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Synthesis, Characterization and Application of Zero-Valent Silver nano Adsorbents

Siva Sundarajan, Sulaiman Muhammad Sameem , Sudharsan Sankaranarayanan, Sayeekannan Ramaraj

The main objective of this study is to synthesize silver nanoparticles via green approach (environmentally eco friendly method) without using hazardous compounds. Here we present the distinctive properties of the silver nanoparticles (AgNPs) synthesized using hot water Phyllanthus emblica leaf extract (PELE) a reducing and capping agent. The nature of AgNPs synthesized was analyzed by atomic force microscope (AFM), scanning electron microscope (SEM), energydispersive microanalysis (EDX), X-ray diffraction spectroscopy (XRD), flourier transform infra red (FTIR), thermo gravimetric analysis (TGA), differential thermal analysis (DTA) and UV–vis spectroscopy (UV). We explored the ability of the AgNPs for removing Hg2+ from aqueous solution. Moreover, adsorption isotherms, kinetics and thermodynamics were studied to understand the mechanism of the synthesized AgNPs adsorbing metal ions. The adsorption isotherms were well described by Langmuir isotherm model with correlating constant (R2) higher than 0.9945. The maximum adsorption capacity was determined at 303 K and was found to be 312 mg/g for Hg (II) ion respectively. The adsorption kinetics data were well fitted by the pseudo-second-order rate model with high regression coefficient (0.998). The intra particle diffusion of Hg (II) on AgNPs represents the rate-limiting step. The adsorption capacity was decreased with the increase of temperature, and thermodynamic calculations suggested that the adsorption of Hg (II) ions onto AgNPs is an exothermic process. It has been found that AgNPs show high selectivity‟s and adsorption capacities to removal of Hg2+ from its aqueous solution