- 學位論文
以超臨界二氧化碳萃取廢棄印刷電路板中之有機物之探討
A Study on Extraction of Organic Compounds from Waste Printed Circuit Boards by Supercritical Carbon Dioxide
摘要
廢棄印刷電路板大多以焚化或直接掩埋法處理，然而廢印刷電路板中含有溴化阻燃劑，經由燃燒過程可能產生對人體有害之持久性有機污染物溴化戴奧辛/呋喃；直接掩埋法，可能導致有害金屬溶出，造成環境之二次污染。本研究以無毒性、無危害性之超臨界二氧化碳萃取廢印刷電路板中之有機化合物，將有機化合物與無機金屬分離，以便進行廢印刷電路板之回收處理。 鑒於純超臨界二氧化碳對於有機化合物之萃取能力有限，故本研究於靜態萃取中添加甲醇作為輔助溶劑，co-solvent，以提升超臨界二氧化碳對於有機化合物之萃取能力。研究中以二水準因子實驗設計法探討萃取時間(1hr、4hr)、溫度(200℃、300℃)、甲醇之添加量(無添加、添加100μL)等操作參數對萃取率之影響進行探討。經由實驗及數據分析顯示，其主要之影響因子為萃取溫度，當溫度設為高水準(300℃)時萃取之效果有顯著之提升；當溫度設為低水準(200℃)時萃取效果較差。於高溫下進行超臨界二氧化碳萃取之廢印刷電路板，經過高溫萃取過後會產生顏色變化或形變。於200℃(含)以下之溫度進行超臨界二氧化碳萃取之廢印刷電路板，其形狀並無改變但有些許焦色；於200℃以上之溫度進行超臨界二氧化碳萃取之廢印刷電路板，其電路板變得易碎且顏色焦黑如炭。由於高溫會對廢印刷電路板之結構造成破壞，故於高溫下進行超臨界二氧化碳萃取能萃取出較多、濃度較高之化合物。相較於溫度之影響，萃取時間與甲醇添加量兩影響因子之影響效果較不顯著。
並列摘要
Incineration and direct disposal have been applied to treat the waste printed circuit boards. However, polybrominated dibenzo-p-dioxins and dibenzofurans may be formed during the combustion of waste printed circuit boards containing brominated flame retardants; heavy metals can be easily leached out by water and cause secondary pollution in the environment. In this study, supercritical CO2 was investigated to extract the organics of waste printed circuit boards for further recovery. The effects of reaction factors (temperature, time, and addition of methanol) on extraction efficiency were determined by factorial experimental design. Results showed that reaction temperature has significant effect on extraction efficiency; waste printed circuit boards were decomposed under high temperature and thus increase the extraction efficiency. As for factors of reaction time and addition of methanol, their effects on efficiency were insignificant.