Abstract
Chemical modifications of various clay minerals from the smectite group are discussed. Acid activation, i.e., partial dissolution of smectites in inorganic acids, is a common treatment applied to produce laboratory samples as well as industrial materials, such as adsorbents, catalysts, etc. The reaction product of an acid dissolution of a clay is independent on the starting mineral used. It is a hydrous amorphous partly protonated high surface silica phase. Proton-saturated smectites, prepared either via mild acid treatment or using ion-exchangers, are unstable materials undergoing autotransformation to their (H,Al,Fe,Mg)-forms. Mildly acid-treated montmorillonites exhibit a high catalytic activity. Acid treatment of tetraalkylammonium cation exchanged smectites produces hybrid catalysts of increased catalytic activity because of the enhanced hydrophobicity of the organoclay. Acid attack of the clay structure occurs not only from the particle edges but also from the interlayers.
The negative charge of the layers, arising from the partial non-equivalent substitution of the central atoms in the octahedral and/or tetrahedral sheets, is the most important feature of smectites. It can be chemically increased via structural FeIII reduction or decreased via Li+ fixation. Reduction of structural FeIII to FeII in smectites affects many properties of the clay. Over 90% of structural FeIII in smectites can be chemically reduced. The reduced clays are unstable and undergo reoxidation on air. Another method for modifying the layer charge and thus the properties of dioctahedral smectites is to heat the clay in the presence of Li+, causing the small Li+ ions to enter into the 2:1 layer structure, which decreases the layer charge. A partial stabilisation of FeII in chemically reduced smectites can be achieved via Li-saturation and heating of the reduced clay in an inert atmosphere.
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References
Siddiqui M.H.K., Bleaching Earths, Pergamon Press, London (1968).
Brown D.R., Clays as catalyst and reagent supports, Geologica Carpathica Ser. Clays 45, 45–56 (1994).
Fahn R. and Fenderl K., Reaction products of organic dye molecules with acid-treated montmorillonite, Clay Miner. 18, 447–458 (1983).
Stucki J.W, “Structural iron in smectites”, in J.W. Stucki, B.A. Goodman and U. Schwertmann (Eds.), Iron in Soils and Clay Minerals, Reidel, Dordrecht, pp. 625–675 (1988).
Hofmann U. and Kiemen R., Verlust der Austauschfähigkeit von Lithiuminonen an Bentonit durch Erhitzung, Z. Anorg. Allg. Chem. 262, 95–99 (1950).
Calvet R. and Prost R., Cation migration into empty octahedral sites and surface properties of clays, Clays Clay Miner. 19, 175–186 (1971).
Bujdák J., Slosiariková H., Nováková L. and Čičel B., Fixation of lithium cations in montmorillonite, Chem. Papers 45, 499–507 (1991).
Greene-Kelly R., The identification of montmorillonoids in clays, J. Soil Sci. 4, 233–237 (1953).
Alvero R., Alba M.D., Castro M.A. and Trillo J.M., Reversible migration of lithium in montmorillonite, J. Phys. Chem. 98, 7848–7853 (1994).
Komadel P., Madejová J. and Stucki J.W., Partial stabilization of Fe(II) in ferruginous smectite by Lifixation, Clays Clay Miner. (in press, 1998).
Kaplan H., “One step process of acid activating mineral clays and alkylating phenolic compounds with an alkene hydrocarbon”, U.S. Patent 3287422 (1966).
Čičel B., Komadel P. and Nigrin M., Catalytic activity of smectites on dimerization of oleic acid, Coll. Czech. Chem. Commun. 57, 1666–1671 (1992).
Adams J.M., Synthetic organic chemistry using pillared, cation-exchanged and acid-treated montmorillonite catalysts — A review, Appl. Clay Sci. 2, 309–342 (1987).
Clark J.H., Cullen S.R., Barlow S.J. and Bastok T.W., Environmentally friendly chemistry using supported reagent catalysts: Structure-property relationships for Clayzic, J. Chem. Soc. Perkin Trans. 2, 1117–1130 (1994).
Figueras F., Pillared clays as catalysts, Catal. Rev., Sci. Eng. 30, 457–499 (1988).
Mokaya R. and Jones W., Pillared acid-activated clay catalysts, J. Chem. Soc. Chem. Commun., 929–930(1994).
Bovey J. and Jones W., Characterisation of Al-pillared acid-activated clay catalysts, J. Mater. Chem. 4, 2027–2035 (1996).
Bovey J., Kooli F. and Jones W., Preparation and characterization of Ti-pillared acid-activated clay catalyst, Clay Miner. 31, 501–506 (1996).
Mokaya R., Jones W., Davies W. and Whittle M.E., Preparation of alumina-pillared acid-activated clays and their use as chlorophyll adsorbents, J. Mater. Chem. 3, 381–387 (1993).
Breen C., Zahoor F.D., Madejová J. and Komadel P., Characterisation and catalytic activity of acid treated, size fractionated smectites, J. Phys. Chem. B 101, 5324–5331 (1997).
