Effect of calcination temperature on morphology and phase transformation of MnO2 nanoparticles: A step towards green synthesis for reactive dye adsorption.

Green synthesis of manganese oxide nanoparticles (NPs) was carried out by sol-gel method using Acacia Concinna fruit extract for removal of reactive dye. The effect of calcination temperature on its morphology was investigated. α-MnO2 and Mn3O4 NPs were synthesized at 400 °C and 900 °C respectively and were characterized by PXRD, SEM, TEM, FTIR, BET, Raman and TGA. As-synthesized MnO2 NPs were investigated for the adsorption of Reactive Blue 21 (RB-21) dye. The effect of pH, adsorbent dose, agitation speed, initial dye concentration and temperature on dye removal was explored. pHpzc was calculated from zeta potential study showing positive surface charge below pH 3.18 resulting in electrostatic force of attraction between adsorbate and adsorbent. Both linear and non-linear regression approaches were utilised for the fitting of kinetic models and adsorption isotherms. Adsorption data follows a pseudo second order kinetics and fits well with the Freundlich isotherm model. Thermodynamic parameters such as ΔHo, ΔSo and ΔGo were determined. The dye removal efficiency, in case of MnO2 NPs at pH 3.0 was obtained to be 98% whereas for Mn3O4, no such dye adsorption was observed. The mechanism of adsorption was studied theoretically confirming π-π interaction and H-bonding between the MnO2 and RB dye molecules.

Sustainable and Efficient Route for the Regeneration of Carbonyl Compounds from Oximes Using Aqueous Extract of Sapindus laurifolia under Microwave Radiation.

The synthesis of organic compounds using aqueous medium has become an indispensable tool for modern chemical synthesis strategies because of its ability to produce pure products with higher yield at ambient temperature. The conversion of oxime group into carbonyl group serves as a key step for several organic syntheses. This article describes the regeneration of carbonyl compounds from the oxime group present in various carbon skeletons using I2 and aqueous extract of Sapindus laurifolia under microwave radiation. A correlation has been established between the critical micellar concentration of saponin extracted from Sapindous laurifolia and the yield percentage of regenerated different carbonyl compounds. An effortless, competent, and environmentally compassionate protocol for the regeneration of carbonyl compound with a high percent of yield in the range 45-95% could be achieved.

Therapeutic prospective of plant-induced silver nanoparticles: application as antimicrobial and anticancer agent.

Green synthesis approach for nanoparticle is environmental friendly, non-hazardous and the nanoparticles have shown enhanced biocompatibility for application in healthcare. Previous reviews have mentioned about green synthesis methods for nanoparticles and their biological activities. This review not only covers the general information about green synthesis of silver nanoparticles and characterization, but also focused on recent uses of various medicinal and nonmedical plants based AgNPs synthesis and their broad-spectrum antimicrobial and anticancer activities. In addition, this review emphasizes on elaborating underlying mechanism of anti-pathogenic microbial and anticancer activities of plant based AgNPs. Thus, present article provides a comprehensive analysis of plant-mediated synthesis of AgNPs and their potential applications in biomedical field including their mode of action and challenges in a single window.