- 期刊
不同螯合劑及pH值對於超臨界二氧化碳萃取酸性廢液中鎵離子影響之研究
Effects of Various Chelating Agents and pH on Supercritical Carbon Dioxide Extraction of Gallium Ions from Acidic Wastewater
摘要
半導體產業為國家重要的科技產業之一，在產量與產值不斷上升的同時，製程中所使用到的酸液和鎵金屬及其化合物也隨之提升。目前國內尚無適當的鎵金屬回收處理技術與機構，若無法有效的處理，使廢液長期推放，不僅可能對人體健康造成危害，更可能影響環境。所以如何從半導體製程酸性廢液中萃取稀有貴重的鎵金屬，並將其無機酸加以回收，將是未來一個新興的商機。因此本研究將利用具有綠色化學特性的超臨界流體萃取技術，萃取模擬半導體製程酸性廢液中之鎵離子；由於螯合劑在超臨界流體萃取技術扮演著關鍵的角色，所以本研究將探討不同螯合劑在一定超臨界二氧化碳條件下的萃取率比較，並以此最適螯合劑進行超臨界二氧化碳萃取實驗尋找其最適的萃取壓力、溫度和溶液pH值。其實驗結果整理如下：不同螯合劑的萃取率依序為PySH (82.8%)＞TTAH(66.8%)＞AcAcH (45.4%)；螯合劑PySH最適萃取壓力、溫度條件為壓力3000psi、溫度70℃；PySH最適溶液pH值範圍應落在2.0~3.0。
並列摘要
Gallium and its compounds have numerous industrial applications in the manufacture of semiconductor industry. Most of the gallium compounds and acidic wastewater are used in the process. Gallium compounds are considered hazardous materials that can be carcinogenic. Supercritical CO_2 extraction, which is a feasible ＂green chemistry＂ alternative, was applied in this study as a sample pretreatment step for extraction of gallium ions from acidic wastewater of the semiconductor industry. Several parameters, including various chelating agents, extraction pressure and temperature, and the pH of the solution, governing the efficiency and throughputs of the procedure were systematically investigated. The performance of the various chelating agents from different studies indicated that the extraction efficiency of supercritical CO_2 was in the order: PySH(82.8%)＞TTAH(66.8%)＞AcAcH(45.4%). The optimal extraction pressure and temperature for the supercritical CO_2 extraction of gallium (III) with chelating agent PySH were found to be 3000 psi and 70℃, respectively. The optimum pH of the solution for supercritical CO_2 extraction should fall in the range of 2.0-3.0.