Solvent Extraction of Manganese and Zinc from Chloride Leach Solution of Spent Zn–C Batteries with DEHPA in Benzene Diluent

The applicability of utilizing solvent extraction processes of manganese (Mn) and zinc (Zn) from chloride leachate of spent zinc–carbon (Zn–C) batteries has been studied by using di-2-ethylhexyl phosphoric acid (DEHPA) as an extractant agent. The effect of five factors (equilibrium pH, O/A ratio, temperature, extractant concentration, and diluent type) were investigated. According to the results gained, the appropriate solution pH level for DEHPA was found to be 6.5. With DEHPA (20%, v/v), 77.50% Mn and 100% Zn were extracted, within 15 min contact time at a 1:1 aqueous/organic ratio and 50 °C temperature. Also, a McCabe–Thiele diagram was drawn and one single-step extraction for Zn and a two-stage process for Mn were needed to achieve the highest extraction efficiency. ΔH as a thermodynamic parameter was calculated and found to be 18.39 kJ/mol for Mn and − 245.50 kJ/mol for Zn, respectively, indicating that the extraction process was endothermic for Mn and exothermic for Zn. A desirable stripping of Mn and Zn from the loaded organic phase could be obtained using a stripping solution of 6 M HCl.