Selective extraction of Zr(IV) over Hf(IV) from aqueous hydrochloric acid with p-tert-Butylcalix[4]arenediphosphonic acid

Naoya Morohashi, Yutaka Kato, Sahoko Sumida, Yu Kurusu, Tetsutaro Hattori

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

p-tert-Butylcalix[4]arenediphosphonic acid (L) extracts Zr(IV) and Hf(IV) from aqueous HCl, H2SO4, and H3PO4. In the extraction from aqueous HCl of different concentrations, the percentage of extraction (E%) of Hf(IV) decreases notably with an increase in acid concentration (96% at 0.5 M HCl and 12% at 7 M HCl), whereas the E% of Zr(IV) remains at a moderate level (90% at 0.5 M HCl and 360% at 7 M HCl). Thus, selective extraction of Zr(IV) over Hf(IV) is achieved from high-concentration HCl solutions. The separation factor (SZr) reaches 24 when using two molar equiv of L to Zr(IV) at 7 M HCl. Mechanistic studies indicate that L extracts Zr(IV) from high-concentration HCl solutions by a solvation mechanism by forming a 1:1 complex, LZrCl4. Back extraction of Zr(IV) proceeds quantitatively by treating the organic phase with 5 M H3PO4 after the extraction of Zr(IV).

Original languageEnglish
Pages (from-to)967-972
Number of pages6
JournalBulletin of the Chemical Society of Japan
Volume92
Issue number5
DOIs
Publication statusPublished - 2019

Keywords

  • Calixarene
  • Solvent extraction
  • Zirconium

ASJC Scopus subject areas

  • Chemistry(all)

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