The Removal of Ions by Functionalized Carbon Nanotube: Equilibrium, Isotherms and Thermodynamic Studies

O. Moradi

Abstract
In this studies removal of some ions such as Pb(II), Cd(II) and Cu(II) by single walled carbon nanotubes (SWCNTs) and carboxylate functionalized (SWCNTs-COOH) from aqueous solution were studied. The effect of pH, contact time, initial concentration, ionic strength, temperature, equilibrium, models and thermodynamic parameters on the removal of ions was investigated. The results indicated that Langmuir fits adsorption isotherm data better than Freundlich model. The results also demonstrated that SWCNTs-COOH can remove ions more effectively. Maximum adsorption capacities for Pb(II), Cu(II) and Cd(II) ions on SWCNTs-COOH were obtained as 96.02, 77.00 and 55.89 mg g–1, respectively and by SWCNTs, as 33.55, 24.29 and 24.07 mg g–1, respectively. Thermodynamic parameters values showed that the adsorption of ions on SWCNTs-COOH and SWCNTs at 283–313 K are spontaneous and endothermic. Further, adsorption of ions by SWCNTs-COOH and SWCNTs are chemisorption and physisorption processes, respectively.

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Keywords
Heavy metal ions, adsorption, functionalized single-walled nanotubes (SWCNTs-COOH), isotherm models, thermodynamic functions