Aluminate Chemistry in Aqueous Solutions

Aluminate chemistry in aqueous media centres on the behaviour of aluminium species under strongly alkaline conditions. In water at elevated pH, aluminium dissolves predominantly as the tetrahedral aluminate ion, [Al(OH)₄]⁻, which can undergo condensation and polymerisation to yield dimers, oligomers and, ultimately, crystalline hydroxide phases. Control of pH, temperature, ionic strength and the presence of carbonate or other anions dictates whether aluminium hydroxide precipitates as gibbsite, dawsonite or bayerite, each with distinct crystalline structures and industrial implications. Fundamental studies of speciation and coordination transformations, often employing in situ spectroscopic techniques, have revealed amorphous intermediates that mediate transition from solution to solid. These insights inform the optimisation of the Bayer process for alumina production, the design of tailored seeding strategies to regulate crystal size and morphology, and the development of sustainable routes for carbon capture via aluminate carbonation. Beyond metallurgy, aluminate solutions play roles in cement chemistry, water treatment and advanced materials synthesis, underscoring their global significance and multidisciplinary impact.

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Aluminate Chemistry in Aqueous Solutions publication trend

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Technical terms

Aluminate ion: Tetrahedrally coordinated anion [Al(OH)₄]⁻ prevalent in alkaline aluminium solutions.

Gibbsite: Crystalline aluminium hydroxide polymorph Al(OH)₃ formed upon cooling aluminate liquors.

Bayer process: Industrial method for extracting alumina from bauxite via caustic leaching and precipitation.

Seeding: Introduction of solid nuclei to control precipitation kinetics and particle morphology.

Amorphous phase: Non-crystalline solid intermediate lacking long-range atomic order.

MAS NMR: Magic Angle Spinning nuclear magnetic resonance for probing solid-state coordination environments.

References

1. Carbonation of Sodium Aluminate/Sodium Carbonate Solutions for Precipitation of Alumina Hydrates—Avoiding Dawsonite Formation. Crystals (2021).
2. Parameters Affecting the Precipitation of Al Phases from Aluminate Solutions of the Pedersen Process: The Effect of Carbonate Content. Journal of Sustainable Metallurgy (2021).
3. Enhanced Precipitation of Gibbsite from Sodium Aluminate Solution by Adding Agglomerated Active Al(OH)3 Seed. Metals (2023).
4. An amorphous sodium aluminate hydrate phase mediates aluminum coordination changes in highly alkaline sodium hydroxide solutions. Inorganic Chemistry Frontiers (2022).
5. Improving decomposition efficiency of aluminate liquor through preparation and introduction of active seed during the decomposition process. iPolytech Journal (2023).