Separation of nickel(II) ions from synthetic aqueous solutions with novel dimethylglyoxime-modified Amberlite IRA-420: kinetic and equilibrium studies

In this study, the kinetic and equilibrium results obtained for Ni(II) ions sorption with different initial concentrations onto dimethylglyoxime-modified Amberlite IRA-420 (DMG-AMB) were analyzed. Fast equilibrium was reached after only 10 min where the removal percentage increased from around 60% to 90% with nickel(II) ions concentrations ranged from 3.0 to 15.0 mg/L. On the other hand, the capacity of the adsorbent increased linearly from 0.2 to 1.4 mg/g. The analysis of the kinetic data indicated that the sorption was a second-order process. An ion-exchange mechanism may have existed in the Ni(II) ions sorption process with DMG-AMB. The Ni(II) ions uptake by DMG-AMB quantitatively evaluated with equilibrium sorption isotherms. The maximum sorption capacity, determined from the Dubinin-Radushkevich (D-R) isotherm, was 15.067 mg/g. Moreover, diffusion mechanism of Ni(II) ions was described by different removal-diffusion models. The diffusion rate equations inside particulate of Dumwald-Wagner and intraparticle models were used to calculate the diffusion rate. The actual rate-controlling step involved in the Ni(II) ions sorption process was determined by the further analysis of sorption data by the kinetic expression given by Boyd.