Extraction of uranium from low-concentration solutions using P204 bubbling organic liquid membrane technology

The uranium leaching process generates a substantial volume of wastewater, in which the uranium is difficult to concentrate and recover due to its extremely low concentration. In this study, the bubbling organic liquid membrane extraction method using Di-(2-ethylhexyl) phosphate (P204) as the extractant was proposed and evaluated for the effective enrichment and recovery of low-concentration uranium. The effects of the organic to aqueous phase ratio (O/A), the initial pH value of the wastewater, the initial uranium concentration and coexisting ions on the uranium recovery were investigated. The results indicated that the uranium recovery increased with the initial solution pH. A relatively high uranium recovery of 94.3% was achieved at pH 6 and an O/A ratio of 1:10. The uranium recovery decreased with increasing initial uranium concentration. Furthermore, elevated concentrations of Al<sup>3+</sup>, Fe<sup>3+</sup>, and Mg<sup>2+</sup> in the aqueous phase were found to adversely affect uranium extraction, likely due to competitive coordination with the extractant or interference with the extraction equilibrium.