Thermodynamic analysis on the thermal treatment of spent alkaline batteries-PVC blends under inert conditions

Abstract

Polyvinyl chloride (PVC) and Spent Alkaline Batteries (SAB) are produced and accumulated in large quantities. The absence of a sustainable recycling route for these wastes amidst a circular economy era makes it important to find a potential coupling route of their waste streams into useful products. Herein, the behaviour of zinc, manganese, and iron were tracked through a thermodynamics calculation of the thermal treatment of PVC mixed with SAB followed with a thermodynamic assessment of the leaching of the pyrolysis residues. thermodynamics calculations suggest that zinc and manganese can be extracted with a percentage of up to 100% if PVC is thermally treated with water washed SAB under pyrolytic conditions at a temperature of 300 °C. The residues from the thermal treatment (rich in zinc and manganese chlorides) should be then water leached (pH = 5 – 6) to recover Zn2+ and Mn2+. Water washing of the SAB should help in suppressing the extraction of both sodium and potassium as they can be omitted from the reaction system when SAB is washed with water. However, the major drawback under the conditions above is that iron will still be extracted with zinc and manganese which can potentially cause complications in the separation at a further stage. Nonetheless, this work lays the foundation for further studies (theoretical and experimental) related to the extraction of zinc and manganese from SAB by means of thermally treating it with waste PVC.

Keywords

• Battery waste recycling
• PVC recycling
• Thermodynamics
• Solubility
• ZnCl2
• MnCl2