Adsorption of Nickel (II) from Aqueous Solution Using Leucaena leucocephala Shells

Water pollution, as a result of industrial development, has detrimental effects on aquatic organisms and human beings. In this research, Leucaena leucocephala biomass was modified using Fenton’s reagent and sodium hydroxide, and the performances of the native, Fenton-treated, and NaOH-activated adsorbents for removal of Ni(II) from aqueous solution were evaluated under various experimental conditions such as initial pH, contact time, initial concentration of Ni(II), adsorbent dosage, and temperature. The adsorbents were characterized using Fourier transform infrared spectroscopy and pH of the point of zero charge. Kinetic and equilibrium adsorption data were well described by Elovich and Liu models, respectively. The maximum adsorption capacities are 50.66, 56.72, and 75.17 mg/g for the native, Fenton-treated, and NaOH-activated L. leucocephala adsorbents, respectively. Desorption of Ni(II) from the surface of the adsorbents was done effectively with 0.03 mol/L of hydrochloric acid. Thermodynamic calculations show that the adsorption process was spontaneous, feasible, and favorable because the values of ΔGo were negative. Adsorption of Ni(II) onto the adsorbents was exothermic (ΔHo values were negative) and there was also a decrease in the randomness of the liquid-solid interface (ΔGo values were negative). Overall, the three adsorbents can be used for the treatment of water that is contaminated with Ni(II).