| 摘要: | 台灣從早期的工業化時代至現，在經濟成長的同時也衍生出許多環境污染事件，其中以重金屬污染最為普遍。重金屬的鉻是常見的污染物之一，對人體而言亦是致癌物質的一種。
近年來許多零價金屬處理地下水中污染技術被發表，製備奈米顆粒技術開始應用在零價金屬上，有效提高處理效果並減少藥劑的使用量，減少對環境的衝擊。
本研究選擇易取得之鐵、銅、鎳金屬，應用化學還原法，以離子態金屬溶液，添加硼氫化鈉為強還原劑之溶液進行還原，合成出奈米級零價金屬顆粒。目的是在以批次實驗方式進行研究過程中，利用奈米金屬強大的還原能力來處理水中六價鉻，並探討在不同起始濃度、不同起始pH值、不同金屬配比組合的反應條件下，處理水中六價鉻的最佳條件。
本研究的批次試驗中以不同組合之奈米零價金屬（Fe0、Cu0、Ni0、Fe0/Cu0、Fe0/Ni0、Cu0/Ni0、Fe0/Cu0/Ni0）對六價鉻去除效果作比較，在分別控制不同起始pH値（3、4、5）的條件下，發現pH値越低對六價鉻去除效果越好，且奈米零價三金屬對六價鉻去除效果優於奈米零價單金屬和奈米零價鐵銅雙金屬。
而在探討最佳金屬配比組合方面，實驗結果發現奈米零價雙金屬中以奈米零價鐵銅雙金屬對六價鉻去除效果最佳，其最佳配比為95/5；於最佳奈米零價三金屬試驗中發現，奈米零價鐵銅鎳三金屬對六價鉻去除效果最佳，其最佳配比為99/1/0.1。
Taiwan, from the early industrialization period until now, has produced enormous amounts of pollutions, especially, heavy metal pollution. Chromium is a common heavy metal pollutant and found to be human carcinogens.
Recently, many researches used zero-valent metals in groundwater pollution remediation. Moreover, nano-particle technology was also applied for producing zero-valent metals, which can increase the effective of zero-valent metals, reduce the amount of agents used, and reduce the impact on environment.
In this study, iron, copper and nickel were prepared by chemical reduction method.Sodium borohydride, which is a strong reducer agent, was then added into the solution for the reduction and synthesis of nanoscale zero-valent metal particals.This experiment aimed to study the ability of nanoscale zero-valent metal particals on the removal of hexavalent chromium in wastewater. Effects of fresh hexavalent chromium concentrations, fresh pH values and metal composition ratios were examined to identify the optimal condition for removing hexavalent chromium from wastewater. All experiments were carried out in batch mode.
Different combinations of nanoscale zero-valent metal particals (Fe0、Cu0、Ni0、Fe0/Cu0、Fe0/Ni0、Cu0/Ni0、Fe0/Cu0/Ni0) was compared on hexavalent chromium removal efficiency. Fresh pH values (3, 4, 5) were also identified and it was found that low pH value showed higher hexavalent chromium removal efficiency than high pH value. Moreover, results indicated that nanoscale zero-valent trimetallics have higher removal effieincy than nanoscale zero-valent bimetallics and nanoscale zero-valent metals, respectively.
For metal composition ratios, experiments revealed that nanoscale zero-valent bimetallics (Fe0/Cu0) at the optimum ratio of 95/5 yielded higher hexavalent chromium removal efficiency than other nanoscale zero-valent bimetallics. However, the highest removal efficiency of hexavalent chromium was found when nanoscale zero-valent trimetallics
(Fe0/ Cu0/ Ni0) at the optimum ratio 99/1/0.1 was applied. |
