Evaluation of possible use of the macroporous ion exchanger in the adsorption process of rare earth elements and heavy metal ions from spent batteries solutions

In the paper Purolite S957 was used to determine the most effective conditions for the separation of La(III) and Ni(II) ions from acidic solutions. Preliminary studies of the sorption of La(III), Ce(III), Nd(III), Fe(III), Ni(II), Co (II), Cu(II) and Zn(II) mixture were carried out. The sorption process efficiency depends on the HNO3 concentration, contact time, initial metal concentration and temperature. Maximum sorption capacities amount to 0.46 +/- 0.023 mmol/g for La(III) ions and 0.38 +/- 0.019 mmol/g for Ni(II). To study the kinetics and process mechanism, the pseudo-first order, pseudo-second order equations, Weber-Morris intraparticle diffusion and Boyd models were applied. The equilibrium was described using the Langmuir, Freundlich and Temkin isotherm models. The desorption studies were also carried out. The morphology of ion exchanger was analyzed using scanning electron microscopy, optical microscopy and atomic force microscopy. The interactions of metals with the ion exchanger were confirmed by the attenuated total reflectance Fourier transform infrared spectroscopy, Raman and X-ray photoelectron spectroscopy before and after the sorption process. Furthermore, the point of zero charge of Purolite S957 was determined. The obtained results can be used to assess the potential of ion exchanger application for recovery of rare earth elements and heavy metals from spent nickel-metal hydride batteries.