Coatings of Fe/Al Hydroxides Inhibited Acidification of Kaolinite and an Alfisol Subsoil Through Electrical Double-Layer Interaction and Physical Blocking

Abstract Variably charged soils confer a different pattern of soil chemical properties compared with a homogeneously charged colloidal system. The relative contents of soil mineralogical constituents and their interaction play important roles in the variation of charge characteristics and other chemical properties of the soils. In this study, coating and simple mixing of iron (Fe)/aluminum (Al) hydroxides with kaolinite and an Alfisol subsoil were made for comparative study of their effect on the electrochemical and acidity properties of kaolinite and Alfisol subsoil after electrodialysis. Transmission electron microscopy and X-ray diffraction analyses indicated that Fe hydroxide coating was more effective than their mixing in physically blocking the kaolinite surface and decreasing the peak intensity of XRD for kaolinite. Coated Fe hydroxides were also more effective than the mixed ones in shifting zeta potential in a positive value direction, decreasing effective cation exchange capacity, and inhibiting acidification of kaolinite and Alfisol subsoil, whereas there was little difference between coated and mixed amorphous aluminum hydroxide (Al(OH)3). The effect of coated Fe/Al hydroxides on effective cation exchange capacity of electrodialyzed kaolinite and Alfisol subsoil varied irreversibly with ionic strength of the bathing solutions. All the results demonstrated that coatings of Fe/Al hydroxides could decrease effective negative charge and inhibit acidification of kaolinite and Alfisol subsoil mainly through two mechanisms: diffuse double-layer overlapping between oppositely charged particles and physical blocking of kaolinite and Alfisol subsoil during electrodialysis. Therefore, Fe/Al hydroxides can act as antiacidification agents in variably charged soils.

[1]  R. Xu,et al.  Effect of Fe/Al Hydroxides on Desorption of K+ and NH+4 from Two Soils and Kaolinite , 2013 .

[2]  R. Xu,et al.  Inhibition of acidification of kaolinite and an Alfisol by aluminum oxides through electrical double‐layer interaction and coating , 2013 .

[3]  R. Xu,et al.  Inhibition of Acidification of Kaolinite and an Alfisol Subsoil by Iron Oxides Through Electrical Double-Layer Interaction , 2013 .

[4]  R. Xu,et al.  Iron oxides serve as natural anti-acidification agents in highly weathered soils , 2012, Journal of Soils and Sediments.

[5]  F. Liu,et al.  Microstructure, Interaction Mechanisms, and Stability of Binary Systems Containing Goethite and Kaolinite , 2012 .

[6]  R. Xu,et al.  Effect of Fe/Al oxides on desorption of Cd2+ from soils and minerals as related to diffuse layer overlapping , 2011 .

[7]  R. Xu,et al.  Effects of Amorphous Al(OH)3 on the Desorption of Ca2+, Mg2+, and Na+ from Soils and Minerals As Related to Diffuse Layer Overlapping , 2011 .

[8]  F. Anaissi,et al.  Iron oxyhydroxide nanostructured in montmorillonite clays: Preparation and characterization. , 2010, Journal of colloid and interface science.

[9]  Marek Kosmulski,et al.  pH-dependent surface charging and points of zero charge. IV. Update and new approach. , 2009, Journal of colloid and interface science.

[10]  A. Mockovčiaková,et al.  Structural study of bentonite/iron oxide composites , 2009 .

[11]  R. Xu,et al.  Electrical double layers' interaction between oppositely charged particles as related to surface charge density and ionic strength , 2008 .

[12]  D. Tiwari,et al.  Interaction between electrical double layers of soil colloids and Fe/Al oxides in suspensions. , 2007, Journal of colloid and interface science.

[13]  R. Xu,et al.  Interaction between electric double layers of kaolinite and Fe/Al oxides in suspensions , 2007 .

[14]  Marc Pansu,et al.  Handbook of Soil Analysis: Mineralogical, Organic and Inorganic Methods , 2006 .

[15]  U. Schwertmann,et al.  The Iron Oxides: Structure, Properties, Reactions, Occurrences and Uses , 2003 .

[16]  J. Zhuang,et al.  Effects of surface coatings on electrochemical properties and contaminant sorption of clay minerals. , 2002, Chemosphere.

[17]  Marek Kosmulski,et al.  The pH-dependent surface charging and the points of zero charge. , 2002, Journal of colloid and interface science.

[18]  L. West,et al.  Mineralogy and chemistry of some variable charge subsoils , 2000 .

[19]  Ioannou,et al.  Phosphate Adsorption on Hematite, Kaolinite, and Kaolinite-Hematite (k-h) Systems As Described by a Constant Capacitance Model , 1997, Journal of colloid and interface science.

[20]  B. Singh,et al.  Experimental Transformation of Kaolinite to Halloysite , 1996 .

[21]  F. Zhang,et al.  REACTIONS OF HYDROGEN IONS WITH VARIABLE CHARGE SOILS: I. MECHANISMS OF REACTION , 1991 .

[22]  K. Kyuma,et al.  Changes in zero point of charge (ZPC), specific surface area (SSA), and cation exchange capacity (CEC) of kaolinite and montmorillonite, and strongly weathered soils caused by Fe and Al coatings , 1990 .

[23]  S. Goldberg.  Interaction of aluminum and iron oxides and clay minerals and their effect on soil physical properties: A review , 1989 .

[24]  J. O. Reuss,et al.  Acid Deposition and the Acidification of Soils and Waters , 1986, Ecological Studies.

[25]  L. Lavkulich,et al.  Effect of sesquioxide coatings on surface charge of standard mineral and soil samples , 1983 .

[26]  P. Huang,et al.  RETENTION OF PHENOLIC ACIDS BY NONCRYSTALLINE HYDROXY‐ALUMINUM AND -IRON COMPOUNDS AND CLAY MINERALS OF SOILS , 1977 .

[27]  D. Greenland.  Charge characteristics of some kaolinite-iron hydroxide complexes , 1975 .

[28]  D. Jefferson,et al.  Electron-Microscopic and Mössbauer Spectroscopic Studies of Iron-Stained Kaolinite Minerals , 1975 .

[29]  D. Rowell,et al.  CHARGE DISTRIBUTION AND THE CATION EXCHANGE CAPACITY OF AN IRON‐RICH KAOLINITIC SOIL , 1972 .

[30]  J. L. McAtee,et al.  Mutual adsorption of clay minerals and colloidal hydrous aluminum oxide—an electron microscopy investigation , 1967 .

[31]  J. Quirk,et al.  Adsorption of potential-determining ions at the ferric oxide-aqueous electrolyte interface , 1967 .

[32]  E. Ranst,et al.  Variable Charge Soils: Their Mineralogy, Chemistry and Management , 2004 .

[33]  R. Naidu,et al.  Surface Charge and Solute Interactions in Soils , 1999 .

[34]  T. Yu.  Chemistry of Variable Charge Soils , 1997 .

[35]  H. Zhang.  Contribution of Iron and Aluminum Oxides to Electrokinetic Characteristics of Variable Charge Soils in Relation to Surface Charge , 1992 .

[36]  M. Sumner.  Effect of Iron Oxides on Positive and Negative Charges in Clays and Soils , 1963 .

[37]  M. L. Jackson,et al.  Chemical Weathering of Minerals in Soils , 1953 .