A study of biochemical route on construction of waste battery ferrite applying for nickel removal.

Mn-Zn ferrite (MnZnFeO, x = 0.2, 0.4, 0.6, and 0.8) nanomaterials were prepared by bioleaching and hydrothermal synthesis from waste Zn-Mn batteries. The materials were characterized by XRD, SEM, BET, VSM, CEC, and isoelectric point. It turned out when x = 0.4, synthesized Mn-Zn ferrite had best performance which was nanoferrite crystal structure with a specific surface area that reached 37.77 m/g, the saturation magnetization was 62.85 emu/g, and isoelectric point and the CEC value were 7.33 and 43.51 mmol/100 g, respectively. In addition, the adsorption characteristics on Ni were explored. The results of experiment suggested that data was more in line with the Freundlich model compared with Langmuir and Dubinin-Radushkevich isotherm models. Kinetics studies showed that pseudo-second-order kinetics was more suitable for describing the Ni adsorption process where the maximum theoretical adsorption quantity was 52.99 mg/g. Thermodynamic parameters indicated the adsorption process can be spontaneous as an endothermic reaction, and warming was advantageous to adsorption. Besides, the adsorbent could be reused for six cycles with high removal efficiency. The magnetic and adsorptive properties of the adsorbent were promising, which had a high application value. Graphical abstract Fabrication process of nanometer ferrite by biological technology and hydrothermal synthesis for removal of Ni2.