流體化床芬頓程序是一套結合化學氧化與結晶之技術,本研究將此法應用於苯胺合成廢水之處理上。其原理,主要是利用亞鐵與過氧化氫產生具有強氧化力之氫氧自由基來氧化污染物,此外系統中的擔體會吸附鐵污泥,覆膜結晶於擔體表面上,本研究以批次反應進行。
結果發現,流體化床芬頓程序與芬頓程序氧化苯胺反應行為相似。在流體化床方面,苯胺的分解與起始pH值、亞鐵離子劑量、過氧化氫劑量、苯胺處理濃度有關,隨著亞鐵離子劑量與過氧化氫劑量增加,苯胺氧化速率增加;擔體覆膜長晶量與起始pH值、過氧化氫劑量、擔體添加克數有關。
動力探討方面,使用兩階段反應模式來表示,第一階段求反應前5分鐘內的苯胺平均氧化速率,第二階段求反應5到30分鐘的反應常數K值。本研究使用兩種擔體(A1及B1)做為比較,在A1擔體系統中,求得苯胺平均氧化速率與反應常數K值,分別為15.40×10-4 M min-1與3.67×10-2 min-1;在B1擔體系統中求得苯胺平均氧化速率與反應常數K值,分別為16.00×10-4 M min-1與4.94×10-2 min-1。
比較傳統芬頓與流體化床芬頓程序氧化苯胺,結果發現低pH值與低亞鐵離子濃度下,流體化床芬頓程序比芬頓氧化苯胺效率為佳,原因是流體化床程序有同相與異相反應,皆能產生強氧化力的氫氧自由基氧化苯胺。流體化床程序確實有減少鐵污泥的效果,最高可達66.80﹪,而進行Fenton程序試驗時,系統中的總鐵殘餘率只有少量減少。
從擔體鐵氧化物分析發現,A1與B1覆膜鐵中結晶比例,各別為39.91﹪與48.56﹪。 Fluidized bed(FB)Fenton process combines oxidization and crystallization reactions. It was employed to the treatment of synthetic aniline solution in this study. This method applied ferrous ions and hydrogen peroxide to produce hydroxyl radicals for oxidizing the contaminants, and the occurred crystallization of iron sludge on the carrier surface.
Results show that FB Fenton and Fenton process have a similar. In the FB Fenton process, the initial pH, ferrous ion, hydrogen peroxide and aniline concentration would affect the degradation of aniline. The reaction rate increased with increasing ferrous ion and hydrogen peroxide concentration. The initial pH, hydrogen peroxide concentration and carrier dosage affected the adsorption and crystallization of iron sludge on the carrier surface.
Two-stage model is applied to describe the reaction kinetics. At the first stage average rate was calculated the first 5 minutes of reaction. At the second stage, data were regressed to obtain the rate constant, K. In this study, two kinds of carries(A1 and B1)were applied for comparison. In the A1 system, average oxidation rate of aniline was 15.40×10-4 M min-1 and constant K of aniline was 3.67×10-2 min-1;In the B1 system, average oxidation rate of aniline was 16.00×10-4 M min-1 and constant K of aniline was 4.94×10-2 min-1.
Comparing FB Fenton and Fenton process, we found that aniline removal efficiency by FB Fenton process was better than the conventional one at low pH and low ferrous ion concentration. Because FB Fenton process has homogeneous and heterogeneous reactions, both of them can produce powerful hydroxyl radicals for oxidizing the contaminants.
According to the analysis of iron oxide on the carrier surface, crystallization ratio of A1 and B1carrier were 39.91﹪and 48.56﹪,respectively.