Phosphate-intercalated Ca-Fe-layered double hydroxides: Crystal structure, bonding character, and release kinetics of phosphate

Journal Article · Sat Jan 15 00:00:00 EST 2011 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2010.11.003· OSTI ID:21494184

Woo, Myong A; Woo Kim, Tae; Paek, Mi-Jeong; Ha, Hyung-Wook; Choy, Jin-Ho ^[1]; Hwang, Seong-Ju ^[1]

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1. Center for Intelligent Nano-Bio Materials (CINBM), Department of Chemistry and Nano Sciences, Ewha Womans University, Seoul 120-750 (Korea, Republic of)

The nitrate-form of Ca-Fe-layered double hydroxide (Ca-Fe-LDH) was synthesized via co-precipitation method, and its phosphate-intercalates were prepared by ion-exchange reaction. According to X-ray diffraction analysis, the Ca-Fe-LDH-NO{sub 3}{sup -} compound and its H{sub 2}PO{sub 4}{sup -}-intercalate showed hexagonal layered structures, whereas the ion-exchange reaction with HPO{sub 4}{sup 2-} caused a frustration of the layer ordering of LDH. Fe K-edge X-ray absorption spectroscopy clearly demonstrated that the Ca-Fe-LDH lattice with trivalent iron ions was well-maintained after the ion-exchange with HPO{sub 4}{sup 2-} and H{sub 2}PO{sub 4}{sup -}. Under acidic conditions, phosphate ions were slowly released from the Ca-Fe-LDH lattice and the simultaneous release of hydroxide caused the neutralization of acidic media. Fitting analysis based on kinetic models indicated a heterogeneous diffusion process of phosphates and a distinct dependence of release rate on the charge of phosphates. This study strongly suggested that Ca-Fe-LDH is applicable as bifunctional vector for slow release of phosphate fertilizer and for the neutralization of acid soil. -- Graphical abstract: We synthesized phosphate-intercalated Ca-Fe-LDH materials that can act as bifunctional inorganic vectors for the slow release of phosphate fertilizer and also the neutralization of acid soil. Fitting analysis based on kinetic models indicated a heterogeneous diffusion process of phosphates and a distinct dependence of release rate on the charge of phosphates. Display Omitted Research Highlights: {yields} The phosphate forms of Ca-Fe-layered double hydroxide (Ca-Fe-LDH) were synthesized via co-precipitation method. The crystal structure, bonding character, and release kinetics of phosphate of the phosphate-intercalates were investigated. These Ca-Fe-LDH materials are applicable as bifunctional vector for slow release of phosphate fertilizer and for the neutralization of acid soil.

• OSTI ID: 21494184
• Journal Information: Journal of Solid State Chemistry, Vol. 184, Issue 1; Other Information: DOI: 10.1016/j.jssc.2010.11.003; PII: S0022-4596(10)00509-8; Copyright (c) 2010 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ABSORPTION SPECTROSCOPY
CALCIUM HYDROXIDES
CLATHRATES
COPRECIPITATION
CRYSTAL STRUCTURE
DIFFUSION
FERTILIZERS
ION EXCHANGE
IRON HYDROXIDES
IRON IONS
KINETICS
NITRATES
PHOSPHATES
PHOSPHORIC ACID
VECTORS
X-RAY DIFFRACTION
X-RAY SPECTROSCOPY
ALKALINE EARTH METAL COMPOUNDS
CALCIUM COMPOUNDS
CHARGED PARTICLES
COHERENT SCATTERING
DIFFRACTION
HYDROGEN COMPOUNDS
HYDROXIDES
INORGANIC ACIDS
INORGANIC COMPOUNDS
IONS
IRON COMPOUNDS
NITROGEN COMPOUNDS
OXYGEN COMPOUNDS
PHOSPHORUS COMPOUNDS
PRECIPITATION
SCATTERING
SEPARATION PROCESSES
SPECTROSCOPY
TENSORS
TRANSITION ELEMENT COMPOUNDS