EPA-96-U1U1-02-103

096

1,810 千元

2007/06/04

2008/03/31

董瑞安

永續發展室(停用)

吳婉怡

清華大學生醫工程與環境科學系

水質保護

功能性一維奈米複合材料,鈦酸鹽奈米管,奈米碳管,有機物,重金屬,共處理

Functionalized 1-dimensional nanomaterials, titanate nanotubes (TNT), carbon nanotubes (CNT), refractory organics, heavy metals, coupled removal

張淑閔

radoong@mx.nthu.edu.tw

本研究的主要目的在於藉由奈米碳管純化配合鈦酸鹽奈米管的合成，配製成具有高面向比與高比表面積的功能性一維奈米複合材料，並將之應用於共處理受污環境中的難分解有機污染物與重金屬，同時探討複合材料在水體環境中可能的流佈與宿命反應。研究發現利用鹼性水熱法所配製的鈦酸鹽奈米材料結構，會隨著水熱法加熱溫度的升高，依序由奈米顆粒/奈米薄片轉變為奈米管、奈米線，最後變成奈米緞帶結構。在10 M NaOH溶液中，以120C反應72 小時，可將ST-01二氧化鈦奈米顆粒轉換成表面積大於350 m2/g的一維鈦酸鹽奈米管結構。經後續300 C鍛燒處理4小時後，TNT開始進行晶相轉變，產生二氧化鈦顆粒，但仍保有管狀結構與高比表面積，適合作為光催化材料。而添加不同比例的改質奈米碳管於鈦酸鹽奈米管中除會增加複合材料的比表面積外，也會造成表面-COOH及-C=O官能基的增加，進而改變奈米材料的表面酸度與親水性。 不同配比之CNT/TNT複合奈米材料對重金屬有相當優異的吸附能力，其吸附量依循Pb2+ > Cu2+ ~ Cd2+ > As5+ 的順序，Pb2+及 Cu2+的Langmuir飽和吸附量介於192-588 mg/g及83-204 mg/g間，優於改質後CNT的吸附量。而在不同CNT/TNT配比的吸附上，7.5及20 wt% CNT/TNT複合材料表面有較多的官能基含量，因此對重金屬的吸附能力略優於其他配比之複合材料，但在有機物的吸附能力上，純TNT及CNT對偶氮染料MX5B及estrone的吸附量則優於CNT/TNT複合材料，連帶也影響對有機物的光催化效果，但TNT對MX5B及estrone的光催化效果仍優於P-25及ST-01奈米顆粒。 利用所開發奈米材料進行偶氮染料與重金屬的共處理時，發現Pb會抑制MX5B的吸附量，而Cu的存在則會增加MX5B在CNT/TNT複合材料的吸附量，同時2-10 mg/L的Cu濃度更可增加偶氮染料的光催化速率，顯示所開發CNT/TNT複合材料在適當環境中可進行重金屬與偶氮染料的共處理。而奈米材料在水體環境中的穩定性則受到pH值、陽離子種類濃度及溶解性有機物的影響，溶解性有機物會雖會穩定水體中奈米材料，但當水體 pH值接近奈米材料等電位點時，容易造成奈米材料的團聚，不僅降低其比表面積，也增加奈米材料在水體環境中的沈降性。

功能性一維奈米複合材料,鈦酸鹽奈米管,奈米碳管,有機物,重金屬,共處理

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[期末報告]公開完整版

2008/6/1 上午 12:00:00

The purpose of this project was to fabricate the 1-dimensional nanocomposite materials with high aspect ratios and specific surface areas for the coupled degradation of refractory organic compounds and heavy metals. The 1-dimensional nanomaterials were composed of various ratios of carbon nanotubes (CNT) and titanate nanotubes (TNT) (CNT/TNT) ranging from 2.5 and 20 wt %, and alkaline hydrothermal method was used to fabricate TNT under different hydrothermal conditions. Three different TiO2 raw materials, Degussa P-25, ST-01 and sol-gel-derived TiO2 particles, serving as the starting materials, were added in 3-10 M NaOH solution at hydrothermal temperature of 60-230 C for 1-3 d using pressure bomb system. The morphology changed from nanoparticles/nanosheets, nanotubes, nanowires and then to nanoribbon as the hydrothermal temperatures increased from 60 to 230 C. ST-01 has a relatively high reactivity than those of P-25 and sol-gel-derived TiO2 nanoparticles to form high specific surface area (> 350 m2/g) nanostructured materials at 120 C for 72 h in 10 M NaOH solutions. Post heat treatment at 300 C for 4 h would produce anatase phase of TiO2, and subsequently enhanced the photoactivity of TNT. In addition, the combination of CNT with TNT at 2.5-20 wt% would increase the carboxylic and carbonyl functional groups on surfaces, resulting in the change in surface acidity and hydrophobilicity of composite nanomaterials. The composite CNT/TNT nanomaterials have a good capability toward heavy metal adsorption and the adsorption followed the order Pb2+ > Cu2+ ~ Cd2+ > As5+. The Langmurian maximum adsorption capabilities of nanomaterials were in the range 83-204 mg/g for Cu2+ and 192-588 mg/g for Pb2+, which is superior to that of CNT. The CNT/TNT ratios at 7.5 and 20 wt% have high ability towards heavy metal adsorption, presumably due to the higher amounts of carboxylic and carbonyl functional groups on surfaces. In addition, the adsorption ability of azo dye and estrone using post-heat-treated TNT or acidified CNT is better than those of composite CNT/TNT materials. Good photodegradation efficiencies of MX5B and estrone by TNT were observed, and the pseudo-first-order rate constants for MX5B and estrone photodegradation using TNT were 0.088 and 0.0818 min-1, respective, which are better than those of P-25 and ST-01 TiO2. The aquatic chemistry has a great effect on the coupled removal of pollutants as well as the stability of nanomaterials in solution. The adsorption of MX5B using 7.5 wt% CNT/TNT was inhibited by the addition of Pb2+. In the presence of Cu2+, however, the adsorbed amount of MX5B increased, presumably mainly due to the formation of complex between azo dye and Cu ion. In addition, the photocatalytic ability of TNT towards MX5B also enhanced when solution contained 2-10 mg/L Cu2+. Addition of humic acid stabilized the nanomaterials in solution, while decreased the adsorption and photodegradation efficiency of pollutants. The zeta potentials and hydrodynamic radii of nanomaterials changed significantly when the solution pH is close to the isoelectric points of nanomaterials. Results obtained in the study showed that the developed 1-D CNT/TNT nanomaterials have high specific surface areas and functional groups on surfaces, which can be adsorption heavy metals as well as organic pollutants under suitable conditions, and the adsorbed pollutants will be removed under illumination of UV-Vis light at a time.

Functionalized 1-dimensional nanomaterials, titanate nanotubes (TNT), carbon nanotubes (CNT), refractory organics, heavy metals, coupled removal