CMP廢水電混凝中鐵離子效應之研究

Abstract

本實驗主要對於化學機械研磨液奈米顆粒之去除可以分為五個部份來討論: 第一部分為奈米顆粒的表面性質分析與凝聚理論的關係；第二部份為不同研磨廢液之混凝效率研究；第三部份為建立數學模型；第四部份為電混凝模型參數之探討；第五部份為DLVO理論探討電混凝程序之行為及印證數學模型參數。 實驗結果發現，對於兩種不同研磨液而言，其介達電位會隨著溶液之pH值而改變，是因為離子強度的原因，造成其電壓縮而改變其表面性質，亦改變了其粒子間之排斥能 。而在電混凝之處理效率上，此程序對兩種不同之研磨液之移除效率都非常良好，氧化層研磨液之電混凝通電流為1A時，在9~10分鐘幾乎就全移除顆粒，而金屬層則通電流0.45A，在相同時間亦可達相同的效果。 對於數學模型的建立，可以預測隨著電混凝的時間，顆粒濃度的變化，亦可從模型參數中得到通電時間之最低限值，即可達臨界凝聚濃度，金屬從大概約10.69mg/L，而氧化層大概為26.83mg/L，當釋鐵離子越過此臨界濃度，凝聚的機制便啟動，吾人亦由基本之凝聚理論求出理論臨界濃度，與數學模型比較之，可得知其值相去不遠，故推論對這模型之建立應可期應用在其他研磨液或廢水處理上。

This thesis on removing nano-particles from CMP wastewater by electrocoagulation process has mainly studied in five parts. The relationship between surface properties analyzing of nano-particles and the theory of coagulation was investigated in first part study. Efficiency of electrocoagulaion in different types of CMP was studied in second part. The mathematic model was built in third part. The parameters of the model in electrocoagulation process was investigated in the forth part. The behavior of particles in EC process and the parameters of model was investigated by DLVO theory in the fifth part. According to the experiment results of the two slurries, it was found that the zetapotential had changed by the pH value because of the strength of ion in solution. And it would lead to both the properties of surface and the repulsive energy between particles changed by electropressed. The efficiency of the particle abatement by EC treatment on two kinds of CMP slurry was perfect. As the operation current of EC treatment on oxide CMP slurry was 1A, the particles had almost been removed after 9~10 minutes EC time. The same result would be achieved in the same EC time by 0.45A operation current of mental CMP slurry treatment. According to the establishing of the model, the change of particle’s concentration along with EC time could be predict. And the lowest limited EC time could be found. It also mean that the concentration of Fe3+ were achieved c.c.c ( Critical Coagulation Concentration), then the mechanism of coagulaion would be started. And c.c.c of metal slurry was 10.69mg/L, and oxide slurry was 26.83mg/L. The theoretical c.c.c also could be found by DLVO theory. The value was closed to modeling one. So it could expect that the model could be applied to other slurry or wastewater treatment.