Solvent extraction of titanium(IV) from orthophosphoric acid media using Aliquat-336/kerosene and stripping with nitric acid

Abstract

Titanium extraction from acidic solutions was investigated using Aliquat-336, considering factors like acid type and concentration for leaching, diluent type for solvent extraction, equilibration time, extractant concentration, phase ratio, and temperature. Kerosene exhibited superior performance as an aliphatic diluent for Aliquat-336 compared to other utilized diluents. The extraction efficiency was inversely proportional to the dielectric constant of the diluents. The quantitative Ti(IV) extraction efficiency from phosphoric acid (6 M H3PO4) leach liquor of ilmenite and rutile achived 98 % at room temperature (298 K) in 10 min after mixing with 0.1 M Aliquat-336 dissolved in kerosene at a phase volume ratio of 1:1 (Aq:Org). The exothermic extraction process occurred spontaneously. The proposed extraction mechanism using Aliquat-336/kerosene involves ion-pair association of the extractant with a Ti(IV) complex, confirmed by FTIR spectroscopy. The Ti(IV) ions were effectively stripped using HNO3 (3 M) with an aqueous:organic phase volume ratio of 1:1 at 25 °C after a contact time of 10 min in each step. The Aliquat-336/kerosene efficiently tested for Ti(IV) recovery from acidic Abu-Ghalaga ilmenite and rutile leachate. The findings indicate that, the phosphate medium is highly efficient in extracting Ti(IV), even with low concentration of Aliquat-336 in kerosene, especially in comparison to the impurities such as Fe, Cr, and Al. The EDX, XRD, and wet chemical analyses of the final product after the hydrolysis of stripped Ti(IV) from samples originating from the Abu-Ghalaga area and rutile samples, confirmed the formation of high-purity TiO2 (predominantly anatase phase). The SEM results showed particles with a regularly spherical structure and uniform size.