Selective Extraction of Zr(IV) over Hf(IV) from Aqueous Hydrochloric Acid with p-tert-Butylcalix[4]arenediphosphonic Acid
Selective Extraction of Zr(IV) over Hf(IV) from Aqueous Hydrochloric Acid with p-tert-Butylcalix[4]arenediphosphonic Acid
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DOI：
10.1246/bcsj.20190011
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发表时间：
2019-05-01
影响因子：
4
通讯作者：
Hattori, Tetsutaro
中科院分区：
文献类型：
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作者：
Morohashi, Naoya;Kato, Yutaka;Hattori, Tetsutaro
对叔丁基杯[4]芳烃二膦酸(L)从水溶液HCl、H2SO4和H3PO4中提取Zr（IV）和Hf（IV）。在不同浓度的HCl水溶液中，随着酸浓度的增加，Hf（IV）的提取率（E%）明显降低（0.5 M HCl为96%，7 M HCl为12%），而Zr（IV）的E%保持在中等水平（0.5 M HCl为90%，7 M HCl为60%）。因此，从高浓度的HCl溶液中可以选择性地提取Zr（IV）而不是Hf（IV）。当L与Zr（IV）的摩尔当量为7 M HCl时，分离因子S-Zr达到24。机理研究表明，L通过溶剂化机制从高浓度HCl溶液中提取Zr(IV)，形成1:1的络合物LZrCl4。Zr（IV）萃取后，用5 M H3PO4处理有机相，定量反萃取Zr（IV）。
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 similar to 60% at 7 M HCl). Thus, selective extraction of Zr(IV) over Hf(IV) is achieved from high-concentration HCl solutions. The separation factor (S-Zr) 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).