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Tên bài: Ceramics International
Volume 37, Issue 8, December 2011, Pages 3063-3070
Tác giả: Rafael Salomãoa, , , L.M. Milenaa, M.H. Wakamatsua, Victor C. Pandolfellib,



Hydrotalcitesynthesis via co-precipitation reactions using MgO and Al(OH)3 precursors
Rafael Salomãoa, , , L.M. Milenaa, M.H. Wakamatsua, Victor C. Pandolfellib,


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a Federal University of the ABC Region, Rua Santa Adélia, 166 ZIP 09210-170, Santo André, SP, Brazil
b Federal University of São Carlos – Materials Engineering Department, Rodovia Washington Luís, km 235, São Carlos, SP, Brazil
Received 22 March 2011; revised 5 May 2011; Accepted 9 May 2011. Available online 13 May 2011.

Abstract
Hydrotalcite (Mg6Al2(OH)16(CO3)·4H2O), also known as aluminum–magnesium layered double hydroxide (LDH) or anionic clay, is a synthetic compound that was broadly investigated in the past decade due to its many potential applications, such as clinic anti-acid, catalyst support, adsorptive flotation, flame retardant, acid scavengers in polymer composites and as a raw material for high temperature insulating porous ceramics. This compound is usually produced by controlled chemical equilibrium shifting processes (such as co-precipitation) that requires various other purification steps (centrifugation, for example) and careful drying (freeze drying or ultrafiltration). In this paper, a novel route to synthesize hydrotalcite is presented, based on the hydration, dissolution and co-precipitation reactions carried out almost simultaneously in aqueous suspension containing reactive magnesium oxide and aluminum hydroxide. Compared to other methods (the regular co-precipitation, particularly), it presents various technological advantages such as low time-energy consumption, no further purification step requirement, high output and competitive production costs.

Keywords: Hydrotalcite; Magnesium oxide; Aluminum hydroxide; Hydration

Article Outline
1. Introduction
2. Materials and techniques
3. Results and discussion
3.1. Aqueous mixing of different sources of Mg2+ and Al3+ ions
3.2. The MgO–Al(OH)3 system
4. Remarks
Acknowledgements
References