Separation of Hf(IV) and Zr(IV) using di(p-tert-octylphenyl) phosphate in sulfuric acid medium

Nuclear grade zirconium and hafnium are the key to promoting the development of nuclear industry. This study designed and synthesized a novel extractant, di(p-tert-octylphenyl) phosphate (DTOPPA), demonstrating that DTOPPA preferentially extracts hafnium and outperforms commercial extractants D2EHPA and PC88A. Under optimal conditions, the extraction rate of Hf(IV) reached 90.7%, and the separation factor between Hf(IV) and Zr(IV) reached a maximum of 13.4. Theoretical calculations suggest that the strong electron-withdrawing conjugated effect of the phenoxy group in DTOPPA reduces the electron density of the oxygen atom in the P-O-H bond, facilitating H ⁺ release, which is critical to its superior extraction performance.