利用有機含硫鹽改質鎂鋁層狀複合金屬氫氧化物吸附重金屬之研究

A study on adsorption of heavy metals by Mg-Al LDHs intercalated with organic solutes containing sulfur

劉晉廷(Jin-Ting Liu)

指導教授 ： 趙煥平

中原大學/工學院/環境工程學系/碩士(2017年)

https://doi.org/10.6840/cycu201700577

摘要

本研究利用水熱法合成鎂鋁層狀複合金屬氫氧化物，另外利用共沉澱法將乙基黃原酸鉀、十二烷基硫酸鈉、半胱胺酸三種有機含硫鹽陰離子，插層至鎂鋁層狀複合金屬氫氧化物，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、XRD及BET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，經過有機鹽陰離子改質後之乙基黃原酸-LDHs、十二烷基硫酸鹽-LDHs及半胱胺酸-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(過錳酸鹽)。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，以及層間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；經過有機陰離子改質後之乙基黃原酸-LDHs、十二烷基硫酸鹽-LDHs及半胱胺酸-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，大多陽離子型重金屬污染物在pH=5時達到最好吸附效果；過錳酸鹽則是在pH=4時達到最大吸附量。改質後整體吸附劑之效率為：十二烷基硫酸鹽-LDHs >乙基黃原酸-LDHs >半胱胺酸-LDHs > Mg-Al LDH，改質前後之最大吸附量可增加2~6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

鎂鋁層狀複合金屬氫氧化物 ； 有機含硫鹽類 ； 吸附 ； 陽離子重金屬 ； 含氧陰離子

並列摘要

The adsorption of the cationic heavy metals (Cu、Pb、Cd、Ni) and the oxyanion (MnO4-) on Mg-Al layered double hydroxides (Mg-Al LDHs) intercalated with the organic solutes containing sulfur from aqueous solution have been studied. Mg-Al LDHs was prepared by hydrothermal method and then the organic acids were used to intercalate Mg-Al LDHs through a coprecipitation method to form the adsorbents of DS·Mg-Al LDHs, Ethyl xanthate·Mg-Al LDHs and L-cysteine·Mg-Al LDHs. The adsorbents were characterized by XPS, SEM, FTIR, XRD and BET. 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 ions were examined.
The results indicated that the modified adsorbents could simultaneous adsorb cationic and the anionic heavy metal ions. For Mg–Al LDHs, the adsorption capacities mainly result from the surface precipitation. For·Mg-Al LDHs, Ethyl xanthate·Mg-Al LDHs and L-cysteine·Mg-Al LDHs, the adsorption capacities were mainly attributable to the formation of the DS–metal, Ethyl xanthate–metal and L-cysteine–metal complexes in the interlayers of the Mg–Al LDHs, leading to the high adsorption capacities. The best solution pH values for adsorption of the cationic and anionic heavy metal on adsorbents were pH=5 and pH=4, respectively. The uptake of the cationic heavy metals increased in the order to DS·Mg-Al LDHs > Ethyl xanthate·Mg-Al LDHs > L-cysteine·Mg-Al LDHs> Mg-Al LDHs. The modified adsorbents offered more than 2~6 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 ； Organic solutes containing sulfur ； Adsorption ； Cationic heavy metals ； Oxyanion

參考文獻

40. 張丞笉, 利用生物吸附劑動態吸附水溶液中重金屬. 中原大學土木工程學系 碩士學位論文, 2011.

44. 李威仁, 利用胺基酸改質鎂鋁層狀複合金屬吸附重金屬之研究. 中原大學環境工程學系 碩士學位論文, 2016.

1. F. Cavani, F. Trifirb, A. Vaccari, Hydrotalcite-type anionic clays:preparation, properties and applications. Catal. Today 1991. 11: p. 173-301.

2. K. H. Goh, T. T. Lim, Z. Dong, Application of layered double hydroxides for removal of oxyanions: a review. Water Research, 2008. 42(6-7): p. 1343-68.

3. F. L. Theiss, G. A. Ayoko, R. L. Frost, Synthesis of layered double hydroxides containing Mg2+ , Zn2+ , Ca2+ and Al3+ layer cations by co-precipitation methods—A review. Applied Surface Science, 2016. 383: p. 200-213.