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Hydrotalcite is a layered double hydroxide of general formula Mg₆Al₂CO₃(OH)₁₆·4(H₂O), whose name is derived from its resemblance with talc and its high water content. The layers of the structure may stack in different ways, to produce a 3-layer rhombohedral structure (3R Polytype), or a 2-layer hexagonal structure (2H polytype) which was formerly known under the name manasseite. The two polytypes are often intergrown.^[1]^[2]^[4] The carbonate anions that lie between the structural layers are weakly bound, so hydrotalcite has anion exchange capabilities.

It was first described in 1842 for an occurrence in a serpentine - magnesite deposit in Snarum, Modum, Buskerud, Norway.^[1] It occurs as an alteration mineral in serpentinite in association with serpentine, dolomite and hematite.^[2]

Hydrotalcite has been studied as potential getter for iodide in order to scavenge the long-lived ¹²⁹I (T_1/2 = 15.7 million years) and also other fission products such as ⁷⁹Se (T_1/2 = 295 000 years) and ⁹⁹Tc, (T_1/2 = 211 000 years) present in spent nuclear fuel to be disposed under oxidising conditions in volcanic tuff at the Yucca Mountain nuclear waste repository. Unfortunately carbonate easily replaces iodide in its interlayer. Another difficulty arising in the quest of an iodide getter for radioactive waste is the long-term stability of the sequestrant that must survive over geological time scales. Layered double hydroxides are well known for their anion exchange properties.

Hydrotalcite is also used as an antacid.

References

^ ^a ^b ^c Mindat.org
^ ^a ^b ^c Handbook of Mineralogy
^ Webmineral data
^ ^a ^b IMA Nomenclature Report

Jow, H. N.; R. C. Moore; K. B. Helean; S. Mattigod; M. Hochella; A. R. Felmy; J. Liu; K. Rosso; G. Fryxell; J. Krumhansl (2005). Yucca Mountain Project-Science & Technology Radionuclide Absorbers Development Program Overview. Yucca Mountain Project, Las Vegas, Nevada (US).

Jow, H. N.; R. C. Moore; K. B. Helean; J. Liu; J. Krumhansl; Y. Wang; S. Mattigod; A. R. Felmy; K. Rosso; G. Fryxell. "Radionuclide absorbers development program overview Office of Civilian Radioactive Waste Management (OCRWM), Science and Technology Program".

Kaufhold, S.; M. Pohlmann-Lortz; R. Dohrmann; R. Nüesch (2007). "About the possible upgrade of bentonite with respect to iodide retention capacity". Applied Clay Science 35 (1–2): 39–46. doi:10.1016/j.clay.2006.08.001.

Krumhansl, J. L.; P. Zhang; H. R. Westrich; C. R. Bryan; M. A. Molecke (2000). "Technetium getters in the near surface environment". Migration Conference 99.

Krumhansl, J. L.; J. D. Pless; J. B. Chwirka; K. C. Holt (2006). Yucca Mountain Project getter program results (Year 1) I-I29 and other anions of concern. SAND2006-3869, Yucca Mountain Project, Las Vegas, Nevada.

Mattigod, S. V.; G. E. Fryxell; R. J. Serne; K. E. Parker (2003). "Evaluation of novel getters for adsorption of radioiodine from groundwater and waste glass leachates". Radiochimica Acta 91 (9): 539–546. doi:10.1524/ract.91.9.539.20001.

Mattigod, S. V.; R. J. Serne; G. E. Fryxell (2003). Selection and testing of getters for adsorption of iodine-129 and technetium-99: a review. PNNL-14208, Pacific Northwest National Lab., Richland, WA (US).

Moore, R. C.; W. W. Lukens (2006). Workshop on development of radionuclide getters for the Yucca Mountain waste repository: proceedings. SAND2006-0947, Sandia National Laboratories.

Pless, J. D.; J. Benjamin Chwirka; J. L. Krumhansl (2007). "Iodine sequestration using delafossites and layered hydroxides". Environmental Chemistry Letters 5 (2): 85–89. doi:10.1007/s10311-006-0084-8.

Stucky, G.; H. M. Jennings; S. K. Hodson (1992). Engineered cementitious contaminant barriers and their method of manufacture. Google Patents.

English Journal

Protein interactions with nanosized hydrotalcites of different composition.

