多壁奈米碳管／環氧樹脂碳化複合材料對二價銅離子吸附能力研究

Cu(II) adsorption by carbonized multi-walled carbon nanotubes/epoxy composites

魏伯諭(Po-Yu Wei)

指導教授 ： 徐文光

國立清華大學/工學院/材料科學工程學系/碩士(2012年)

摘要

本研究以簡單的方式製作多壁奈米碳管複合物，成功地去除溶液中的二價銅離子(Cu2+)，同時解決奈米碳管難以回收的缺點。
　　三種比例之多壁奈米碳管(MWCNTs)混合環氧樹脂(Epoxy resin)後再經碳化(Carbonization)和酸化(Acidification)改質步驟，用來吸附溶液中二價銅離子。吸附實驗分為兩部分：以粉末狀樣品做吸附；另一部分是使用薄板狀樣品以電容去離子技術(capacitive deionization, CDI)去除溶液中Cu(II)。同時量測樣品各種性質，探討比表面積、平均孔徑、電阻率、石墨化程度、表面形貌和官能基與吸附效率之間的關係。
　　結果顯示，樣品經過酸化步驟，樣品電阻率大幅下降；比表面積下降；平均孔徑提升；極性官能基增加，使樣品由疏水性轉為親水性。粉末狀樣品以Langmuir等溫吸附模型估算其最大吸附容量為19.49 mg•g-1，而吸附現象較符合Freundlich模型。粉末樣品經過酸洗可重複利用。薄片樣品在施加1.2 V偏壓下，吸附容量可提升約3.5倍。溶液濃度低時，Cu(II)之去除機制為電雙層吸附及官能基離子交換；高濃度時，機制為電解硫酸銅溶液。經過再生步驟之薄板狀樣品，去除Cu(II)能力皆相近，但僅為初次使用之樣品的80 %左右。

關鍵字

多壁奈米碳管 ； 環氧樹脂 ； 吸附 ； 二價銅離子 ； 電容去離子法

並列摘要

Carbonized multi-walled carbon nanotubes/epxoy composites are made to absorb Cu2+ in aqueous solution and CNTs are found retrievable after repeated experiments.
Carbonized composites, consisting of multi-walled carbon nanotubes and epoxy resin in different ratios, are used to remove copper ions in the solution after carbonization and acidification processes. Adsorptive experiments are divided into two parts; first, the samples powdered and are used as Adsorbents; second, samples are made as thin films and ionic absorption is carried out using CDI technology. Samples are also characterized in order to establish the relationship between sample structure and chemical treatments.
Results show that acidification decreases resistivity of powdered samples and specific surface area whereas porosity and density of functional groups increase. Accordingly, samples change from hydrophobic into hydrophilic property and the maximum adsorption capacity of Cu(II) calculated by Langmuir model reaches 19.49 mg•g-1, fit better with Freundlich model than that of Langmuir model. Samples can be reused through regeneration procedure. In CDI adsorption experiment, the adsorption capacity of film samples increases by three-fold at applied 1.2 V between electrodes. The adsorption mechanism is found as a result of combined electrosorption and ion exchange at low concentration situation. At high concentration, adsorption of copper(II) sulfate proceeds through electrolysis and amount of removed ions from solution decreases to 80 % at the 1st run. Absorption curves become stabilized after the 1st regeneration process.

並列關鍵字

Carbon nanotubes ； Epoxy ； Adsorption ； Cu(II) ； Capacitive deionization

參考文獻

[41] 中華民國行政院環境保護署，水污染防治法－放流水標準，2011年。

[1] C.L. Chen, J. Hu, D.D. Shao, J.X. Li and X.K. Wang, Adsorption behavior of multiwall carbon nanotube/iron oxide magnetic composites for Ni(II) and Sr(II), J. Hazard. Mater. 164 (2009) 923-928.

[2] R.Q. Long and R.T. Yang, Carbon nanotubes as a superior sorbent for nitrogen oxides, Ind. Eng. Chem. Res. 40 (2001) 4288-4291.

[3] R.Q. Long and R.T. Yang, Carbon nanotubes as superior sorbent for dioxin removal, J. Am. Chem. Soc. 123 (2001) 2058-2059.

[4] S. Agnihotri, M.J. Rood and M. Rostam-Abadi, Adsorption equilibrium of organic vapors on single-walled carbon nanotubes, Carbon 43 (2005) 2379-2388.