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Mn 3 O 4 nanoparticles were synthesized from one-step reduction of KMnO 4 with glycerol at 80°C. The structural and surface morphological characterizations were carried out using FT-IR, XRD, and FESEM analyses. The elemental composition was evidenced from EDX analysis. XRD analysis showed the tetragonal crystal geometry of Mn 3 O 4 nanoparticles with an average crystallite size of ∼20 nm. The surface morphology of the Mn 3 O 4 nanoparticles was found to be spherical from the FESEM image. The Mn 3 O 4 nanoparticles were then tested as a potential oxidant for the decolorization of methylene blue (MB) and found to be capable of N-demethylation of MB forming thionine as the final product, and removing 80% of the dye in approximately 1 h. The decolorization of MB by Mn 3 O 4 occurred through a surface mechanism, i.e., formation of surface precursor complex between MB and surface-bound Mn (II, III), where, electron transfer occurs within the surface complex. The effect of suspension pH (3-4 < pH pzc ; 5-10 > pH pzc ) on MB decolorization was assessed. Suspension pH exerted double-edged effects on MB decolorization by influencing the formation of surface precursor complex, and reducing potential of the system.

Persuaded by the necessity of finding new sources of antibiotics, Ag NPs were synthesized by adopting a newly developed green synthesis technique and subsequently, their antibacterial activity against different pathogenic bacteria was evaluated.

The present study was carried out to determine the level of bioaccumulation of some heavy metals in a freshwater fish Ayre (Sperata aor Hamilton, 1822) The bioaccumulation of these four heavy metals in fish organs, sediment and water samples were also compared with FAO approved standard levels and other related studies, and found that the levels of bioaccumulation in the Dhaleshwari river exceeded all the standard levels.

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