The distribution data for phosphoric acid (PA) and the major impurities (MgO, Al2O3, Fe2O3, CaO, SO42- and F-) during purification of wet process phosphoric acid (WPA) with tributyl phosphate (TBP) at 25°C are reported. TBP presents a good extraction power, extracting PA even from low concentrated phosphoric medium. The selectivity of TBP for PA against each impurity has been studied as a function of the PA concentration (wt %) in the organic phase. Our results are compared to those obtained with other solvating solvents (dibutyl ether, methyl isobutyl ketone, diethyl ketone and isoamyl alcohol) described in the literature. With regard to metallic impurities, TBP selectivity is always intermediate between those of isoamyl alcohol and dibutyl ether.
R. Dhouib-Sahnoun, M. Feki, H. F. Ayedi