Preparation of anionic clay–birnessite manganese oxide composites by interlayer oxidation of oxalate ions by permanganate

Oxalate intercalated anionic clay-like nickel zinc hydroxysalt was obtained starting from nickel zinc hydroxyacetate, Ni3Zn2(OH)8(OAc)2·2H2O, by anion exchange. The intercalated oxalate species was reacted with potassium permanganate in such a way that the layered manganese oxide formed was within the interlayer region of the anionic clay resulting in a layered composite in which the negative charges on the birnessite type manganese oxide layers compensate the positive charges on the anionic clay layers. Birnessite to anionic clay ratio could be varied by varying the reaction time or the amount of potassium permanganate used.

Nickel zinc hydroxyoxalate was reacted with potassium permanganate to get nickel zinc hydroxide birnessite composites in which the positive charges on the hydroxide layers are neutralized by the negative charges on birnessite layers. Figure optionsDownload as PowerPoint slideHighlights
► Anionic and cationic layered solid composites prepared.
► Ni–Zn hydroxyoxalate reacted with KMnO4 to deposit MnO2 in the interlayer.
► Birnessite layers coexist with anionic clay layers in the composites.
► Birnessite/anionic clay ratio controlled by amount of KMnO4 used and reaction time