Adsorption of Pb(II), Cd(II) and Cu(II) Ions in Aqueous Solution on SWCNTs and SWCNT -COOH Surfaces: Kinetics Studies

摘要

The studies of kinetics and thermodynamics of adsorption of Pb(II), Cd(II) and Cu(II) ions in aqueous solutions on single-walled carbon nanotube (SWCNTs) and carboxylate group functionalized single-walled carbon nanotube (SWCNT-COOH) surfaces were by atomic absorption spectroscopy. The adsorption kinetics was well described by a pseudo-second-order rate model, while Langmuir, Freundlich, Redlich-Peterson (R-P) and Tempkin isotherms described the adsorption isotherms, and the adsorption thermodynamic parameters of equilibrium constant (K _0), standard free energy (ΔG~0), standard enthalpy (ΔH0) and standard entropy changes (ΔS~0) were measured. The adsorption of Pb(II), Cd(II) and Cu(II) ions from aqueous solutions on SWCNTs and SWCNT-COOH. The values of ΔH~0 and ΔG~0 suggested that the adsorption of mentioned ions on SWCNT-COOH and SWCNT were endothermic and spontaneous. The adsorption of mentioned ions on SWCNT-COOH is more than SWCNTs surfaces.