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ABSTRACT
Nanocryptomelane and nanobirnessite were prepared in the presence and absence of nitrate and acetate ions. The prepared nanomaterials were characterized by powder X-ray diffraction (XRD) and scanning electron microscope (SEM) techniques. The cryptomelanes were predominantly of single phase. In both the cases powder XRD (PXRD) patterns indicated that the nitrate ion favored the reduction of the crystallinity. Oxidation of benzyl alcohol was studied with KMnO4 supported on the nanocryptomelane and nanobirnessite under green conditions. Oxidative ability was found to be a maximum for nanobirnessite (80.0%) prepared in the absence of nitrate and acetate ions. Commercially available pyrolusite support showed a poor conversion for the same period of time. Under solvent-free conditions, KMnO4 alone showed a yield of 39.0%. Cryptomelane supports, depending upon their history of separation, showed a marginal difference between them (55.1% and 50.2%). However, cryptomelane prepared in the absence of anions showed a conversion ability of 70.1%.