Scholarlink

<p>The presence of uranium (U(VI)) and thorium (Th(IV)) impurities in rare earth chloride liquids poses significant environmental and economic challenges. This study presents a novel and efficient method for their removal by synergistically coupling hydroxylamine hydrochloride (NH₂OH·HCl) reduction with adsorption onto a cerium-rich residue (CRR). The key process parameters, including CRR dosage, CeO₂/NH₂OH·HCl molar ratio, and reaction temperature, were systematically optimized. Under the optimal conditions (25&#xa0;g CRR, molar ratio of 1:0.3, 40&#xa0;°C), exceptional removal efficiencies of 98.02% for Th and 98.21% for U were achieved within a mild pH range of 3.2–3.7. The mechanism involves the NH₂OH·HCl-driven reduction of Ce(IV) in CRR to Ce(III), generating OH⁻ ions in situ that are proposed to facilitate the precipitation of uranium and thorium hydroxides ( e.g., UO₂(OH)₂ and Th(OH)₄), which are subsequently adsorbed onto the high-surface-area CRR. This integrated “reduction-precipitation-adsorption” approach proved superior to conventional neutralization with pure CeO₂, effectively preventing the loss of valuable rare earths associated with high-pH operations. Furthermore, CRR demonstrated good regenerability, maintaining over 90% removal efficiency for both U and Th through two consecutive cycles, although a gradual decline was observed thereafter due to active component loss and impurity accumulation. This work provides a green and cost-effective strategy for radioactive element removal in rare earth refining, with considerable potential for industrial application pending further improvement in long-term adsorbent stability.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Efficient Removal of U(VI) and Th(IV) from Rare Earth Chloride Liquids via Hydroxylamine Hydrochloride Reduction with Cerium-Rich Residue

  • 期刊论文

  • 发表日期：

    2026年5月6日

查看全文
  • An Guo,
  • Xinjin Xiao,
  • Liusheng Ge,
  • Qiaofa Lan,
  • Di Wu,
  • Xiaoqiang Wen,
  • Desheng Huang,
  • Sheng Zhong

摘要

The presence of uranium (U(VI)) and thorium (Th(IV)) impurities in rare earth chloride liquids poses significant environmental and economic challenges. This study presents a novel and efficient method for their removal by synergistically coupling hydroxylamine hydrochloride (NH₂OH·HCl) reduction with adsorption onto a cerium-rich residue (CRR). The key process parameters, including CRR dosage, CeO₂/NH₂OH·HCl molar ratio, and reaction temperature, were systematically optimized. Under the optimal conditions (25 g CRR, molar ratio of 1:0.3, 40 °C), exceptional removal efficiencies of 98.02% for Th and 98.21% for U were achieved within a mild pH range of 3.2–3.7. The mechanism involves the NH₂OH·HCl-driven reduction of Ce(IV) in CRR to Ce(III), generating OH⁻ ions in situ that are proposed to facilitate the precipitation of uranium and thorium hydroxides ( e.g., UO₂(OH)₂ and Th(OH)₄), which are subsequently adsorbed onto the high-surface-area CRR. This integrated “reduction-precipitation-adsorption” approach proved superior to conventional neutralization with pure CeO₂, effectively preventing the loss of valuable rare earths associated with high-pH operations. Furthermore, CRR demonstrated good regenerability, maintaining over 90% removal efficiency for both U and Th through two consecutive cycles, although a gradual decline was observed thereafter due to active component loss and impurity accumulation. This work provides a green and cost-effective strategy for radioactive element removal in rare earth refining, with considerable potential for industrial application pending further improvement in long-term adsorbent stability.