請用此 Handle URI 來引用此文件: http://hdl.handle.net/11455/5137
標題: 迴流式電動力法處理受銅,鋅污染的農地土壤之研究
Removal of Zinc and Copper from farmland soil by electrokinetic technology: effect of electrolyte circulation
作者: 洪敬堯
YAO, HUNG CHING
關鍵字: Circulating Electrical Kinetics
迴流式電動力法
acidification
heavy metals
酸化現象
重金屬
出版社: 環境工程學系
摘要: 電動力法在土壤重金屬污染整治上是一個有效且符合經濟效益的復育方法,但在處理的過程中,常會因為電解作用在陽極槽產生的氫離子引起系統的酸化及極化現象,造成處理的中止;且金屬沉澱物經常累積於操作模場之中段或末段,對整體處理效果有極負面影響。其次,陰極電解液之大量出流液,除了須再處理同時亦提高了所耗成本。因此本研究設計一套循環迴流之水平管柱,使陰極流出液循環至距離陰極出流口不同位置,探討於各區段改善酸化現象之效果,冀能找出ㄧ最佳迴流地點,能夠維持整體系統的pH值平衡。另一方面,由於迴流液的再利用,亦可達到經濟且減少二次公害之目的。 基礎電動力實驗中,三種操作液:自來水、0.5M檸檬酸、0.1MEDTA對於銅的去除率分別為13.77﹪、35.27﹪與23.53﹪;鋅的去除率分別為12.73﹪、28.85﹪、65.45﹪,且以EDTA為操作液時有最長之有效處理時間。因此,選擇0.1MEDTA為迴流式電動力法之陽極操作液,並以0.01M醋酸為陰極操作液,以迴流速率0.2ml/min於酸化發生時間進行迴流式電動力實驗。 在迴流式電動力實驗中,可發現將陰極出流液迴流至土壤酸化處,對於處理效果有顯著的提昇。對於銅的去除率可提高至72.95﹪,對於鋅的去除率些微降低至56.12﹪,此應該為銅和鋅對於EDTA的競爭錯合有關,但是對於整體之復育效果應該是有明顯的助益。 關鍵字:迴流式電動力法、酸化現象、EDTA、重金屬
To ameliorate the toxication caused by heavy metals within a polluted soil, the electrical kinetics is a good restorative means to cope with this hardship along with its efficacy and efficiency. However, the process of electrical kinetics has three inevitable disadvantages. First, the process itself is usually halted by the emergence of the acidification and the polarization effects caused by the hydrogen ions coming from the anode due to the electrolysis. Second, the accumulations of metal deposits throughout the processing usually lie around the middle or rear parts of the apparatus. Such accumulations have massively negative drawbacks on the whole efficacy. Third, we need extra cost and efforts to handle the huge amount of washing fluid coming directly from the cathode. In this research, by devising a system of horizontal tube combined with circulating currents, we can lead the cathode electrolyte to circulate around the various specific spots of the conduit. Afterwards, by investigating those different processing effects of the aimed and intensified washing action,we hopefully can discover the best circulation spot to maintain the balance of pH value within the processing system. Furthermore, with the help of re-utilization of the electrolyte, this devised process can also approach the other two ultimate targets: the economical benefit and the reduction on the secondary pollution. Proceeding the fundamental Electrical Kinetics experiments, using three processing fluid: tap water, 0.5M citric acid, and 0.1M EDTA, we come into the results of the removal rate on copper and zinc are: 13.77%, 35.27%, 23.53% and 12.73%, 28.85%, 65.45% respectively. In the meanwhile, when taking EDTA as the processing fluid, we can have the longest duration of treatment.Hence, we choose the 0.1M EDTA as anode electrolyte and the 0.01M citric acid as cathode electrolyte. Subsequently, we manipulate the Circulating Electrical Kinetics (CEK) experiments on the circulating rate of 0.2ml/min during the acidification phase. According to the CEK experiments, the results show that if we circulate the cathode flowing fluid to the acidification spots of soil, the improvement on the processing benefits will advance significantly. For the copper, the removal rate can remarkably lift to 72.95%. For the zinc, the removal rate slightly lower to 56.12%. This outcome should have relevance with the competition with EDTA between copper and zinc. As for the entire ameliorating achievements on the polluted soil, the CEK ought to have vital enhancement toward resuscitating the salubrity of such soil to some great extent. Keywords: Circulating Electrical Kinetics, acidification, EDTA, heavy metals
URI: http://hdl.handle.net/11455/5137
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