Kinetics and equilibrium adsorption of copper(II) and nickel(II) ions from aqueous solution using sawdust xanthate modified with ethanediamine

Sawdust xanthate modified with ethanediamine was used for the removal of Cu(II) and Ni(II) from aqueous solution. The influence of various operating parameters such temperature and adsorbent dosage on the adsorption isotherms of modified sawdust was investigated. Thermodynamic parameters, namely Gibbs free energy (ΔGΘ), enthalpy (ΔHΘ) and entropy (ΔSΘ) of Cu(II) and Ni(II) adsorption process were calculated, showing that the adsorption is a spontaneous and exothermic process. The modified extended Langmuir equation approaches provide excellent prediction of the binary adsorption. In single and binary systems, the overall adsorption data were best described by the pseudo-second order kinetic model, then the calculated values of activation energy of Cu(II) and Ni(II) adsorption process were 59.12 and 55.92 kJ/mol respectively. The results show that the affinity of each metal ion onto the modified sawdust surface is influenced by the presence of the other one.