Speciation and separation of platinum(IV) polynuclear complexes in concentrated nitric acid solutions
Speciation and separation of platinum(IV) polynuclear complexes in concentrated nitric acid solutions
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浓硝酸溶液中铂(IV)多核配合物的形态形成和分离
DOI：
10.1039/d1dt01392k
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发表时间：
2021
影响因子：
4
通讯作者：
Narita Hirokazu
中科院分区：
文献类型：
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作者：
Suzuki Tomoya;Otsubo Ukyo;Ogata Takeshi;Shiwaku Hideaki;Kobayashi Tohru;Yaita Tsuyoshi;Matsuoka Mitsuaki;Murayama Norihiro;Narita Hirokazu
了解铂(IV)的溶液化学对贵金属的湿法冶金至关重要。为了获得这样的认识，用PtLIII边X射线吸收精细结构(XAFS)谱研究了浓硝酸溶液中铂(IV)络合物的形态和分离。对浓硝酸氢钠溶液的XAFS结果表明，铂多核络合物是主要存在的，其中铂多核络合物的形成依赖于金属浓度和氢氧化钠溶解温度。在加热的0.90g-铂L−1和不加热的3.2g-铂L−1的硝酸盐溶液中，主要存在双核的铂(IV)配合物，而在3.0g-铂的L−1的加热溶液中，主要是较大的多核配合物，如四核和六核的配合物。XAFS光谱证实了较大的铂(IV)络合物的存在，考察了用亚氨基二乙酸官能化的螯合树脂和含三甲基硝酸铵的强碱性阴离子交换树脂从10M HNO3溶液中吸附铂(IV)离子的情况。用不同金属浓度的加热硝酸溶液和非加热溶液稀释的水溶液，测试了两种树脂对50 mg L−1对铂(IV)的吸附。我们发现，从含高浓度铂(IV)的加热溶液中得到的铂(IV)络合物具有很高的吸附百分率。用强碱性阴离子交换树脂从10M硝酸溶液中实现了Pd(II)、Ag(I)、Cu(II)、Ni(II)和Fe(III)对铂(IV)的选择性吸附。
Understanding the solution chemistry of Pt(IV) is crucial for the hydrometallurgy of precious metals. To gain such an understanding, the speciation and separation of Pt(IV) complexes in concentrated HNO3 solutions were investigated via Pt LIII edge X-ray absorption fine structure (XAFS) spectroscopy. The XAFS results for concentrated HNO3 solutions of Na2Pt(OH)6 revealed the dominant presence of Pt polynuclear complexes, wherein the formation of Pt(IV) polynuclear complexes depended on the metal concentration and the Na2Pt(OH)6 dissolution temperature. The dominant species present in a heated nitrate solution of 0.90 g-Pt L−1 and a non-heated nitrate solution of 3.2 g-Pt L−1 were dinuclear Pt(IV) complexes, whereas those in a heated solution of 3.0 g-Pt L−1 were predominantly larger polynuclear complexes, such as, tetra- and hexa-nuclear complexes. The presence of larger Pt(IV) complexes was confirmed via XAFS spectroscopy, wherein the adsorption of Pt(IV) ions from a 10 M HNO3 solution by a chelating resin functionalised with iminodiacetic acid and a strongly basic anion-exchange resin bearing trimethyl ammonium nitrate was examined. The adsorption of 50 mg L−1 of Pt(IV) by the two resins was tested using aqueous solutions diluted from heated HNO3 solutions with varying metal concentrations, and also from a non-heated solution. We found that Pt(IV) complexes from heating solutions containing high Pt(IV) concentrations displayed high adsorption percentages. In addition, the selective adsorption of Pt(IV) over Pd(II), Ag(I), Cu(II), Ni(II), and Fe(III) from a 10 M HNO3 solution was achieved using a strongly basic anion-exchange resin.