Equilibrium and kinetic modelling of iron adsorption by eggshells in a batch system: effect of temperature

This paper aims to investigate the sorption of Fe(III) onto eggshells. In our experiments the batch sorption is studied with respect to solute concentration, contact time, adsorbent dose and temperature. The results show that the sorption capacity decreases with an increase in temperature from 20 to 50°C at the initial Fe(III) solution concentration of 5 mgl–1. Pseudo-second order model can be used to describe the kinetics of Fe(III) sorption. The constants obtained from the pseudo-second order kinetic model at different temperatures were evaluated and the activation energy was found to be –13.40 kJ/mol. Thermodynamic parameters such as enthalpy, entropy and Gibb's free energy changes were also calculated. The Freundlich and Langmuir adsorption models were applied to experimental equilibrium data and the isotherm constants were calculated using linear regression analysis.