利用胺基酸改質鎂鋁層狀複合金屬吸附重金屬之研究

A study on adsorption of heavy metals by Mg-Al LDHs intercalated with amino acids

李威仁(Wei-Jen Lee)

指導教授 ： 趙煥平

中原大學/工學院/生物環境工程研究所/碩士(2016年)

https://doi.org/10.6840/cycu201600582

摘要

本研究利用水熱法合成鎂鋁層狀複合金屬氫氧化物，再利用共沉澱法將苯丙胺酸、酪胺酸、絲胺酸三種胺基酸之有機酸陰離子，插層至鎂鋁層狀複合金屬，並將改質前後之吸附劑吸附溶液中之陰陽離子型重金屬污染物。製備完成之吸附劑利用XPS、SEM、FTIR及XRD鑑定其性質，再利用吸附平衡計算各類重金屬離子之吸附容量並探討可能的吸附機制。
研究結果顯示出，經過有機酸陰離子改質後之苯丙胺酸-LDHs、酪胺酸-LDHs及絲胺酸-LDHs可以迅速的吸附本研究所選定的陽離子型重金屬污染物(銅、鉛、鎘、鎳)及陰離子型污染物(高錳酸鹽)。對於Mg-Al LDHs來說，其表面具有少數氫氧官能基，會和重金屬離子形成不溶於水之金屬氫氧化物，以及其結構分解出的碳酸根離子和重金屬離子形成之金屬碳酸鹽沉澱，而達到之吸附效果；經過有機酸陰離子改質後之苯丙胺酸-LDHs、酪胺酸-LDHs及絲胺酸-LDHs則和重金屬離子產生螯合作用，以錯合反應去除重金屬，進而提升其吸附量。對於重金屬溶液之pH條件下，陽離子型重金屬污染物在pH=5時達到最好吸附效果；陰離子型污染物則是在pH=3時達到最大吸附量。整體吸附劑之效率為：苯丙胺酸-LDHs>酪胺酸-LDHs>絲胺酸-LDHs>Mg-Al LDH，改質前後之最大吸附量可增加2~7倍，不僅對陽離子型重金屬污染物有顯著的吸附效果，且同時可吸附陰離子型污染物。

關鍵字

鎂鋁層狀複合金屬；胺基酸；吸附；陽離子重金屬；含氧陰離子

並列摘要

Mg-Al layered double hydroxides (Mg-Al LDHs) intercalated with the organic acid anions (amino acids) and adsorbed the cationic heavy metals (Cu、Pb、Cd、Ni) and the oxyanion (MnO4-) from aqueous solution have been studied. Mg-Al LDHs was prepared by hydrothermal method and then the amino acids were intercalated using the coprecipitation method to form the phenylalanine Mg-Al LDH, tyrosine Mg-Al LDH and serine Mg-Al LDH as the adsorbents. The adsorbents were characterized by XPS, SEM, FTIR and XRD. The maximum adsorption capacities of adsorbents under the given conditions were estimated from Langmuir equation. The adsorption mechanisms of test adsorbents toward the heavy metal pollutants were examined.
The results indicated that the modified adsorbents could simultaneous adsorb cationic heavy metals and the anionic pollutants. For Mg–Al LDHs, the adsorption capacities mainly result from the surface precipitation. For phenylalanine Mg-Al LDH, tyrosine Mg-Al LDH and serine Mg-Al LDH, the adsorption capacities were mainly attributable to the formation of the phenylalanine–metal, tyrosine–metal and serine–metal complexes in the interlayers of the Mg–Al LDHs, leading to the high adsorption capacities. For the best pH condition of the cationic heavy metals solution during the adsorption will be pH=5 and the anionic pollutants will be pH=3. The uptake of the cationic heavy metals increased in the order to phenylalanine Mg-Al LDH > tyrosine Mg-Al LDH > serine Mg-Al LDH> Mg-Al LDH. The modified adsorbents offered more than 2~7 times higher adsorption capacities, not only for the cationic heavy metals but also to the anionic pollutants.

並列關鍵字

Mg-Al layered double hydroxide ； Amino acids ； Adsorption ； Cationic heavy metals ； Oxyanion

參考文獻

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