Removal of nickel from aqueous solutions using natural clay from northern morocco

Abstract

In the present study, natural Moroccan clay from the northern region was used to remove Ni(II) metal ions from model aqueous solutions. Batch adsorption studies were performed with various initial Ni(II) concentrations (from 40 to 200) mg/L, adsorbent dosages from 0,5 g to 7 g, pH, temperature and contact time. The adsorption capacity of Ni(II) increased with the initial concentration of metal ions, the contact time and the pH of the solution, but decreased with an increase in the amount of adsorbent. Overall, adsorption kinetics studies have shown that the nickel adsorption process follows pseudo-second order kinetics with a higher regression coefficient (R2=0,99). The equilibrium adsorption results are better adjusted with the Freundlich isotherm compared to the Langmuir models. The value of the separation factor, (RL=0,06) from the Langmuir equation and the Freundlich constant, (n = 3,3) both give an indication of favorable adsorption. Finally, from thermodynamic studies, the adsorption process was endothermic in nature due to the positive enthalpy ΔH°=107,38kjmol-1accompanied by a decrease in Gibbs free energy (ΔG°). In summary, Natural clay removed nickel with a maximum adsorption capacity of (1,407 mg/g, 300 K, pH = 4).