Recovery of Mn0.8Zn0.2Fe2O4 from Zn–C battery: auto-combustion synthesizes, characterization, and electromagnetic properties

Mn0.8Zn0.2Fe2O4 ferrites were successfully prepared via a recycling process of spent Zn–C batteries (SZCBs) using sol–gel auto-combustion techniques and different fuels, including citric acid and sucrose chitosan, gelatin, and egg-white. The cost of this recycling technology, as well as the used fuels, have both economic and environmental advantages, facilitating many promising industrial applications. XRD confirmed single-phase formation with average crystallite sizes in the range from 15 to 55 nm. The appropriate cation distribution, elucidated using structural parameters, indicated the preferential occupancy of Zn+2 ions only by the A-sites while Mn+2 and Fe+3 ions preferentially occupy both A and B-sites. TEM images exhibited cubically agglomerated particles with wide size distribution. VSM indicated a wide range of magnetization values (51.0–19.8 emu/g) depending on the preparation route, suggesting the impact of the fuel used. The prepared ferrite using citric acid showed the highest value, while that prepared using egg-white indicated the lowest one. The obtained coercivities indicated soft magnetic materials with a decreasing behavior by increasing sizes. The ac-conductivity indicated semiconducting characteristics with a noticeable improvement in the conductivity than that of the bulk ferrite. The temperature dependence of the ac-conductivity showed a transition from ferro- to paramagnetic by increasing temperature. The estimated Curie temperatures (TC) indicated an improvement in the magnetic characteristics. In addition, the frequency dependence of ac-conductivity indicated a change in the conduction mechanism from the electron hopping to polaron type by increasing temperature. The very high dielectric values obtained in the order of 105 at low frequency warrant their application at low frequencies.