Facile Synthesis and Application of Dibutyl Aminophosphonate Polymer for Robust Uranium Capture from Concentrated Nitric Acid Process Streams

ABSTRACT The recovery of trace uranium from strongly acidic streams generated during uranium processing is of critical importance due to associated radiological and toxicological hazards. Conventional solvent extraction processes are ineffective for such lean streams, and no commercially available ion‐exchange resins combine high selectivity with acid stability. In this work, a new polymeric sorbent, dibutyl aminophosphonate (DiBAP) resin, was prepared via a facile one‐step chemical modification of a commercial aminophosphonic acid resin. The DiBAP resin exhibits excellent selectivity for U(VI) (K _d ≈ 10 ⁴ ) over competing metal ions (Cu, Fe, Ni, Ca, Mg, Mn; K _d <30) in 2.0‐3.0 M HNO ₃ . Uranium sorption is rapid, reaching equilibrium within 1 h and following pseudo‐second‐order kinetics, indicative of chemisorption involving phosphonate functionalities. Sorption isotherm studies reveal monolayer uptake consistent with the Langmuir model. Quantitative back‐extraction of uranium was achieved using 2.0 M ammonium carbonate. Column experiments with simulated effluents confirmed efficient uranium removal at practical flow rates and more than tenfold concentration enhancement in the eluate. DiBAP resin thus provides a robust, selective, and reusable platform for uranium recovery from acidic streams.