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In this study, silver nanoparticles was synthesized by a simple and ecofriendly method using plant gums of Araucaria heterophylla, Azadirachta indica and Prosopis chilensis. The biosynthesised silver nanoparticles were characterized by UV–visible spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive spectroscopy, Dynamic light scattering etc. Silver nanoparticles were tested for its antibacterial activity against Escherichia coli and Streptococcus sp. and anticancer activity against human breast cancer cell line (MCF 7) and also utilized for chromium removal. The particles were found to have antibacterial activity. [ABSTRACT FROM AUTHOR]

The present study attempted to analyze the biosorption behavior of novel biosorbent, Araucaria heterophylla (green plant) biomass, to remove Cd from solutions against various parameters, i.e., initial metal ion concentration, pH, temperature, sorbent dosage and biomass particle size. The maximum biosorption was found to be 90.02% at pH 5.5 and biosorption capacity ( q ) of Cd is 9.2506 mg g. The Langmuir and Freundlich equilibrium adsorption isotherms were studied and it was observed that Freundlich model is the best fit than the Langmuir model with correlation co-efficient of 0.999. Kinetic studies indicated that the biosorption process of Cd well followed the pseudo-second-order model with R 0.999. Thermodynamic studies observed that the process is exothermic (Δ H negative). Free energy change (Δ G ) with negative sign reflected the feasibility and spontaneous nature of the process. The chemical functional -OH groups, CH stretching vibrations, C=O carbonyl group of alcohol, C=O carbonyl group of amide, P=O stretching vibrations and -CH groups were involved in the biosorption process. The XRD pattern of the A. heterophylla was found to be mostly amorphous in nature. The SEM studies showed Cd biosorption on selective grains of the biosorbent. It was concluded that A. heterophylla leaf powder can be used as an effective, low-cost, and environmentally friendly biosorbent for the removal of Cd from aqueous solution. Graphical Abstract: [ABSTRACT FROM AUTHOR]

Background: In this paper, batch removal of hexavalent chromium from aqueous solutions by Araucaria heterophylla leaves was investigated. The batch experiments were conducted to study the adsorption of metal species and effect of different pH, contact time, metal concentration, biosorbent concentration, and adsorption capacity. Method: Freundlich and Langmuir's isotherm model were used to describe the adsorption behavior, and the experimental results fitted Freundlich model well. Results: The adsorption efficiency observed for all chromium concentrations, i.e., 1, 3, 5, and 10 mg/L was 100% and the equilibrium was achieved in 30 min for 1 and 3 mg/L, whereas for 5 and 10 mg/L, it was less than 60 min. FTIR spectra was taken to identify functional groups involved in the biosorption. Conclusion: Thus, Araucaria leaves can be considered as one of the cheap and efficient biosorbent for toxic hexavalent chromium removal from natural or wastewaters. [ABSTRACT FROM AUTHOR]