Hydrotalcite synthesis via co-precipitation reactions using MgO and Al(OH)3 precursors

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.