Abstract—A new adsorbent material for removing lead ions from aqueous solutions has been investigated. Present study deals with the sorption of Pb(II) from aqueous solution on chemically pretreated rice husk. Batch kinetic studies were conducted for the adsorption of Pb(II) on NCRH (sodium carbonate treated rice husk). At the adsorbent dose of 10 g/l and initial Pb(II) concentration of 10 mg/l, 96 to 98.5 % removal were observed when the temperature increases from 15° to 50° C. Equilibrium time was found to be 60 min. This paper attempts to develop simple and easily understandable thermodynamic parameters related sorption process at the equilibrium. The overall scenario represented by thermodynamic parameters was found to be a better indicator of understanding the process mechanism. Sorption of Pb(II) on NCRH followed pseudo second-order kinetic equation. The Gibbs free energy ΔGo values for the adsorption processes of Pb(II) at 15°, 30°, 40° and 50o C was obtained as – 7.55, – 9.80, – 10.41 and – 11.06, kJ/mol respectively. The negative value, ΔG° confirms the feasibility of the adsorption process and spontaneous nature of adsorption. The values of ΔH° and ΔS° for Pb(II) were obtained as 21.31 kJ/mol and 101.11 J/mol respectively. The positive value of ΔH° indicates endothermic nature of adsorption, while positive ΔS° value confirms the increased randomness at the solid-liquid interface during adsorption. The activation energy for the sorption of Pb(II), was found as 20.02 kJ/mol indicating chemisorptions.
Index Terms—Activation energy, Gibbs free energy, NCRH,lead, thermodynamics, sorption.
Upendra Kumar is with the Department of Civil Engineering, National Institute of Technology, Silchar, Assam, India (phone: +91-94351-76340; (e-mail: upendra_kumar72@rediffmail.com).
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Cite: Upendra Kumar and Jyotikusum Acharya, "Thermodynamics of the Sorption of Pb(II) from Aqueous Solution on NCRH," International Journal of Chemical Engineering and Applications vol. 2, no. 6, pp. 416-420, 2011.
