Removal of Fe3+ from ammonium dihydrogen phosphate solution in an impact-jet hydraulic cavitation extractor

Abstract

The impurity of Fe3+ in ammonium dihydrogen phosphate (MAP) solution has a significant influence on the morphology and quality of products. The removal of Fe3+ from the MAP solution by Di-(2-ethylhexyl) phosphoric acid (D2EHPA) was investigated in an impact-jet hydraulic cavitation (HC) extractor. The organic phase and aqueous phase can be highly mixed under the action of hydraulic cavitation. The extraction efficiency of 80% can be achieved when the extraction reaction was carried out for only 5 min. It was found that the extraction of Fe3+ with D2EHPA was an exothermic reaction, and the equilibrium equation of extraction was obtained by slope method as follows: Fe(aqu)3++8HD2(org)=FeD3·13HD(org)+3H(aqu)+After the two-stage extraction, the extraction efficiency of up to 96.7% can be reached (only 3.4 ∼ 4 ppm Fe3+ remained in the aqueous phase), and the MAP crystals with regular polyhedral structure, single phase nature, and high optical transmittance were obtained.

Keywords

• Extraction
• Hydraulic cavitation
• Ammonium dihydrogen phosphate
• Fe3+
• Equilibrium equation