硝酸鹽為地下水體中最常見的污染物之一。硝酸鹽過量攝入人體之所以有害，乃因硝酸鹽進入腸道後易被還原為亞硝酸鹽。亞硝酸鹽會引起血紅素中的鐵氧化變性，喪失攜氧能力；另外亞硝酸根離子會與人體消化道中的二級胺形成亞硝胺，其為眾所皆知的誘變劑和致癌劑。對生態系統而言，氮源的增加也是造成水體優氧化的原因之一。
本研究探討以自行合成之零價奈米級鐵鎳雙金屬(Fe0/ Ni0 )對水體中硝酸鹽之去除效率以及相關動力模式。本研究以批次試驗，針對pH值、不同比例之奈米級零價鐵鎳金屬、硝酸鹽氮起始濃度、溶氧等影響因子對奈米級零價金屬去除硝酸鹽之影響，並據以推算其反應速率常數及半衰期。
研究結果發現不論是奈米鐵、奈米鎳或是奈米級鐵鎳雙金屬，當在低起始pH值時，其對硝酸鹽均有不錯的還原去除效果，並且隨著起始pH值越低其硝酸鹽氮去除效果越好。
在比較奈米級鐵鎳雙金屬與單一奈米鐵及單一奈米鎳金屬對硝酸鹽去除效果時發現，奈米級鐵鎳雙金屬對硝酸鹽去除效果皆優於單一奈米鐵金屬或單一奈米鎳金屬。而溶液中添加不同比例奈米級鐵鎳雙金屬時發現，鐵所佔的比例越高時去除效果越好。
本研究也比較一起合成與分開合成之奈米級鐵鎳雙金屬對硝酸鹽去除之影響，結果發現一起合成之鐵鎳雙金屬對硝酸鹽去除效果皆優於分開合成之鐵鎳雙金屬。
此外，本研究發現水中溶氧高低對奈米級零價金屬去除硝酸鹽並無明顯影響。
關鍵詞：鐵鎳雙金屬、硝酸鹽、奈米鐵、奈米鎳 Nitrate is one of main pollutants in the groundwater. Nitrate, indigested by the digested system, may be converted to nitrites, which could switch the iron in hemoglobin from ferrous to ferric state and make it no longer capable of carring oxygen. Nitrites can react with secondary amines to form N-nitrosamines, which are the well-known mutagen and carcinogen. In addition, the increase of nitrogen can enhance the eutrophication of the water body.
The aim of this study is to realize the removal efficiency and kinetics of nitrates in water treated by nanoscale Fe0/ Ni0. The influences of several factors, including pH, the adding ratio of Fe0 with Ni0, initial nitrate concentration and DO on the reaction of nitrates with nanoscale Fe0/ Ni0 would be operated by batch tests and to find the rate constants and half-life.
Results show that the removal efficiencies of nitrates in the low pH are all significant by adding no matter nanoscale Fe0, Ni0 or Fe0/ Ni0.
Comparing the removal efficiency of nitrates by adding nanoscale Fe0, Ni0 or Fe0/ Ni0, it can be found that the adding of bimetallic Fe0/ Ni0 can get the better removal efficiency than nanoscale Fe0 or Ni0. Meanwhile, the higher of the ratio of Fe0 in bimetallic Fe0/ Ni0 can attain the better removal efficiency on nitrates.
This study is also to compare the removal efficiency of nitrates by adding combinedly or separatedly synthesized nanoscale Fe0/ Ni0. Results show that combinedly synthesized could attain the better removal efficiency on nitrates than separatedly synthesized.
In addition, DO content in water body can not affect the removal of nanoscale zero-valent metals on nitrates.
Keywords: bimetallic iron/nickel, nitrate, naoscale iron, nanoscale nickel.
