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The equilibrium and thermodynamics of Pb(II), Cd(II) and Cu(II) ions adsorption from aqueous solution onto single-walled carbon nanotube (SWCNT) and carboxylate group functionalized single-walled carbon nanotube (SWCNT-COOH) surfaces were studied by atomic absorption spectroscopy. The effect of contact time, pH, initial concentration of ion, ionic strength and temperature on the adsorption of ion was investigated. The results indicated that Langmuir model fits adsorption isotherm data better than the Freundlich model. The results also demonstrated that SWCNT-COOH surfaces can more effectively adsorb mentioned ions than a SWCNT surface. Maximum adsorption capacities (q m ) for Pb(II), Cu(II) and Cd(II) ions onto SWCNT-COOH were obtained as 96.02, 77.00 and 55.89 mg/g, respectively, and by SWCNTs as 33.55, 24.29 and 24.07 mg/g, respectively. Thermodynamic parameters values showed that the adsorption of ions on SWCNT-COOH and SWCNTs at 283-313 K is spontaneous and endothermic.

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Developing low cost and environmentally friendly methods for metallic nanoparticles is an increasing need. Using plants towards synthesis of nanoparticles are beneficial with the presence of bio-molecules in plants, which can act as capping/stabilizing and reducing agents. In the present attempt, we describe rapid biosynthesis of silver nanoparticles by Satureja intermedia C. A. Mey (Lamiaceae) aqueous extract. Synthesized nanoparticles were characterized by UV-Visible spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM) and the chemical groups in plant extract were detected by Fourier Transform Infra-Red (FT-IR) spectroscopy. The XRD study showed crystalline nature and face cubic center shape for nanoparticles. TEM study showed that the mean diameter and standard deviation for the silver nanoparticles were 29.29 ± 28.18 nm. Total phenolic and flavonoid contents and radical scavenging activity of the aqueous extract and SNPs/extract mixture, were also evaluated in this study. It can be concluded that the aerial parts of S. intermedia is a good source of phenolic compounds, a potent antioxidant and a valuable choice for bio-reduction and biosynthesis of silver nanoparticles.