Separation of La(III) and Ni(II) from Binary System Using Manganese Oxide Nanorods

The recovery and separation of lanthanum from a La(III)/Ni(II) mixture present a significant challenge in obtaining high-purity lanthanum, which is necessary for many applications in various industries. In the present study, manganese oxide nanorods were prepared and characterized by TEM, EDX, SEM, FT-IR, TGA, and XRD. The TEM images reported that the manganese oxide nanoparticles were arranged into rod-shaped structures with pores between them. Batch adsorption experiments were performed to evaluate the sorption efficiency and separation of La(III) and Ni(II) from the binary system under varying conditions, including shaking time, solution pH, initial metal ion concentration, adsorbent dosage, and temperature. The results obtained showed that the sorption process of La(III) and Ni(II) using MnO₂-nanorods fit well with the pseudo-second-order kinetics and the Langmuir isotherm model. The experimental sorption capacities according to the Langmuir isotherm model were found to be 13.757 mg/g and 0.766 mg/g for La(III) and Ni(II), respectively. According to thermodynamic results, the sorption process for Ni(II) and La(III) was endothermic and spontaneous was verified by the positive ΔH^o and the negative ΔG^o values. Furthermore, the MnO₂-nanorods presented excellent selectivity and separation of lanthanum from the La(III)/Ni(II) mixture at pH 3.0, shaking time 30.0 min, and 0.05 adsorbent dosage at room temperature.