規則中孔洞碳材吸附水中尼古丁之研究

Abstract

尼古丁(Nicotine)為一種具有良好水溶性的高毒性植物鹼，因近年來已於都市汙水廠的放流水中被發現而備受關注。且由於目前國內外並無制訂針對尼古丁的放流水標準，隨著大量的尼古丁持續排放到水環境中，勢必會增加人體暴露到尼古丁的風險，但至今仍缺乏針對水中尼古丁的相關處理程序。雖近年來已有研究使用高級氧化處理法，但該方法不僅耗費大量能資源，且可能會產生比尼古丁毒性更高的中間產物，對環境及人體健康衝擊更大。因此，發展一個能有效去除水中尼古丁且低耗能低環境衝擊量的處理技術是目前迫切需要研究的方向。本研究以低溫水熱法製備摻雜奈米鎳金屬顆粒的規則中孔洞碳材(Ordered mesoporous carbon with embedded Nickel, OMC-Ni)作為吸附劑，吸附去除水中的尼古丁，並於反應結束後透過外加磁場進行回收再利用。本研究中，係以SEM、TEM、XRD和BET探討OMC-Ni材料的特性分析，而以界達電位儀與FTIR分析材料表面的帶電性及官能基分佈。而在吸附實驗中，可利用合成之OMC-Ni材料降解尼古丁。在尼古丁初始濃度300μM、吸附反應3小時後，尼古丁在pH=2、6、8.7、10及溫度25度條件下的吸附實驗去除率分別為3.98 %、27.7 %、46.4 %、84.6 %，發現材料對尼古丁的去除率隨著pH值的上升而增加，於pH=10鹼性條件下有最佳的去除率。此外本研究亦結合綠色化學的理念與生命週期評估法，針對有無摻雜鎳金屬的兩種材料(OMC及OMC-Ni)與兩種材料的回收重複利用方式(添加部分新材料及直接重複利用)進行環境友善度評估比較。由LCA結果顯示，OMC-Ni因單位尼古丁去除率較低，故比起OMC有較高的環境衝擊，而回收後添加部分材料的重複利用方式比起直接重複利用有較佳的環境友善度。本研究藉由摻雜鎳金屬顆粒的規則中孔洞碳材作為一可磁性分離的吸附劑，已成功去除水中的尼古丁且可回收再利用，提供一個新型的尼古丁去除技術，並以生命週期評估法作為技術評估與未來改善方向的依據。

Nicotine (3-substituted pyridine, C10H14N2), a highly toxic alkaloid found in municipal wastewater, poses a serious public health concern. Since nicotine effluent standards have yet to be established, large quantities of tobacco waste from cigarette production have led to an increase in nicotine concentration in both underground and surface water flows. However, the technology to treat nicotine contaminated water is lacking. Advanced oxidation processes (AOPs) have been used in recent years, but do not achieve total mineralization of the nicotine, and therefore the toxicity of the intermediates generated, and their evolution during the oxidation process. Therefore, in this study a novel material, ordered mesoporous carbons with embedded metallic nickel nanoparticles (OMC-Ni), was synthesized for improving the adsorption of nicotine. A simple and low temperature (50℃) hydrothermal method was used which made nickel particles homogeneously disperse in the carbon matrices, while the pore mesostructure remained intact. The results can be demonstrated by using XRD, SEM, TEM and BET. The adsorption test results of nicotine removal rate at pH= 2, 6, 8.7, and 10 were 4.0, 27.7, 46.4 and 84.6%, respectively, at an initial 300μM nicotine concentration for 180 min. The adsorption amount of nicotine decreased with decreasing pH of aqueous solution, whereas the adsorption amount tended to increase at basic pH condition. The OMC-Ni composites were demonstrated to be effective molecular adsorbents for magnetic separation. In addition, Life Cycle Assessment (LCA) was used to calculate the environmental impacts of different adsorbents (OMC-Ni and OMC) and repeat methods. The results revealed OMCs have lower energy consumption and are more environmentally friendly than OMC-Ni due to their great removal rate. In the study, we develop a new and successful method for nicotine removal, as well as a life cycle inventory of treatment technology.