奈米碳管對硝基酚與銅混合溶液其吸附機制之探討;Adsorption mechanism of nitrophenol and copper(II) from mixed liquor by mult-walled carbon nanotubes

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Title:	奈米碳管對硝基酚與銅混合溶液其吸附機制之探討;Adsorption mechanism of nitrophenol and copper(II) from mixed liquor by mult-walled carbon nanotubes
Authors:	蘇建智;Su,Jian-zhi
Contributors:	環境工程研究所
Keywords:	協同效應;競爭吸附;循環伏安法;synergistic effect;competitive adsorption;cyclic voltammetry
Date:	2014-07-25
Issue Date:	2014-10-15 17:25:59 (UTC+8)
Publisher:	國立中央大學
Abstract:	本研究利用多壁奈米碳管吸附硝基酚異構物(2-NP 與 4-NP) 及Cu(II) 的混合溶液以探究其吸附機制，以及硝基酚與Cu(II) 之間的關係。利用批次吸附實驗與電化學實驗這兩種實驗方法的結果來相互比較與解釋論述。批次吸付實驗結果顯示，混合系統為酸性條件時，NPs 可能因苯環和含氧官能基之間的作用力而不容易靠近碳管表面，Cu2+則較NPs 容易靠近碳管表面。也可能是Cu2+可能與水形成水合作用，產生遮蔽效應，這些都將不利於NPs 吸附於碳管表面，所以可以推測碳管對NPs 與Cu2+的吸附，可能存在著相互競爭的關係。混合系統為鹼性條件時，碳管對於2-NP 與Cu2+ 的吸附百分比均有明顯增加的現象，但對4-NP 的吸附百分比並沒有像 2-NP 的結果一樣顯著增加。結合循環伏安掃描結果可推測有三種可能的吸附機制：(A) 2-NP 可能與銅離子形成新物質而吸附於碳管表面；(B) 碳管可能是先吸附Cu2+而硝基酚負離子再藉由靜電吸引力吸附在Cu2+上；(C) 沉澱物之影響。至於當4-NP 與Cu2+的混合系統為鹼性條件時，推測其吸附機制可能是碳管先吸附Cu2+而硝基酚負離子再藉由靜電吸引力吸附在 Cu2+上。此外，在電化學方面發現了後加入Cu2+的系統中，4-NP 的電流值在加入Cu2+後有增加的趨勢，而Cu2+的電流值明顯小於4-NP 的電流值，藉此可以做個推測，表示在此實驗中Cu2+會幫助4-NP 對於奈米碳管修飾電極發生更佳的反應，而且4-NP 比Cu2+對於奈米碳管修飾電極具有更佳的反應。;The objective of this thesis is to explorethe mechanismof baniry adsorption of Nitrophenol and Cu(II) by MWCNTs.Batch adsorption and cyclic voltammetry were conducted and compared. It is suggested that it would be difficult for NPs to get close to the surface of MWCNTs because of the interactions between the benzene ringof NPs and the oxygen-containing in acidic condition. It is also believed that the hydrationofCu2+limited the adsorption of NPs. In this case, it can be speculated that there is competition between NPs and Cu2+for the adsorption on fthe MWCNTs.On the other hand, in alkaline solution, an apparent increase in theadsorption of 2-NP was found while such increase was not observed for 4-NP. Threeadsorption mechanisms may be possible: (A) 2-NP and Cu2+may form a new compounds,(B) MWCNT may adsorb Cu2+first, followed by the adsorption of dissociated nitrophenol ionsdue to the electrostatic attraction withCu2+, and (C) Surface precipitation of Cu may decrease the negative charges of the MWCNTs surface.For 4-NP and copper are mixed in alkaline solution, Cu2+ may be adsorbed on the MWCNTs first followed by the adsorption of 4-NP.From CV, it was found that the current of 4-NP increased after Cu2+was added in the solution. Meanwhile, the current of Cu2+ became weaker than that of 4-NP. Therefore, it can be suggested that the presence of Cu2+may enhance the adosprtion of 4-NP onMWCNT.
Appears in Collections:	[Graduate Institute of Environmental Engineering ] Electronic Thesis & Dissertation

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