Bellezza F, Alberani A, Posati T, Tarpani L, Latterini L, Cipiciani A.AbstractNanosized hydrotalcite-like compounds (HTlc) with different chemical composition were prepared and used to study protein adsorption. Two soft proteins, myoglobin (Mb) and bovine serum albumin (BSA), were chosen to investigate the nature of the forces controlling the adsorption and how these depend on the chemical composition of the support. Both proteins strongly interact with HTlc exhibiting in most cases a Langmuir-type adsorption. Mb showed a higher affinity for Nickel Chromium (NiCr-HTlc) than for Nickel Aluminum (NiAl-HTlc), while for BSA no significant differences between supports were found. Adsorption experiments in the presence of additives showed that proteins exhibited different types of interactions onto the same HTlc surface and that the adsorption was strongly suppressed by the addition of disodium hydrogen phosphate (Na(2)HPO(4)). Atomic force microscopy images showed that the adsorption of both proteins onto nanoparticles was followed by the aggregation of biocomposites, with a more disordered structure for BSA. Fluorescence measurements for adsorbed Mb showed that the inorganic nanoparticles induced conformational changes in the biomolecules; in particular, the interactions with HTlc surface quenched the tryptophan fluorescence and this process was particularly efficient for NiCr-HTlc. The adsorption of BSA onto the HTlc nanoparticles induced a selective quenching of the exposed fluorescent residues, as indicated by the blue-shift of the emission spectra of tryptophan residues and by the shortening of the fluorescence decay times.
Journal of inorganic biochemistry.J Inorg Biochem.2012 Jan;106(1):134-42. Epub 2011 Oct 8.
Nanosized hydrotalcite-like compounds (HTlc) with different chemical composition were prepared and used to study protein adsorption. Two soft proteins, myoglobin (Mb) and bovine serum albumin (BSA), were chosen to investigate the nature of the forces controlling the adsorption and how these depend o
PMID 22115829

Molecular Modeling of Hydrotalcite Structure Intercalated with Transition Metal Oxide Anions: CrO(4)(2-) and VO(4)(3-).

Murthy V, Smith HD, Zhang H, Smith SC.SourceSchool of Environmental and Life Sciences, Charles Darwin University , Darwin, NT 0909, Australia.
The journal of physical chemistry. A.J Phys Chem A.2011 Nov 24;115(46):13673-83. Epub 2011 Oct 26.
Molecular dynamics (MD) simulations are used to study the interlayer structure, hydrogen bonding, and energetics of hydration of Mg/Al (2:1 and 4:1) layered double hydroxide (LDH) or hydrotalcite (HT) intercalated with oxymetal anions, CrO(4)(2-), and VO(4)(3-). The ab initio forcefield COMPASS is e
PMID 21970402

Japanese Journal

ハイドロタルサイトの"再水和"及び"層剥離"を利用する新規触媒の開発

触媒 57(6), 387-400, 2015-12
NAID 40020685121

ナノサイズ・ハイドロタルサイト様物質による低濃度フッ素含有排水の処理

Journal of the Society of Inorganic Materials, Japan : セッコウ・石灰・セメント・地球環境の科学 22(374), 47-51, 2015-01
NAID 40020312335

燃料電池用水素製造のための高分散担持Ni触媒の調製

Journal of the Japan Petroleum Institute 58(6), 353-364, 2015
NAID 130005117058

「ヒドロタルサイト」

Hydrotalcite
	Hydrotalcite with serpentine, Snarum, Modum, Buskerud, Norway. Size: 8.4 x 5.2 x 4.1 cm
General
Category	Carbonate mineral
Formula; (repeating unit)	Mg6Al2CO3(OH)16·4(H2O)
Strunz classification	05.DA.50
Crystal system	Trigonal
Unit cell	a = 3.065 Å, c = 23.07 Å; Z = 3/8;
Identification
Color	White with possible brownish tint
Crystal habit	Subhedral platey crystals, lamellar-fibrous, rarely euhedral prismatic; commonly foliated, massive
Crystal symmetry	(3R polytype) Trigonal hexagonal scalenohedral; H-M symbol: 32/m; Space group: R3m
Cleavage	{0001}, perfect
Tenacity	Flexible, not elastic
Mohs scale hardness	2
Luster	Satiny to greasy or waxy
Streak	White
Diaphaneity	Transparent
Specific gravity	2.03 - 2.09
Optical properties	Uniaxial (-)
Refractive index	nω = 1.511 - 1.531 nε = 1.495 - 1.529
Birefringence	δ = 0.016
Other characteristics	Greasy feel
References

　　[★]

英: hydrotalcite
商: サモール、ナシッド

[Mindat-1] Mindat.org

[Handbook-2] Handbook of Mineralogy

[Webmin-3] Webmineral data

[Report-4] IMA Nomenclature Report

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hydrotalcite

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