| 摘要: | 本提案承續先前微米級零價鐵之硝酸根脫氮，針對其氨氮(NH4+-N)產物之困擾問題進行改善研究。根據筆者早期研究及其它主要研究群之資料顯示，硝酸根在酸性水質條件下，幾乎完全被元素鐵還原成氨離子(NH4+)。因此，對於產生氮氣(N2 基本上來說，本計畫之研究構想，乃使用奈米級金屬材料，例如：Fe、Cu-Fe、Cu-Fe-Pd (其中，Fe為還原金屬、Cu為還原促進金屬、Pd為貴金屬)，配合各種氣體之運用，包括：氫氣、空氣、氮氣、及二氧化碳等，控制金屬材料系統之氧化還原電位(ORP)，以創造有利於氮氣之產生條件。經初步先期研究，使用非載體式之Fe(20%wt)-Cu系統，可以達到94%之NO)之理想反應，其生成反應機制之控制，是本研究之重點主軸。本研究乃試著以奈米級零價鐵為基材，製備雙或三金屬材料(bi- or tri-metals)，藉著反應條件之控制，以達到硝酸根最大去除率及最佳氮氣選擇性。 3-去除率、30%之N2選擇性。據此一可行性研究，本提案之研究架構包括：(1)控制系統ORP及pH兩參數以直接形成N2氣體；(2)在系統無法直接產生N2之情況下，選擇適當非載體式雙金屬(例如Fe(最適重量百分比)-Cu) 以產生最大量之NO2-；(3)階段式程序控制pH/DO/ORP將NO3-轉化成中間產物NO2-以及最終產物N2 本研究計畫以三年期程，完成以下研究內容：(1)非載體式奈米級金屬材料製備(包括：有無分散修飾劑)；(2)金屬材料之NO。 3-還原能力潛勢測試；(3)使用非載體式奈米級金屬材料及系統調控最大化NO3- - 了解本研究之金屬材料製備方法對於脫氮之影響效應(N還原產氮。本提案之研究成果，預期將包括以下幾方面： 2 - 提供本研究所製備金屬材料對於NO選擇性)； 3-之還原潛勢高低資訊(NO3- - 了解分散劑之使用，對於金屬材料穩定性、活性、傳輸性、粒徑大小之影響效應； 去除率)； - 確認直接產氮之系統條件(“pH維持中性範圍、ORP保持在零值左右”)，以及多階段間接產氮氣之操控條件。
Based on earlier research on nitrate denitrification by zero-valent iron of microscale, this proposal attempts to resolve the problem of undesired product ammonium. According to the outcomes of our group and some other researchers, nitrate was converted by zero-valent iron almost completely into ammonium under acidic solution condition. Therefore, aiming at ideal reaction of nitrogen gas formation, the focus of this proposal is placed on the control of nitrogen gas formation reaction mechanism. With nano zero-valent iron as core material, bi- or tri-metals will be prepared in the laboratory and employed for the maximum removal of nitrate and maximum selectivity for nitrogen gas formation through process condition control. Basically, the research idea of this proposal is to use nanometals such as Fe, Cu-Fe, Cu(promoting metal)-Fe(reducing metal)-Pd(noble metal), coupled with the use of various gases of H2, air, N2, and CO2, to control the oxidation and reduction potential (ORP) so that the favorable conditions of nitrogen gas formation can be created. According to our preliminary study, aqueous nitrate was removed by 94% and selectivity for nitrogen gas formation was around 30%. With such encouraging data available from our feasible study, research framework of this proposal is design as follows: (1) direct formation of nitrogen gas through system control of pH and ORP; (2) maximum nitrite formation through appropriate non-supported bimetals, e.g., Fe(optimum iron%) In summary, it is attempted to finish the following research items in three years: (1) preparation for non-supported nanometals in the absence and presence of modifying dispersants; (2) test of prepared nanometals for their nitrate reduction capacity potential; (3) maximizing nitrate denitrification through the use of non-supported nanometals and system control. As can be anticipated, the achievements of this proposal include: -Cu, if direct formation of nitrogen gas is not plausible; (3) indirect formation of nitrogen gas from nitrate to intermediate nitrite, and then to final product nitrogen gas through system control of pH, DO, and ORP as well as the use of appropriate nanometals. - Understanding of effect of nanometal preparation method on nitrate denitrification (nitrogen gas selectivity); - Providing of nitrate reduction capacity potential for nanometals prepared in this project (nitrate removal efficiency); - Understanding of the effect of modifying dispersant on nanometal in terms of stability, reactivity, transmissibility, and particle size; - Verifying of system conditions for direct nitrogen gas formation, and indirect nitrogen gas formation through multi-step control of system parameters. |
