Synthesis and characterisation of hydrotalcites produced by an aluminium hazardous waste: A comparison between the use of ammonia and the use of triethanolamine

• High quality Mg/A hydrotalcite-like compounds were prepared from an aluminium hazardous waste.
• Co-precipitation reactions with NH3 and TEA
• Clear changes in textural, morphologic and spectroscopic properties
• Ammonia co-precipitation allowed the entry of iron impurities.
• TEA co-precipitation purified the products coming from the waste.

Hydrotalcite-like compounds were co-precipitated with diluted sodium hydroxide from an unconventional aluminium source: the aluminium waste generated by the tertiary aluminium industry, with the assistance of ammonia and triethanolamine at pH 10. These products were characterised by several techniques (XRD, FT-IR, UV–vis-NIR, SEM, DTA-TG and BET methods) to compare results. The characterisation of products confirmed significant differences depending on basic reagent selected. Products co-precipitated with ammonia showed less crystal growth, a more significant iron content in the structure and higher internal surface area. Products from triethanolamine showed the entry of organic molecules into the layered structure. These findings were important for the improvement of methods based on waste treatment, transforming an aluminium hazardous waste into a value added product as layered double hydroxides.

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