Removal of Nickel(II) from Aqueous Solutions Using Synthesized β-Zeolite and Its Ethylenediamine Derivative

β-Zeolite was synthesized and modified with ethylenediamine (EDA). The synthesized materials were characterized and used for the removal of nickel(II) from aqueous solutions. The influences of the pH, contact time, and temperature on nickel(II) adsorption onto synthesized β-zeolite and β-zeolite modified with ethylenediamine (β-zeolite–EDA) were studied by a batch technique, and X-ray photoelectron spectroscopy was employed to analyze the experimental data and identify the formation of coordination bonds between the adsorbents and nickel(II). The dynamic process showed that the adsorption of nickel(II) onto β-zeolite and β-zeolite–EDA matched the pseudo-second-order kinetics model, and the adsorption of nickel(II) was significantly dependent on the pH values. Through simulation of the adsorption isotherms by the Langmuir, Freundlich, and Dubinin–Radushkevich models, it could be seen that the adsorption patterns of nickel(II) onto β-zeolite and β-zeolite–EDA were mainly controlled by surface complexation and the adsorption processes were endothermic and spontaneous. The modification of β-zeolite–EDA improved the adsorption capacity of nickel(II) significantly; this shows a novel material for the removal of nickel(II) from the water environment for industrialized application.