Research Article
K. Kavitha, M. M. Senthamilsel
Abstract
The removal of divalent nickel from aqueous solutions on Acid Activated was studied at varying contact times, pH, initial divalent nickel concentrations, adsorbent dose and temperature. The adsorption followed second order kinetics and the rate is mainly controlled by intra-particle diffusion. Experimental equilibrium and kinetics data were fitted by Langmuir and Freundlich isotherms. The kinetics and thermodynamics of adsorption process were evaluated and the data followed pseudo kinetic model. The thermodynamic parameters for the present system including Gibbs free energy of adsorption ΔG°, changes in enthalpy of adsorption ΔH°, and changes in entropy of adsorption ΔS° were calculated using van't Hoff equation. Negative value of ΔG° suggests that adsorption is spontaneous. The positive value of ΔH° may suggest endothermic process of adsorption.