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Stability constants for silicate adsorbed to ferrihydrite

Published online by Cambridge University Press:  09 July 2018

H. C. B. Hansen ,
T. P. Wetche ,
K. Raulund-Rasmussen  and
O. K. Borggaard
H. C. B. Hansen
Affiliation:
Chemistry Department, Royal Veterinary & Agricultural University, Thorvaldsensvej 40, DK-1871 Frdb. C., Copenhagen, Denmark
T. P. Wetche
Affiliation:
Chemistry Department, Royal Veterinary & Agricultural University, Thorvaldsensvej 40, DK-1871 Frdb. C., Copenhagen, Denmark
K. Raulund-Rasmussen
Affiliation:
Chemistry Department, Royal Veterinary & Agricultural University, Thorvaldsensvej 40, DK-1871 Frdb. C., Copenhagen, Denmark
O. K. Borggaard
Affiliation:
Chemistry Department, Royal Veterinary & Agricultural University, Thorvaldsensvej 40, DK-1871 Frdb. C., Copenhagen, Denmark
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Abstract

Intrinsic surface acidity constants (Kalintr, Ka2intr) and surface complexation constant for adsorption of orthosilicate onto synthetic ferrihydrite (Ksi for the complex ≡FeOSi(OH)3) have been determined from acid/base titrations in 0.001-0.1 M NaClO4 electrolytes and silicate adsorption experiments in 0.01 M NaNOi electrolyte (pH 3-6). The surface equilibrium constants were calculated according to the two-layer model by Dzombak ' Morel (1990). Near equilibrium between protons/hydroxyls in solution and the ferrihydrite surface was obtained within minutes while equilibration with silicate required days-weeks, both reactions probably being diffusion controlled. Applying the values for specific surface area and site densities for ferrihydrite used by Dzombak ' Morel (1990) (600 m2 g–1, 3.4 μmole m–2) the constants pKalintr = 6.93 ± 0.12, pKa2intr = 8.72 ± 0.17 and log Ksi = 3.62 were calculated by using the FITEQL optimization routine. Use of the specific surface area actually measured (269 m2 g-1) gave a poorer fit of the experimental data. Due to the slow adsorption of silicate and hence long shaking times, changes in the surface characteristics of the ferrihydrite seem to take place, probably a decrease in the concentration of surface sites. Adsorption isotherms calculated using the derived equilibrium constants showed that approximately twice the amount of silicate was adsorbed at pH 5 compared with pH 3.

Infrared spectroscopy of silica adsorbed to ferrihydrite showed Si-O stretching absorption maxima in the range 940-960 cm-1. The shift of the absorption maximum to higher wavenumbers with increasing amount of silicate adsorbed is probably due to an increase in the frequency of Si-O-Si bonds between orthosilicate adsorbed at adjacent sites. Small amounts of goethite were identified in the adsorption products.

Type
Research Article
Information
Clay Minerals , Volume 29 , Issue 3 , September 1994 , pp. 341 - 350
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1994

