Solvent extraction of nickel(II) ions from aqueous solutions using triethylamine as extractant

In this study, we investigated the solvent extraction of Ni(II) from aqueous solution using triethylamine (TEA) in hexane as the diluent. We monitored the influence of the pH of the aqueous phase, the concentration of TEA, the equilibrium time, the aqueous-to-organic (A/O) ratio, and the initial Ni(II) concentration in the aqueous phase. The extraction of Ni(II) was most effective at pH 4.5. An increase in the extractant concentration from 1.0 to 4.0% in the organic phase increased the extraction efficiency toward nickel ions. The maximum extraction (99.6%) was achieved when using 5.0% TEA (extractant) in hexane (diluent) at remove 50 mg/L of Ni ions from 50 mL of the aqueous phase. The extracted Ni(II) was stripped effectively from the organic phase using 0.5 M HCl as the stripping reagent. The stripped solvent mixture (TEA/hexane), when reused, retained its ability to extract Ni ions.