- 學位論文
十六烷基三甲基溴化胺改質吸附劑用於去除水中重金屬之探討
Adsorption of heavy metals on various adsorbents modified by hexadecytrimethylammouium bromide
摘要
本研究主要在討論以十六烷基三甲基溴化胺離子(HDTMA)改質Y沸石、蒙特石及奈米鈦酸鹽管，並在單一及混合系統下針對陰、陽離子進行吸附，藉由吸附等溫線所得之結果，探討吸附劑改質前後對金屬離子之作用機制與吸附容量。 經HDTMA改質前後之Y沸石、蒙特石及奈米鈦酸鹽管，利用SEM、BET、元素分析儀、界達電位及陽離子交換容量，鑑定吸附劑之性質。本實驗所使用的重金屬分兩類，第一類為陽離子金屬包括銅、鎳、鉛、鋅、鎘、鉻及錳等七種，第二類為陰離子金屬包括重鉻酸鹽及高錳酸鹽。 結果顯示改質後吸附劑表面積、孔徑與孔隙體積均將減少，懷疑可能為HDTMA遮住部分小孔洞，改質後的吸附劑因HDTMA聚集形成雙層結構導致表面帶正電而可吸附陰離子金屬，另因HDTMA無法進入吸附劑之小孔洞中使孔洞內部維持陽離子交換位置，改質後的吸附劑可同時吸附陽離子與陰離子重金屬而使吸附劑成為雙親性之吸附劑。在競爭吸附下，吸附陽離子金屬之親合力順序可參考金屬離子半徑，但會受到金屬價數、pH值及吸附劑性質之影響，吸附效果可參照吸附劑之陽離子交換容量大小做為依據。
並列摘要
The objective of this study is to develop new adsorbents that can uptake both cationic metals and anionic metals. Three kinds of raw materials, Y zeolite, montmorillonite and titanate nanotube, modified by hexadecytrimethylammouium bromide (HDTMA) were selected as the target adsorbents. The cationic metals including copper, nickel, lead, zinc, cadmium, chromium and manganese, and the anionic metals including dichromate and permanganate were used to examine the mechanism and the adsorption capacity of adsorbates relative to synthesized adsorbents. In order to understand surface characteristics of the synthesized adsorbents, the raw and the modified adsorbent were analyzed using SEM, BET, elemental analysis, zeta potential, and cation exchange capacity. The adsorption experiments were divided into two parts. One is individual metal ion absorbs on the adsorbents to obtain the adsorption capacity. The other is more than two metal ions absorb the adsorbents to discuss competitive sites. The results showed that the modified adsorbents possess the lower surface area, pore size and pore volume, which is assumed that HDTMA can cover the small pore. In addition, HDTMA potentially aggregates on the adsorbent surface to form two- layer structure with positive charge. This can lead to anionic metal adsorbing on modified adsorbents via ion exchange. On the other hand, the adsorbed HDTMA cannot enter the small pores, which causes the internal pores maintain cation exchange sites. Thus, the modified adsorbents can absorb the heavy metal cations and anions. In competitive adsorption, the radius of metal ions for the cationic metal is a dominant factor. However, oxidation states, pH and adsorbents affect the adsorption capacity.