ben Hadj-Amara, A. Besson, G. and Tchoubar, C., 1987 Caractéristiques structurales d’une smectite dioctaèdrique en fonction de Tordre-désordre dans la distribution des charges électriques: Études des reflexions 001 Clay Miner 22 305318 10.1180/claymin.1987.022.3.05.CrossRefGoogle Scholar
Calvet, R. and Prost, R., 1971 Cation migration into empty octahedral sites and surface properties of clays Clays Clay Miner 19 175186 10.1346/CCMN.1971.0190306.CrossRefGoogle Scholar
Crank, J., 1975 The Mathematics of diffusion .Google Scholar
Denis, J.H. Keall, M.J. Hall, P.L. and Meeten, G.H., 1991 Influence of potassium concentration on the swelling and compaction of mixed (Na, K) ion-exchanged montmorillonite Clay Miner 26 255268 10.1180/claymin.1991.026.2.09.CrossRefGoogle Scholar
Dixon, J.B. and Weed, S.B., 1989 Minerals in soil environments 2nd.CrossRefGoogle Scholar
Farmer, V.C., Greenland, D.J. and Hayes, M.H.B., 1978 Water on particle surfaces The Chemistry of soil constituents New York J. Wiley 405448.Google Scholar
Farrah, H. and Pickering, W.F., 1976 The sorption of zinc species by clay minerals Aust J Chem 29 16491656 10.1071/CH9761649.CrossRefGoogle Scholar
Frenkel, M., 1974 Surface acidity of montmorillonites Clays Clay Miner 22 435441 10.1346/CCMN.1974.0220510.CrossRefGoogle Scholar
Koryta, J. and Dvorák, J., 1987 Principles of electrochemistry Great Britain J. Wiley 10.1016/S0003-2670(00)85924-3.CrossRefGoogle Scholar
Luca, V. and Cardile, C.M., 1989 Cation migration in smectite minerals: Electron spin resonance of exchanged Fe3+ probes Clays Clay Miner 37 325332 10.1346/CCMN.1989.0370405.CrossRefGoogle Scholar
Newman, A.C.D. Brown, G. and Newman, A.C.D., 1987 The chemical constitution of clays Chemistry of clays and clay minerals 1128.Google Scholar
Pass, G., 1973 Ions in solution (3): Inorganic properties Oxford Clarendon Pr..Google Scholar
Quirk, J.P. Posner, A.M., Nicholas, D.J.D. and Egan, A.R., 1975 Trace element adsorption on mineral surfaces Trace elements in soil-plant-animal systems New York Academic Pr. 95107 10.1016/B978-0-12-518150-1.50012-4.CrossRefGoogle Scholar
Reddy, M.R. and Perkins, H.E., 1974 Fixation of zinc by clay minerals Soil Sci Soc Am Proc 38 229231 10.2136/sssaj1974.03615995003800020011x.CrossRefGoogle Scholar
Tan, K.H., 1993 Principles of soil chemistry 2nd New York Marcel Dekker.Google Scholar
Tiller, K.G. Gerth, J. and Bruemmer, G., 1984 The relative affinity of Cd, Ni and Zn for different soil clay fractions and goe-thite Geoderma 34 1735 10.1016/0016-7061(84)90003-X.CrossRefGoogle Scholar
Tiller, K.G. and Hodgson, J.E., 1962 The specific sorption of cobalt and zinc by layer silicates Clays Clay Miner 9 393403 10.1346/CCMN.1960.0090126.CrossRefGoogle Scholar