Kinetics and Thermodynamics of Lead ion Sorption on Carbon Nanotubes from Aqueous Solution

The kinetics and thermodynamics of lead ions sorption from aqueous solution on carbon nanotubes (CNTs) have been investigated. For this purpose, high-grade lead nitrate was used as heavy metal sample. The carbon nanotubes (CNTs) were used as adsorbents. In this work, adsorption rate was studied experimentally at various temperatures (283,298 and 303K), contact time, initial pH and initial lead concentration. It was observed that the lead adsorption rates increase dramatically in the initial times of experiment and reach equilibrium after 6 hr. The optimum pH was six. The experimental data was analyzed by Langmuir, Freundlich, Temkin and Redlich–Peterson isotherms using linear coefficient of determination. A batch sorption model, based on the assumption of the pseudo-second-order mechanism, was applied to predict the rate constant of sorption, the equilibrium sorption capacity and the initial sorption rate with the effect of temperature. Various thermodynamic parameters, ΔH°, ΔS° and ΔG°, were computed from equilibrium constant values. The results show that the sorption of the lead ions on CNTs is a spontaneous and endothermic nature process.

کلیدواژه ها:

Adsorption ، Isotherm ، Kinetic ، Carbon nanotubes ، Lead