Selective extraction of Hf over Zr by a novel extractant ( n -octyl)(2,4,4′-trimethylpentyl)phosphinic acid (INET-1) from sulfuric acid media

A new Zr/Hf separation system was developed with a novel unsymmetrical dialkylphosphinic acid extractant ( n -octyl)(2,4,4'-trimethylpentyl)phosphinic acid (INET-1). It selectively extracts Hf over Zr, and shows much better Zr/Hf separation efficiency than organophosphorous acid Cyanex 272. The Zr and Hf extraction reactions at acidities of < 2 mol/L H 2 SO 4 and > 5.5 mol/L H 2 SO 4 are revealed, respectively. An organic phase with 10 mmol/L INET-1 can load > 290 mg/L of Hf at 1 mol/L H 2 SO 4 . Acidic H 2 SO 4 solutions with concentration of 3.0–4.5 mol/L is a good Zr scrubbing agent.