Solvent extraction of Fe3+ from the hydrochloric acid route phosphoric acid by D2EHPA in kerosene

It is necessary to remove Fe3+ from the hydrochloric acid route phosphoric acid before it is purified by tri-n-butyl phosphate (TBP), otherwise the final product will fail because of the excessive iron content. Di-(2-ethylhexyl) phosphoric acid (D2EHPA, HA) is effective for Fe3+ extraction. Therefore, the solvent extraction of Fe3+ from the HCl-route phosphoric acid by D2EHPA in kerosene is investigated. The effects of the extraction time, temperature and concentrations of phosphoric acid, D2EHPA, calcium chloride and Fe3+ on the extraction process are studied. The mechanism of the extraction is explained and the extracted species is demonstrated to be FeClA2·4HA. D2EHPA has a high efficiency for Fe3+ extraction from the synthesis and actual HCl-route phosphoric acid with extraction percent of 98.61% and 96.50%, respectively via a cross-current 3-stage extraction. The loaded organic phase is effectively stripped (99.9%) using 6 mol/L hydrochloric acid. The extractant also has a high stability under a closed operation condition. D2EHPA can serve as an adequate extractant for the extraction of Fe3+ from the HCl-route phosphoric acid.