Solvent Extraction of Nickel and Zinc from Nitric Acid Solution Using D2EHPA: Experimental and Modeling

The present communication investigates the reaction mechanism of extraction of Zn(II) and Ni(II) and thermodynamic modeling using di-(2-ethylhexyl) phosphoric acid (D2EHPA) as an organic extractant that is diluted in kerosene at T = 25 degrees C and the organic: aqueous phase ratio of 1:1 and pH range 2-6. The effect of two important parameters i.e. concentration of extractant and pH on the extraction of metals were investigated. The experimental tests allowed us to define the best process conditions, among various investigated conditions, to extract Ni(II) and Zn(II) from filter cake. The optimized extraction values of Ni(II) and Zn(II) were 95.5 and 95.1%, respectively and these were obtained within one stage by 25% (v/v) concentration of D2EHPA, 60 min of contact time and rotation speed of 600 rpm. Moreover, the extraction reaction stoichiometry of Ni(II) and Zn(II) was determined using the slope analysis. Also, the activity coefficient of all ions in the aqueous phase and all of the organic components in the organic phase were predicted based on Electrolyte- universal quasichemical-NRF and universal quasichemical-NRF model. The obtained results indicated well agreement with the experimental data.