外表面積和靜電相互作用機理對MOFs染料吸附的重要性;The Importance of External Surface Area and Electrostatic Interaction Mechanism to Dye Adsorption on MOFs

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題名:	外表面積和靜電相互作用機理對MOFs染料吸附的重要性;The Importance of External Surface Area and Electrostatic Interaction Mechanism to Dye Adsorption on MOFs
作者:	陳霸綸;Luan, Tran Ba
貢獻者:	化學工程與材料工程學系
關鍵詞:	ZIF-8;UiO-66;染料吸附;外表面積;靜電吸引力;ZIF-8;UiO-66;Dye adsorption;External surface area;Electrostatic attraction
日期:	2019-01-04
上傳時間:	2019-04-02 14:13:41 (UTC+8)
出版者:	國立中央大學
摘要:	由化學計量金屬配位體前趨溶液經超聲輔助水熱反應製備了兩種ZIF-8晶體，與未添加表面活性劑的ZIF-8相比，表面活性劑的添加促進形成具有大外表面積的奈米晶體，然後使用這兩個樣品檢查粒度對染料吸附的影響，發現羅丹明B（RB）和甲基橙（MO）的吸附容量與ZIF-8顆粒的外表面積成正比，而亞甲藍（MB）的吸附容量則不隨外表面積減小而消失。我們的計算表明，每個RB和MO分子分別佔據外表面積的4.7和7.9 nm2，相反地，在每單位晶胞有0.11個分子以及每分子具有2.3nm2的外表面積情況下，MB吸附發生在ZIF-8結構內部。在本論文的第二部分，研究了靜電吸引機制在染料吸附中對UiO-66及其改質樣品的影響，在正常的攪拌和加熱條件下製備Co / UiO-66和H+ / UiO-66樣品以增加表面上的正電荷，並用XRD、SEM和FTIR指出在UiO-66上存在質子H+，而拉曼光譜、EPR和ICP-MS證實鈷成功摻雜約0.6 wt％到UiO-66結構中。甲基橙（MO）吸附的結果表明，與原本的UiO-66相比，改質後的Co-UiO-66和H+ / UiO-66的表面增強了吸附能力，此外，對於在MO與MB的混合染料溶液下詳細地進行了實驗，發現去除陰離子染料相比去除陽離子染料具有更高的選擇率，指出靜電吸引機制的重要性。一般而言，靜電吸引機制和外表面積在MOF上的染料吸附中起重要作用，由於MOF的特殊結構，突出了與該領域中傳統吸附劑的差異，如同上面所敘述，ZIF-8是一種可變動的骨架，造成它對於染料進入結構時具有選擇性，此外，靜電引力對UiO-66和ZIF-8上的染料吸附也是主要作用之一。 ;Two kinds of ZIF-8 crystals have been prepared from the ultrasound-assisted hydrothermal reaction of a stoichiometric metal-ligand precursor solution. The addition of surfactant promoted the formation of nanocrystals having a much larger external surface area compared to the non-promoted one. The two samples were then employed to examine the effects of particle size on dye adsorption. The adsorption capacity of Rhodamine B (RB) and methyl orange (MO) was found to be directly proportional to the external surface area of the ZIF-8 particles, while that of methylene blue (MB) did not vanish with decreasing external area. Our calculations suggested that each RB and MO molecule occupied 4.7 and 7.9 nm2 of the external surface, respectively. In contrast, MB adsorption occurs both inside the ZIF-8 structure, at a loading of 0.11 molecules per unit cell, and on the external surface with 2.3 nm2/molecule. In the second part of this thesis, the effect of electrostatic attraction mechanism in dye adsorption on UiO-66 and their modified samples was studied. Two samples of Co/UiO-66 and H+/UiO-66 were prepared under normal stirring and heating conditions to increase the positive charge on the surface. Characterization with XRD, SEM, and FTIR indicated the existence of proton H+ on UiO-66, while Raman spectroscopy, EPR, and ICP-MS confirmed the successful doping of cobalt into the UiO-66 structure at about 0.6 wt%. Results from methyl orange (MO) adsorption indicate surface enhanced adsorption capacity for both Co-UiO-66 and H+/UiO-66 compared to parent UiO-66. Moreover, highly selective removal of anionic dye compared to cationic dye were performed in detail for mixed dye solutions of MO with MB, indicating the important role of electrostatic attraction mechanism. In general, the electrostatic attraction mechanism and external surface area play important roles in dye adsorption on MOFs, highlighting differences compared to traditional adsorbents in this field due to the special structure of MOFs. ZIF-8 is a flexible framework which showed selectivity for dye entering the structure as commented above. Also, the electrostatic attraction plays as a major contribution to dye adsorption on both UiO-66 and ZIF-8.
顯示於類別:	[化學工程與材料工程研究所] 博碩士論文

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