Determination of kinetic and thermodynamic parameters of heavy metal removal from aqueous solution by nano zero valent iron (NZVI) and nano copper oxide (nCuO)

In order to study the equilibrium, kinetic and thermodynamic of cadmium (Cd), lead (Pb), copper (Cu) and zinc (Zn) adsorption by nano zero valent iron (nZVI) and nano copper oxide (nCuO), batch experiments carried out with different initial concentration of the metals at different time and temperature. The results showed that the removal efficiency and adsorption capacity of nano particles increased with increasing initial concentration. Among adsorption kinetic models, pseudo second order model was better fitted for experimental data (R2=0.99-1.00). The adsorption data were well fitted with Langmuir model compared to Freundlich, Temkin and Dubinin-Radushkevich models. Maximum mono layer adsorption (qmax) of Cd, Pb, Cu and Zn were obtained 218, 239, 242 and 215 mg g-1 for nano zero valent iron and 90, 176, 100 and 76 for nano copper oxide respectively. The sorption energy parameter (E) of Dubinin-Radushkevich isotherm and Gibbs free energy change (ΔG) indicated that the metals adsorption processes were physical and spontaneous. The separation factor of Langmuir (RL) indicated that the sorption reactions of metals by the nano particles is favorable (RL=0.03-0.50).