Hydrotalcite and Hydrotalcite-Based Materials

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This chapter deals with the history of hydrotalcite and hydrotalcite-based materials. A rare mineral known as hydrotalcite was found in Sweden sometimes in the 1840s. Magnesium aluminum hydroxycarbonate, Mg6Al2 (OH)16CO34H2O, is its chemical name, and Taylor and Allmann independently determined its layered structure. For a long time, hydrotalcite and other isomorphous minerals (such as piroaurite, sjogrenite, and takovite) were the focus of most mineralogical studies. However, beginning in the 1970s, it was discovered that these rare minerals, also known as anionic clays, could be prepared quickly and affordably in a laboratory and have a variety of intriguing chemical properties. The different arrangements of the stacking of the layers, the ordering of the metal cations, as well as the arrangement of anions and water molecules in the interlayer galleries, result in a variety of stoichiometry in hydrotalcite, which are layered double hydroxides. Due to their unique characteristics, including their enormous surface area, ion exchangeability, insolubility in water, and most organic sorbents, among others, the compounds of the hydrotalcite group demonstrate a wide variety of potential uses.