Effects of structural changes of new organophosphorus cationic exchangers on a solvent extraction of cobalt, nickel and manganese from acidic chloride media

Abstract

The effects of structural changes of organophosphorus cationic exchangers on metal-distribution curves (extraction efficiency vs. pH) have been investigated for the recovery of cobalt(II), nickel(II) and manganese(II) from acidic chloride solutions. By using alkyl groups with different branching and hydrophobicity and by including oxygen atoms in the hydrophobic chains of the cationic exchangers, it has been shown that the change of the chemical structure in the hydrophobic chains plays an important role in the extraction behaviours and causes more specifically a shift of the extraction curves to higher or lower pH depending on pK a values of extracting agents (evaluated by using QSPR calculations), distribution constants of metal-ligand complexes between organic and aqueous phases and the formation constant of the metal-ligand complexes. Based on the present results, interest in the new cationic exchangers synthesized in the present work for cobalt(II), nickel(II) and manganese(II) separation is also discussed.

Recovery of cobalt from dilute aqueous solutions using activated carbon–alginate composite spheres impregnated with Cyanex 272

“…[11][12][13][14] Due to the rapidly growing rechargeable battery industry, mainly for its use in electrical vehicles, the demand for cobalt is increasing at a fast pace. [14][15][16] To meet this high demand in the future, cobalt recycling technologies must be further explored and/or improved. An additional benet of recovering cobalt is that possible environmental pollution is avoided, thus minimising exposure of this toxic element that is known to induce various adverse effects on the human health.…”

“…It proved to be very selective for cobalt over nickel extraction at pH 5-6. 15,61 However, Cyanex 272 is not suitable for the selective separation of cobalt from mixed cobalt(II)-manganese(II) solutions. 15,61 Cyanex 301 and Cyanex 302 are preferred for cobalt separation from manganese-containing solutions, but these extractants are not stable and were therefore not considered in this paper.…”

“…15,61 However, Cyanex 272 is not suitable for the selective separation of cobalt from mixed cobalt(II)-manganese(II) solutions. 15,61 Cyanex 301 and Cyanex 302 are preferred for cobalt separation from manganese-containing solutions, but these extractants are not stable and were therefore not considered in this paper. 62,63 The developed material would be similar to the commercially available Lewatit® TP 272, which is also a Cyanex 272 impregnated resin.…”

New cationic exchangers for the recovery of cobalt(II), nickel(II) and manganese(II) from acidic chloride solutions: Modelling of extraction curves

“…The most frequently used extracting agent for cobalt-nickel separation is Cyanex 272 (bis-(2,4,4-trimethylpentyl) phosphinic acid) (Flett, 2004). However, this extractant exhibits a low separation factor between cobalt(II) and manganese(II) both from acidic sulphate and chloride media (Omelchuk et al, 2017). Conversely, D2EHPA (bis-(2-ethyl-hexyl-phosphoric acid) is a suitable extractant for Co(II)-Mn(II) separation from acidic chloride solutions (Zhao et al, 2011) but it is not appropriate for Co(II)-Ni(II) separation.…”

“…Conversely, D2EHPA (bis-(2-ethyl-hexyl-phosphoric acid) is a suitable extractant for Co(II)-Mn(II) separation from acidic chloride solutions (Zhao et al, 2011) but it is not appropriate for Co(II)-Ni(II) separation. Indeed, pH for which the extraction efficiency of Mn(II), Co(II) and Ni(II) from acidic chloride solution is equal to 50% (pH1/2) are 4.0, 4.3 and 6.7 when Cyanex 272 is used and 2.2, 3.3 and 3.8 when D2EHPA is employed instead of Cyanex 272, respectively (Omelchuk et al, 2017).…”