Hostname: page-component-76fb5796d-vfjqv Total loading time: 0 Render date: 2024-04-25T12:22:13.123Z Has data issue: false hasContentIssue false

Surface fractal dimensions of synthetic clay-hydrous iron oxide associations from nitrogen adsorption isotherms and mercury porosimetry

Published online by Cambridge University Press:  09 July 2018

R. Cells
Affiliation:
Instituto de Recursos Naturales y Agrobiologia de Sevilla, CSIC, P.O. Box 1052, E-41080 Sevilla, Spain
J. Cornejo
Affiliation:
Instituto de Recursos Naturales y Agrobiologia de Sevilla, CSIC, P.O. Box 1052, E-41080 Sevilla, Spain
M. C. Hermosin
Affiliation:
Instituto de Recursos Naturales y Agrobiologia de Sevilla, CSIC, P.O. Box 1052, E-41080 Sevilla, Spain

Abstract

Model associations of layer silicates (kaolinite and montmorillonite) and iron oxyhydroxides were obtained by precipitating hydrous iron oxide in clay suspensions at different loading. The porosity of these clay-hydrous iron oxide associations was studied in the macro- and mesopore range by mercury intrusion porosimetry (MIP) and in the micropore region by nitrogen adsorption isotherms, being the fractal geometry applied to the approaches used in porosity studies. Results of nitrogen adsorption isotherms showed that surface area and microporosity of kaolinite and montmorillonite increased upon Fe precipitation, especially for montmorillonite. This process is accompanied by an increase in the surface fractal dimension Ds(N2) by the presence of hydrous iron oxide coating the clay particles. Results of MIP also showed a decrease in the pore volume by Fe precipitation on montmorillonite due to a decrease in the number of large pores and a development of new medium-size pores. An increase of the fractal dimension Ds(Hg) was also observed.

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1996

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Avnir, D., Farin, D. & Pfeifer, P. (1984) Molecular fractal surfaces. Nature, 308, 261263.CrossRefGoogle Scholar
Avnir, D. & Jaroniec, M. (1989) An isotherm equation for adsorption on fractal surfaces of heterogeneous porous materials. Langmuir, 5, 1431–1433.Google Scholar
Bartoli, F., Philippy, R. & Burtin, G. (1992) Poorly ordered hydrous Fe oxides, colloidal dispersion and soil aggregation.It. Modification of silty soil aggregation with Fe(III) polycations and model humic macromolecules. J. Soil Sci. 43, 59–75.Google Scholar
Bartoli, F., Philippy, R., Doirisse, M., Niquet, S. & Dubuit, M. (1991) Structure and self-similarity in silty and sandy soils: the fractal approach. J. Soil Sci. 42, 167185.Google Scholar
Ben Ohoud, M. & Van Damme, H. (1990) The fractal texture of swelling clays and clay-organic aggregates. C.R. Acad. Sci. Paris, 311, series II, 665-670.Google Scholar
Brunauer, S., Emmett, P.H. & Teller, E. (1938) Adsorption of gases in multimolecular layers. J. Am. Chem. Soc. 60, 309319.CrossRefGoogle Scholar
Brunauer, S., Deming, L.S., Deming, W.S. & Teller, E. (1940) On a theory of the Van der Waals adsorption of gases. J. Am. Chem. Soc. 62, 17231732.Google Scholar
Burrough, P.A. (1981) Fractal dimensions of landscapes and other environmental data. Nature, 294, 240242.Google Scholar
Cornejo, J. (1987) Porosity evolution of thermally treated hydrous ferric oxide gel. J. Coll. lnterfi Sci. 115, 260263.Google Scholar
Cornejo, J., Serna, C.J. & Hermosin, M.C. (1984) Nitrogen adsorption on synthetic ferrihydrite. J. Coll. lnterf. Sci. 94, 546551.Google Scholar
Cox, L., Celis, R., Hermosin, M.C. & Cornejo, J. (1996) Porosity, sorption and surface fractal properties of soils as factors affecting mobility of herbicides. Eur. J. Soil Sci. (submitted).Google Scholar
De Gennes, P.G. (1985) Partial filling of a fractal structure by a wetting fluid. Pp. 227–241 in: Physics of Disordered Materials. (Adler, D. et al., editors). Plenum Press, New York.Google Scholar
Desphande, T.L., Greenland, D.J. & Quirk, J.P. (1964) Role of iron oxides in the bonding of soil particles. Nature, 201, 107108.Google Scholar
Dubinin, M.M. (1988) Characterization of Porous Solids. (Unger, K.K., Rouquerol, J., Sing, K.S.W. & Kral, H., editors). Elsevier, Amsterdam.Google Scholar
El Rayan, H.M.E. & Rowell, D.L. (1973) The influence of iron and aluminum hydroxides on the swelling of Na-montmorillonite and the permeability of a Nasoil. J. Soil Sci. 24, 137144.Google Scholar
Friesen, W.I. & Mlula, R.J. (1987) Fractal dimensions of coal particles. J. Coll. lnterfi. Sci. 120, 263271.Google Scholar
Goldberg, S. & Glaubig, R.A. (1987) Effect of saturating cation, pH, and aluminum and iron oxide on the flocculation of kaolinite and montmorillonite. Clays Clay Miner. 35, 220227.Google Scholar
Gregg, S.J. & Sing, K.S.W. (1982) Adsorption, Surface Area and Porosity, pp. 89–90. Academic Press Inc., London.Google Scholar
Horvath, G. & Kawazoe, K. (1983) Method for the calculation of effective pore size distribution in molecular sieve carbon. J. Chem. Eng. Japan, 16, 470475.Google Scholar
Lefebvre, Y., Lacelle, S. & Jolicoeur, C. (1992) Surface fractal dimensions of some industrial minerals from gas-phase adsorption isotherms. J. Mat. Res. 7, 18881891.Google Scholar
Mandelbrot, I. (1982) The Fractal Geometry of Nature. Freeman, San Francisco.Google Scholar
Pfeifer, P. & Avnir, O. (1983) Chemistry in noninteger dimensions between two and three. J. Chem. Phys. 79, 35583565.Google Scholar
Shahmuganathan, R.T. & Oades, J.M. (1982) Modification of soil physical properties by manipulating the net surface charge on colloids through addition of Fe(III) polycations. J. Soil Sci. 33, 451465.Google Scholar
Shepard, S.J. (1993) Using a fractal model to compute the hydraulic conductivity function. Soil Sci. Soc. Am. J. 57, 300306.Google Scholar
Srasra, E., Bergaya, F., Van Damme, H. & Ariguib, N.K. (1989) Surface properties of an activated bentonitedecolorisation of rape-seed oils. Appl. Clay Sci. 4, 411421.Google Scholar
Van Damme, H., Levrrz, P., Gattneau, L., Alcover, J.F. & Fripiat, J.J. (1988) On the determination of the surface fractal dimension of powders by granulometric analysis. J. Coll. lnte.rfi Sci. 122, 18.Google Scholar
Van Olphen, H. & Fripiat, J.J. (1979) Data Handbook for Clay Materials and other Non-Metallic Minerals. OECD and Clay Minerals Society. Pergamon Press, Oxford.Google Scholar
Washburn, E.W. (1921) Note on a method of determining the distribution of pore sizes in a porous material. Proc. Nat. Acad. Sci. U.S.A. 7, 115-116.Google Scholar
Young, I.M. & Crawford, J.W. (1991) The fractal structure of soil aggregates: its measurement and interpretation. J. Soil Sci. 42, 187192.Google Scholar