Vincente Rodríguez M. A., Suárez Barrios M., López-González J.D. and Bañares-Muñoz M.A., Acid activation of a ferrous saponite (griffithite): Physicochemical characterization and surface area of the products obtained, Clays Clay Miner. 42, 724–730 (1994).
Komadel P., Madejová J., Janek M., Gates W.P., Kirkpatrick R.J. and Stucki J.W., Dissolution of hectorite in inorganic acids, Clays Clay Miner. 44, 228–236 (1996).
Novák I. and Čičel B., Dissolution of smectites in hydrochloric acid: II. Dissolution rate as a function of crystallochemical composition, Clays Clay Miner. 26, 341–344 (1978).
Breen C., Madejová J. and Komadel P., Characterisation of moderately acid-treated, size-fractionated montmorillonites using IR and MAS NMR spectroscopy and thermal analysis, J. Mater. Chem. 5, 469–474 (1995).
Breen C., Madejová J. and Komadel P., Correlation of catalytic activity with infrared-red, 29Si MAS NMR and acidity data for HCl-treated fine fractions of montmorillonites, Appl. Clay Sci. 10, 219–230 (1995).
Breen C., Zahoor F.D., Madejová J., Komadel P., Characterisation and catalytic activity of acid treated, size fractionated smectites, J. Phys. Chem. B 101, 5324–5331 (1997).
Komadel P., Janek M., Madejová J., Weekes A. and Breen C., Acidity and catalytic activity of mildly acid-treated Mg-rich montmorillonite and hectorite, J. Chem. Soc., Faraday Trans. 93, 4207–4210 (1997).
Čičel B. and Komadel P., “Structural formulae of layer silicates”, in J.E. Amonette and L.W. Zelazny (Eds.), Quantitative Methods in Soil Mineralogy, Soil Science Society of America, Madison, WI, pp. 114–136 (1994).
Komadel P., Stucki J.W., Čičel B., Readily HCl-soluble iron in the fine fractions of some Czech bentonites, Geologica Carpathica, Ser. Clays 44, 11–16 (1993).
Barshad I., Preparation of H-saturated montmorillonites, Soil Sci. 108, 38–42 (1969).
Barshad I. and Foscolos A.E., Factors affecting the rate of the interchange reaction of adsorbed H+ on the 2:1 clay minerals, Soil Sci. 110, 52–60 (1970).
Janek M. and Komadel P., Autotransformation of H-smectites in aqueous solution: The effect of octahedral cation content. Geologica Carpathica, Ser. Clays 44, 59–64 (1993).
Janek M., Komadel P. and Lagaly G., Effect of autotransformation on the layer charge of smectites determined by alkylammonium method, Clay Miner. 32, 623–632 (1997).
Rhodes C.N. and Brown D.R., Catalytic activity of acid-treated montmorillonite in polar and nonpolar reaction media, Catal. Lett. 24, 285–291 (1994).
Breen C., Watson R., Madejová J., Komadel P. and Klapyta Z., Acid-activated organoclays: Preparation, characterisation and catalytic activity of acid-treated tetra-alkylammonium exchanged smectites, Langmuir 13, 6473–6479 (1997).
Breen C. and Watson R., Acid-activated organoclays: preparation, characterisation and catalytic activity of polycation-treated bentonites, Appl. Clay Sci. 12, 479–494 (1998).
Komadel P., Lear P.R. and Stucki J.W., Reduction and reoxidation of nontronite: Extent of reduction and reaction rates, Clays Clay Miner. 38, 203–208 (1990).
Komadel P., Madejová J. and Stucki J.W., Reduction and reoxidation of nontronite: Questions of reversibility, Clays Clay Miner. 43, 105–110 (1995).
Bujdák J., Petrovičová I. and Slosiariková H., Study of water-reduced charge montmorillonite system, Geologica Carpathica, Ser. Clays 43, 109–111 (1992).
Madejová J., Bujdák J., Gates W.P and Komadel P., Preparation and infrared spectroscopic characterization of reduced-charge montmorillonite with various Li contents, Clay Miner. 31, 233–241 (1996).
Komadel P., Bujdák J., Madejová J., Šucha V. and Elsass F., Effect of non-swelling layers on the dissolution of reduced-charge montmorillonite in hydrochloric acid, Clay Miner. 31, 333–345 (1996).
Bujdák J. and Komadel P., Interaction of methylene blue with reduced charge montmorillonite, J. Phys. Chem. B 101, 9065–9068 (1997).
Madejová J., Arvaiová B. and Komadel P., FTIR spectroscopic characterization of thermally treated Cu2+, Cd2+, and Li+ montmorillonites, Spectrochimica Acta A (submitted, 1998).
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Komadel, P. (1999). Structure and Chemical Characteristics of Modified Clays. In: Misaelides, P., Macášek, F., Pinnavaia, T.J., Colella, C. (eds) Natural Microporous Materials in Environmental Technology. NATO Science Series, vol 362. Springer, Dordrecht. https://doi.org/10.1007/978-94-011-4499-5_1
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DOI: https://doi.org/10.1007/978-94-011-4499-5_1
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