利用鈣礬石去除水中亞甲基藍、鉻酸鹽及銅之研究

Removal of methylene blue, chromate and Cu from water through Ettringite

黃培熏(Pei-Hsun Huang)

指導教授 ： 趙煥平

中原大學/工學院/環境工程學系/碩士(2021年)

https://doi.org/10.6840/cycu202100450

摘要

鈣礬石是一種在水泥中含有的礦物，其結構含有的Ca2+及Al3+可以被廢水中的二價陽離子及三價陽離子所取代，結構中的SO42-亦可以被陰離子所取代，因此本研究是利用鈣礬石去除水中陽離子染劑、陰離子重金屬及陽離子重金屬，並計算鈣礬石對於各個污染物的最大吸附容量以及討論吸附機制。
經共沉澱法製成鈣礬石後利用FTIR、XRD、Zeta Potential、SEM及BET了解鈣礬石的基本性質，然後在不同pH值條件下進行平衡吸附實驗，並以Langmuir方程式估算對亞甲基藍、鉻酸鹽與銅離子之最大吸附容量，以及利用不同初始濃度進行動態吸附實驗研究結果顯示，並以擬一階、擬二階與顆粒內擴散模式測試其符合度。
實驗結果顯示，所合成吸附劑之零電位點在pH 8.6，對亞甲基藍之最大吸附量666 mg/g；吸附鉻酸鹽及銅離子的最大吸附量則分別為75.2 mg/g與476 mg/g；動態吸附較符合擬二階模式，吸附機制主要為離子交換，部分銅離子可能因沉澱去除，亞甲基藍則可能有氫鍵作用或其他去除機制。

關鍵字

鈣礬石、亞甲基藍、鉻酸鹽、銅離子、吸附

並列摘要

Ettringite is a hydrous calcium aluminium sulfate mineral existing in cement. The chemical composition of Ca2+ and Al3+ in ettringite could be replaced by other divalent and trivalent cations. In addition, the composition of SO42- can be replaced with other anions. In this study, ettringite is used to uptake cationic dye, cationic heavy metal ion and oxyanion. Then, the adsorption capacities of the selected contaminants were estimated, and the adsorption mechanisms were evaluated.
Ettringite is synthesized through a co-precipitation method. The sample was characterized by FTIR, XRD, zeta potential, SEM and BET surface area. The adsorption experiments were carried out in various pH solutions. The adsorption capacities of contaminants including copper ion, methylene blue and chromate in equilibrium adsorption were estimated using Langmuir equation. The kinetic adsorption was carried out using the two initial concentrations. The pseudo-first-order, pseudo-second-order and intraparticle diffusion models were applies to fit the data.
The results of ettringite showed the point of zero charge is pH 8.6. The adsorption capacity of methylene blue is 666 mg/g. The adsorption capacity of chromate and copper ions are 75.2 mg/g and 476 mg/g, respectively. The kinetic adsorption can fit the pseudo-second-order model well. Ion exchange was regarded as the primary adsorption mechanism. The adsorption mechanisms of methylene blue involve hydrogen bonding and others.

並列關鍵字

Ettringite, methylene blue, chromate, copper ions, adsorption

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