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References

Alexander, G.B. (1953) The reaction of low molecular weight silicic acids with molybdic acid. J. Am. Chem. Sot:. 75, 5655–5657.Google Scholar
Anderson, P.R. & Benjamin, M.M. (1985) Effects of silicon on the crystallization and adsorption properties of ferric oxides. Environ. Sci. Technol. 19, 1048–1053.CrossRefGoogle Scholar
Anderson, P.R. & Benjamin, M.M. (1990) Constant-capacitance surface complexation model. Adsorption in silica-iron binary oxide suspensions. ACS Symp. Ser. 416, 272–281.Google Scholar
Barrow, N.J. (1983) A mechanistic model for describing the sorption and desorption of phosphate by soil. J. Soil Sci. 34, 733–750.Google Scholar
Bolan, N.S., Barrow, N.J. & Posner, A.M. (1985) Describing the effect of time on sorption of phosphate by iron and aluminium hydroxides. J. Soil Sci. 36, 187–197.Google Scholar
Borggaard, O.K. (1990) Dissolution and adsorption properties of soil iron oxides. Thesis, DSR-Forlag, Copenhagen, Denmark.Google Scholar
Carlson, L. & Schwertmann, U. (1981) Natural ferrihydrites in surface deposits from Finland and their association with silica. Geochim. Cosmochim. Acta 45, 421–429.Google Scholar
Childs, C.W. (1992) Ferrihydrite: A review of structure, properties and occurrence in relation to soils. Z. Pflanze-nernähr. Bodenk. 155, 441–448.Google Scholar
Childs, C.W., Wells, N. & Downes, C.J. (1986) Kokowai Springs, Mount Egmont, New Zealand: chemistry and mineralogy of the ochre (ferrihydrite) deposit and analysis of the waters. J. Roy. Soc. New Zealand 16, 85–99.CrossRefGoogle Scholar
Cornell, R.M., Giovanoli, R. & Schindler, P.W. (1987) Effect of silicate species on the transformation of ferrihydrite into goethite and hematite in alkaline media. Clays Clay Miner. 35, 21–28.Google Scholar
Dzombak, D.A. & Morel, F.M.M. (1990) Surface Complexation Modeling. Hydrous Ferric: Oxide. J. Wiley & Sons, New York.Google Scholar
Fuller, C.C., Davis, J.A. & Waychunas, G.A. (1993) Surface chemistry of ferrihydrite: Part 2. Kinetics of arsenate adsorption and coprecipitation. Geochim. Cosmochim. Acta 57, 2271–2282.Google Scholar
Gastuche, M.C. (1964) The octahedral layer. ('lays Clay Miner. 12, 471–493.Google Scholar
Goldberg, S. (1985) Chemical modeling of anion competition on goethite using the constant capacitance model. Soil Sci. Soc. Am. J. 49, 851–856.Google Scholar
Grant, M. & Jordan, R.B. (1981) Kinetics of solvent water exchange on iron(Ill). lnorg. Chem. 20, 55–60.CrossRefGoogle Scholar
Goldberg, S. (1992) Use of surface complexation models in soil chemical systems. Adv. Agronomy 47, 233–329.Google Scholar
Hansen, H.C.B. (1992) TITRA-a MS Windows 3.x program for Communication between Metrohm pH-meters/ -autoburettes and a PC via RS-232. Tech. Rep., Chem. Dep., Royal Vet. & Agricultural Univ., Copenhagen (in Danish).Google Scholar
Hansen, H.C.B., Raben-Lange, B., Raulund-Rasmussen, K. & Borggaard, O.K. (1994) Monosilicate adsorption by ferrihydrite and goethite at pH 3-6. Soil Sci. (in press).Google Scholar
Herbillon, A.J. & Tran Vinh An, J. (1969) Heterogeneity in silicon-iron mixed hydroxides. J. Soil Sci. 20, 223–235.CrossRefGoogle Scholar
Lijklema, L. (1980) Interaction of orthophosphate with iron(Ill) and alnminium hydroxides. Environ. Sci. Tech. 41, 537–541.Google Scholar
Mcphaie, M., Page, A.L. & Bingham, F.T. (1972) Adsorption interactions of monosilicic and boric acid on hydrous oxides of iron and aluminium. Soil Sci. Soc. Amer. Proc. 36, 510–514.Google Scholar
Onoda, G.Y. Jr & De Bruyn, P.L. (1966) Proton adsorption at the ferric oxide/aqueous solution interface. I. A kinetic study of adsorption. Surf. Sci. 4, 48–63.CrossRefGoogle Scholar
Parfitt, R.L., Var Der Gaast, S.J. & Childs, C.W. (1992) A structural model for natural siliceous ferrihydrite. Clays Clay Miner. 40, 675–681.Google Scholar
Sauer, K.-H. & Keller, H. (1970) Zur photometrischen Bestimmung kleiner Siliciumgehalte. Arch. Eisenhiitten-wesen 41, 961–963.Google Scholar
Schwertmann, U. & Cornell, R.M. (1991) Iron Oxides in the Laboratory. Preparation and Characterization. VCH, Weinheim.Google Scholar
Schwertmann, U. & Fischer, W.R. (1973) Natural ‘amorp-hous’ ferric hydroxide. Geoderma 10, 237–247.CrossRefGoogle Scholar
Schwertmann, U. & Thalmann, H. (1976) The influence of [Fe(II)], [Si], and pH on the formation of lepidocrocite and ferrihydrite during oxidation of aqueous FeCl2 solutions. Clay Miner. 11, 189–199.CrossRefGoogle Scholar
Sigg, L. & Stumm, W. (1981) The interaction of anions and weak acids with the hydrous goethite (α-FeOOH) surface. Coll. Surf. 2, 101–107.Google Scholar
Tecator, (1984) Determination of Silica by Flow Injection Analysis. Application Short Note, ASTN 5/84.Google Scholar
Van Riemsdijk, W.H., Boumans, L.J.M. & De Haan, F.A,M. (1984) Phosphate sorption by soils. I. A diffusion-precipitation model for the reaction of phosphate with metal oxides in soil. Soil Sci. Soc. Am. J. 48, 537–541.Google Scholar
Vempati, R.K. & Loeppert, R.H. (1989) Influence of structural and adsorbed Si on the transformation of synthetic ferrihydrite. Clays Clay Miner. 37, 273–279.CrossRefGoogle Scholar
Westall, J.C. (1982) FITEQL. A Program for the Determination of Chemical Equilibrium Constants from Experimental Data. Users Guide, vet. 1.2. Report 82-01. Oregon State Univer., Corvallis, Oregon.Google Scholar
Westall, J. & Hohl, H. (1980) A comparison of electrostatic models for the oxide/solution interface. Adv. Coll. Interf. Sci. 12, 265–294.CrossRefGoogle Scholar
Westall, J.C. & Morel, F.M.M. (1977) FITEQL: A General Algorithm for the Determination of Metal-ligand Complex Stability Constants from Experimental Data. Technical Note 19, Ralph M. Parsons Laboratory, Department of Civil Engineering, Massachusetts Inst. Technology, Cambridge, Mass.Google Scholar
Westall, J.C., Zachary, J.L. & Morel, F.M.M. (1976) MINEQL: A Computer Program for the Calculation of Chemical Equilibrium Composition of Aqueous Systems, Technical Note 18, Ralph, M. Parsons Laboratory, Departments of Civil Engineering, Massachusetts Inst. of Technology, Cambridge, Mass.Google Scholar
Willett, I.R., Chartres, C. J. & Nguyen, T.T. (1988) Migration of phosphate into aggregated particles of ferrihydrite. J. Soil Sci. 39, 275–282.Google Scholar