Mechanism of extraction of Fe [III], Fe [II], Co [II] and Ni [II] by Di- [2-ethylhexyl] phosphoric acid from sulphuric acid medium

ABSTRACT

Distribution ratio, D, for iron, cobalt and nickel as a function of acidity and extractant molarity has been determined in a sulphate-di [2-ethylhexyl] phosphoric acid [DEHPA] system using benzene or 2-ehtyl hexanol as non polar and polar diluents respectively. The extractability of Fe [III] by DEHPA in benzene goes through a minimum with increasing acidity of the aqueous phase. The divalent ions Fe [II], Co [II] and Ni [II] seem to be poorly extracted at low acidities [0.5-IM] with the formation of M [HX2]. On the other hand, Fe [III] exhibited the highest value of D suggesting of its separation from these divalent ions With 2-ethyl hexanol, the distribution ratio for all ions are lower than in benzene and the extraction proceeds through chelate formation of Fex3 or MX2 for Fe [II], Ni [II] and Co [II].