Nickel (Ni) as a heavy metal due to its toxicity should be removed from wastewater and aquatic environments using efficient technology. The aim of this study was to remove Ni from an aqueous solution using palm leaf ash produced in a furnace. To do so, kinetic and thermodynamic experiments were conducted on the adsorption process. Moreover, the effect of time, pH, adsorbent and initial concentration of Ni was studied on Ni adsorption. The results of the experiment indicated that the Ni adsorption process followed the Freundlich isotherm model. The study of kinetic data also displayed the removal of Ni ions from the pseudo-second-order kinetics. The results showed that the percentage removal of Ni (II) and maximum adsorption capacity of an adsorbent for Ni (II) ions were 94.67% and 40.81 mgg-1, respectively. Furthermore, the enthalpy of the adsorption process (ΔH) was 62706.8 j.mol-1. Manuscript profile