不同螯合劑對於超臨界流體萃取光電產業中含銦廢液影響之研究

TFT光電面板產業為國家兩兆雙星產業，但由於製程中會使用到大量的酸液及銦金屬，若能加以回收酸液及銦金屬將成為很大的商機，因此本研究利用具有綠色化學特性的超臨界萃取技術去除光電產業製程蝕刻廢液中之銦金屬，而螯合劑在超臨界萃取技術扮演著關鍵的角色，所以本研究亦嘗試自行合成螯合劑來提高萃取率。內容主要分為有機合成與超臨界萃取蝕刻廢液中之銦金屬兩部分；有機合成方面，以銦金屬和螯合劑乙醯丙酮Acetylacetone(acac)所結合形成的金屬錯合物In(acac)_3為反應起始物與選購的含壁吡啶配位基(piperidine；PySH)反應作為合成螯合劑先期研究；根據合成結果，以含二硫代胺基的配位基與二硫化碳螯合得到螯合劑(C_3H_6(CO)_2NC(S)SH、C_5H_(10)NC(S)SH)，再將合成的螯合劑應用於超臨界萃取技術去除製程蝕刻廢液中之銦金屬。經超臨界二氧化碳萃取製程蝕刻廢液中之銦金屬實驗結果與文獻使用的螯合劑比較結果為：C_3H_6(CO)_2NC(S)SH (90.8%)＞PySH(85.4%)＞TTA(75.4%)＞TAA(70.3%)＞C_5H_(10)NC(S)SH (69.3%)＞acac(45.6%)。

關鍵字

超臨界流體萃取；銦；螯合劑；蝕刻廢液；銦錫氧化薄膜

並列摘要

Indium-Tin oxide (ITO) is an optically transparent conductor which is used in the making of thin-film transistor liquid crystal displays (TFT-LCD) and photo-voltaic cells. Most of the metal indium and solvents are used in the ITO process and are considered hazard materials that can be carcinogenic. Due to its inexpensive, non-toxic natures and its need for mild operating condition, supercritical fluid extraction using carbon dioxide (SF-CO_2) was utilized in this research as a sample pretreatment step for recovering indium from simulated wastewater of ITO process. After sample pretreatment, the indium concentration in simulated etching wastewater was directly quantified by Flame Atomic Absorption Spectrophotometer (FAAS). However, direct extraction of metal ions by SF-CO_2 is not feasible owing to the requirement of charge neutralization and the weak solvent interactions. One suggested approach for extracting mental ions by SF-CO_2 is to convert charged species into metal chelates using chelating agents followed by SF-CO_2 extraction of mental complexes. The two goals of the study are as follows: The first is to conduct the syntheses of metal chelating ligands that can be applied in the green chemistry system. The second is to evaluate supercritical fluid extraction (SFE) combined with FAAS to remove the indium ion from simulated waste etchant of optoelectronics. Major advantages of extracting metal Indium using supercritical CO_2 include minimization of waste solvent generation and direct removal of metal from etchant waste. The extraction efficiency of the SF-CO_2 technology indicated that the performance of the chelating agents is in the following order: C_3H_6(CO)_2NCS(S)H (90.8%)＞PySH(85.4%)＞TTA(75.4%)＞TAA(70.3%)＞ C_5H_(10)NC(S)SH (69.3%)＞acac(45.6%).