Waste of batteries management: Synthesis of magnetocaloric manganite compound from the REEs mixture generated during hydrometallurgical processing of NiMH batteries

In the present study, rare earth elements (REEs, i.e., La, Ce, Nd, and Pr) were hydrometallurgically recovered in oxalate form with presence of very low concentration Co, Al, Zn Ni from solution after processing spent Nickel metal hydride (Ni-MH) batteries. The mixture was used as alternative source synthesis magnetocaloric materials. this a manganite sample general formula ABO 3 selected to be prepared since it is relatively easy synthesize tuneable by adjustment doping concentration. conventional solid-state reaction method prepare an orthorhombic structure REE 2 O MnO secondary phases reported x-ray pattern at room temperature. thermomagnetic measurements showed PM FM transition 184 K 0.01 T magnetic field that shifts 194 increasing 1.8 T. properties determined calculating isothermal entropy change directly measuring adiabatic temperature change. A reversible effect observed.