Acid activated clays: Materials in continuous demand

•An overview on the progress in research of acid activation of clays•Extensive parts on bentonites and methods of investigation•H+-exchanged clay minerals and why they appear rarely•Acid dissolution and properties of smectites and organo-smectites•Acid dissolution of non-swelling clay minerals

Acid activation is a chemical treatment traditionally used on clays, typically bentonites in hydrochloric or sulphuric acid, to obtain partly dissolved materials with enhanced surface properties suitable for new applications or displaying interesting new behaviour. This paper is based mostly on the results of long-running experiments in our laboratories, supplemented by published data from elsewhere. A review of recent literature shows that interest in these materials remains widespread, with several new developments of environmental relevance and in the area of clay-polymer nanocomposites. Acid treatment of vermiculites and of non-swelling clay materials is also included.

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