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    Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/53920

    Title: 奈米碳管對於硝基酚與銅之競爭吸附;Competitive adsorption of nitrophenol and copper(II) from aqueous solutions on mult-walled carbon nanotubes
    Authors: 李向曦;Lee,Hsiang-hsi
    Contributors: 環境工程研究所
    Keywords: Polanyi model;Langmuir model;競爭吸附;competitive adsorption;Polanyi model;Langmuir model
    Date: 2012-07-30
    Issue Date: 2012-09-11 18:19:14 (UTC+8)
    Publisher: 國立中央大學
    Abstract: 本研究利用奈米碳管吸附鄰-硝基苯酚(2-NP)、對-硝基苯酚(4-NP)及銅離子(Cu2+),探討其競爭吸附及機制。研究結果顯示,經硝酸氧化處理後,比表面積與氧化前差異不大,但在碳管表面引入官能基-COOH,使得碳管表面電荷有所改變,造成對2-NP、4-NP及Cu2+的吸附影響。等溫吸附實驗顯示,碳管的含氧官能基多寡會影響2-NP、4-NP及Cu2+之吸附量,未經氧化奈米碳管吸附2-NP及4-NP之吸附量會優於氧化後奈米碳管,和空間障礙及水簇作用有關。而氧化後奈米碳管對吸附Cu2+之吸附量會大於未氧化碳管,會因官能基的增加提高碳管表面負電荷,導致吸附量提高。2-NP與4-NP因電子分佈之影響,氧化前後奈米碳管對4-NP的吸附能力較2-NP低;不論酸氧化前後奈米碳管,對於2-NP及Cu2+之吸附皆較為符合Langmuir模式,而對於4-NP之吸附則較為符合polanyi 模式。經熱力學分析得知酸氧化前後奈米碳管吸附2-NP及4-NP均為放熱反應;而酸氧化前後奈米碳管吸附Cu2+為吸熱反應。在不同pH值下,酸氧化後奈米碳管吸附2-NP及4-NP之吸附量具有相同的趨勢,與分子解離及表面電荷有關;吸附Cu2+則與表面電荷及沉澱有關。在2-NP及4-NP存在下之競爭結果顯示,碳管吸附Cu2+之吸附量增加,因2-NP及4-NP解離後將可能與Cu2+形成新物質或錯合物,提高Cu2+之吸附百分比;但在pH值小於7時,Cu2+將對氧化後奈米碳管吸附2-NP及4-NP產生抑制作用,與水合作用產生遮蔽效應有關。Adsorption of 2-nitrophenol (2-NP), 4-nitrophenol (4-NP), and copper (Cu2+) by multi-walled carbon nanotubes (MWCNTs) with and without oxidation by nitric acid were investigated in this study. The adsorption capacities of 2-NP and 4-NP by A-MWCNT were larger than H-MWCNT, because of steric obstructions and water clustering. On the other hand, H-MWCNT had better adsorption capacity of Cu2+ than A-MWCNT, because the functional groups generated more negatively charged surface. Furthermore, MWCNTs had better adsorption capacity of 2-NP than 4-NP due to the electronic distribution. The adsorption of 2-NP and 4-NP by MWCNTs were endothermic while the adsorption of Cu2+ was exothermic. The enthalpy change and free energy change suggested that the adsorption of 2-NP, 4-NP, and Cu2+ onto MWCNTs were physisorptions. The adsorption at different pH values showed that the adsorption of 2-NP and 4-NP by H-MWCNT had the same trend, relating to the molecular dissociation and surface charge, while the adsorption of Cu2+ was affected by the surface charge and precipitation. When 2-NP or 4-NP were present, the adsorption of Cu2+ was promoted, because complexes of 2-NP/Cu and 4-NP/Cu may form after 2- and 4-NP dissociated. When pH values were lower than 7, the adsorption of 2-NP and 4-NP would be inhibited by Cu2+ due to the shielding from hydration of Cu2+.
    Appears in Collections:[環境工程研究所 ] 博碩士論文

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