以具分散反萃取相支撐式液態薄膜回收廢棄釹磁鐵中之稀有元素釹並發展高值化光催化劑

Recovery of Neodymium from Waste Permanent Magnet by Support Liquid Membrane System and Develop High Quality Photocatalyst

劉宜憲(Yi-Hsien Liu)

指導教授 ： 游勝傑 ； 王雅玢

中原大學/工學院/環境工程學系/碩士(2017年)

https://doi.org/10.6840/cycu201700509

摘要

本研究使用具分散反萃取相支撐式液態薄膜(Supported Liquid Membrane with Strip Dispersion，SLMSD)，透過兩步驟程序進行釹金屬的回收與純化。高科技產業為我國經濟發展的基礎，而稀土資源更是為製造高科技產業之關鍵材料。然而我國並無出產稀土元素或稀有資源等工業發展之關鍵物質，原物料均仰賴進口，且隨著近年來電動車的興起，對於釹的需求量也隨之提昇。因此如何有效地從廢棄產品中，回收並純化稀土金屬，進而應用、高值化，是為一個重要的課題。
根據磁鐵粉末的表面分析與王水全溶出實驗結果顯示，廢磁鐵粉末中含有約42%的金屬釹可供回收。實驗將以酸浸法將金屬溶於酸液中，並在3M硫酸、固液比1g/50mL的配置下可以獲得最佳溶出結果，每公斤磁鐵粉約可溶出483克的釹。而根據萃取搖瓶實驗的結果顯示，當萃取劑(D2EHPA)的濃度控制在0.6M、進料酸鹼值調整至1.26~2.00時，可以得到99%以上的萃取效果，而6M的硝酸溶液可以有效的將有機萃取相中的金屬離子分離並反萃取至水相溶液中。經過SLMSD連續回收經過草酸沉澱處理後的粉末，可將進料濃度658ppm提升至4120ppm，約濃縮6.26倍，其純度約為90%。
此外，本研究利用釹對二氧化鈦光觸媒進行可見光改質，改善文獻中的溶膠凝膠法製備過程，在前驅物比例13:6:1(鈦源:異丙醇:硝酸)的條件下可以製備高催化活性的二氧化鈦，並搭配釹摻雜比例0.50wt%、陳化處理、去除表面有機物、升溫速度，可以製備出具銳鈦礦相的可見光光觸媒。經過20w的LED燈照射180分鐘後，每克光觸媒可以去除約23毫克之RB5偶氮染劑。
因此，本研究所使用的之SLMSD可有效回收廢棄釹磁鐵中的稀土元素釹，並
應用於二氧化鈦摻雜改質、成功改善二氧化鈦之缺點，並開發出高效能之可見光光觸媒。

關鍵字

釹鐵硼磁鐵、支撐式液態薄膜、溶膠凝膠法、二氧化鈦、可見光光催化

並列摘要

Neodymium (Nd) is a rare earth element (REE) that is also found in waste permanent magnets (WPMs). Permanent magnets (PMs) play an important role in manufacturing products as their demand is crucial in emerging countries such as Taiwan. Removing these waste products as well as enhancing the quality is very important for the recovery of these rare earth metals.The aim of the study is to recover and recycle Neodymium from waste permanent magnets (WPMs) by using a supported liquid membrane with strip dispersion (SLMSD) module with hollow fiber membrane. Thereafter, Neodymium would be used to enhance a high-quality photocatalyst.

Experimental results have shown that one gram of WPMs contained 450 mg of neodymium and 3M of H2SO4 can leach the maximum amount of neodymium ion in the powder and 3M of H2SO4 can leach the maximum amount of neodymium ion in the powder. The highest extraction efficiency of the pH feed phase (1.26 ~ 2.00), 0.6 mol/L of D2EHPA and as well as having the most effective solid-liquid ratio at 1:2. Nitric acid of 6M can strip all neodymium ions from the extractant with the O/A ratio 2:1. In addition, the operation of the hollow fiber SLMSD under this optimum condition showed a computable, the concentration of neodymium the strip solution was around 4120 mg/L while the initial concentration of neodymium in feed solution of 658 mg/L after a continuous extraction for 45min. Furthermore, the enhancement activity of a photocatalyst was obtained with a doping ratio at 0.5 wt% neodymium to remove 96% of RB5 under a fluorescent lamp. The best of calcination temperature was found to be 4000C for two hours. The fluorescent lamp has a relatively good catalytic efficiency and low power consumption.
Thus, the SLMSD used in this study could recover the Neodymium from waste neodymium magnets effectively. And Neodymium used in the doping of titanium dioxide could be synthesized successfully and improved the shortcomings of titanium dioxide. Finally, the Neodymium doped titanium dioxide could present high catalytic activity under the visible light irradiation.

並列關鍵字

Recycling economy, REEs, SLMSD, Neodymium, Photocatalysis

參考文獻

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