奈米鐵主要將硝酸根轉化成氨離子，而高濃度氨對水域生態具有毒害性。然而，如果對零價鐵做一稍微的修正，可以選擇型性地將硝酸根還原成一種無毒害性的最終產物氮氣。本研究藉著其它奈米金屬 (例如：銅、鈀)與零價鐵混和形成三金屬：Cu(促進性金屬)–Fe0(還原性金屬)–Pd(貴重金屬)，以改善硝酸根轉換成氮氣之效率。實驗結果顯示，當鈀、銅分使用量別為1%及4%時，氮氣生成效率為25%，最大硝酸根去除率則為90%。 Nanoscale zero-valent iron (nZVI) predominantly converts nitrate to ammonium ions, a toxic substance to aquatic ecosystem at elevated concentration. However, slight modification of nZVI would enable the selectivity of reducing nitrate into nitrogen gas which is the desired harmless end-product. The improvement of nitrate conversion to nitrogen gas was investigated in this study by the doped nZVI. Trimetal such as nZVI doped with nanometallic catalysts Cu and Pd, Cu(promoting metal)–Fe0(reducing metal)–Pd(noble metal), was used to enhance nitrogen gas formation, with various weight percent of Pd and Cu. The results show that the most nitrogen gas selectivity of around 25% occurred when 1% Pd and 4% Cu were applied, and the maximum nitrate removal is 90%.