In this study, Diphonix resin containing sulfonic, diphosphonic and carboxylic groups was used to evaluate the adsorption capacity of metal ions contained in the nickel-metal hydride batteries (Ni-MH). This type of ion exchanger can be considered as the multifunctional material having great affinity to many metal ions. Using Diphonix resin adsorption process was carried out for La(III) and Ni(II) ions to characterize kinetic, adsorption and thermodynamic parameters. Preliminary studies of the Nd(III), Ce(III), La(III), Fe(III), Co(II), Ni(II), Cu(II) and Zn(II) metal ions mixture were also performed. The best results of adsorption studies were obtained using 0.2 M HNO₃. Diphonix resin exhibits especially good adsorptive properties with respect to rare earth element ions (adsorption efficiency of about 100%) in comparison with the heavy metal ions in the second oxidation state (about 50% or below). The series of affinity of the resin for the studied ions can be presented as follows: La(III) > Fe(III) > Nd(III) > Ce(III) > Cu(II) > Zn(II) > Co(II) > Ni(II). The obtained results confirmed the possibility of further use of the resin for the recovery and separation of rare earth elements from solutions after Ni-MH batteries leaching.

The paper investigated the adsorption of the packed-bed column with the alginate-based adsorbents (ALG-based adsorbents) such as alginate-biochar, alginate-clinoptilolite, alginate-lignin, and alginate-cellulose for La(III) ions’ removal. Fixed-bed adsorption studies with various alginate-based adsorbents were carried out and compared to the La(III) ions adsorption. The columns were filled with ALG-based adsorbent beads of approximately 1.1 ± 0.005 mm spherical shapes. The effects of the inlet concentrations on the breakthrough curves were studied in terms of the adsorption performance of the ALG-based adsorbents. The experimental data were correlated with the Adams-Bohart, Yoon-Nelson, Thomas, and Wolborska models to determine the best operational parameters. Based on the comparison of R² values, the Thomas and Yoon-Nelson models were found to be more suitable than the Adams–Bohart and Wolborska models. In the desorption study, the ALG-based adsorbents packed columns showed the maximum desorption of La(III) just after passing 100 cm³ of 1 mol/dm³ HCl. Overall, the results show that ALG-based adsorbents could be used for continuous recovery of La(III) ions from aqueous solutions and were not only cost-effective but also environmentally friendly.