Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/52883
標題: 合成可見光應答奈米光觸媒/電導型奈米觸媒複合材料特性及效能鑑定和去除植物賀爾蒙反應機制探討
Photodegradation of Ethylene Using UV/VIB/DV Voltage Prepared from Nano-Sized TiO/sub 2/ Composite
作者: 林耀東
李元堯
關鍵字: 環保工程;應用研究;nano-sized photo-catalyst composite material;奈米光觸媒複合材料;參雜碳或氮二氧化鈦;動力反應;TiO2/CTN;量子尺寸效應;紫外/可見光;電導催化劑;C-doped;N-doped;C;N-doped TiO2;TiO2/CTN;Quantum size effect;UV/VIB;electricallyconductive catalyst
摘要: 
蔬果採收後會自身產生植物荷爾蒙(plant hormone)-乙烯氣體(C2H4)。少量乙烯氣體能誘發蔬果完熟(ripening)及其他如產生苦味(bitter favors)、減少葉綠素(yellowing of green leafy vegetables)及誘發疾病等不良反應(Abeles et al.,1992),導致降低蔬果綵後儲存期限。傳統蔬果採收後儲存環境乙烯控制方法包括通風(venting)、高錳酸鉀(KMnO4)、觸媒氧化劑(catalytic oxidizers)、氣調儲存(modifiedatmosphere package, MAP)及臭氧(O3)等。上述方法因設備/操作費用高昂不符經濟效益或無法將乙烯濃度降至所需低濃度,故無法有效延長蔬果保鮮期限。因此研發新穎移除空氣中植物荷爾蒙至所需低濃度之技術為當今農產工業克不容緩之關鍵課題。本研究希研發奈米光觸媒複合材料做為蔬果保鮮劑,以有效降低蔬果儲存環境條件下之乙烯氣體濃度。目前二氧化鈦光觸媒去除環境汙染物已被廣泛研究,惟二氧化鈦主要應用之瓶頸為僅可利用UV 光源,無法有效利用自然界免費太陽光源。文獻指出若要提升其二氧化鈦光觸媒功能主要關鍵需從尺寸及材料改質兩方向著手。材料部分本研究將研發能使用可見光之光觸媒材料包括掺雜碳或碳及氮之二氧化鈦。另外利用UV 或可見光源,均無法充分利用表面之活性位址(大於50%表面積無法被光源照射到),因此本研究另將嚐試結合二氧化鈦與奈米碳管之導電型CNT/TiO2 奈米複合材料於外加電壓方式取代光源(無光源條件下)進行催化活性測試,希藉由奈米材料高比表面積特性大幅提升材料有效利用率。同時結合奈米碳管及光觸媒所合成之奈米複合材料,亦可強化吸附及觸媒降解效能,且奈米碳管材料可作為二氧化鈦之支架。至於在尺寸部份,本研究團隊亦將製備不同尺寸(奈米級及微米級)之光觸媒複合材料,以深入探討尺寸效應對光觸媒活性影響機制。至於材料製備方式,本研究初步將選用化學氣相沉積法配製二氧化鈦,其主要原因除符合上述要求外,本研究團隊亦已成功合成相關奈米級材料並掌握如何控制粒徑等關鍵技術。本研究主要工作項目包括將控制合成反應器溫度、氣體組成和濃度及前驅物濃度等因素,以調控及探討奈米微粒合成最適化操作條件及對奈米複合材料基本性質之影響。所製備之複合材料將分析其晶型(crystal lattice)種類、礦物組、粒徑及表面電位、比表面積及孔徑分佈、表面形態(morphology)、結構及表面累積之中間或最終產物所合成之奈米光觸媒複合材料將進行光催化活性效能測試,並將以植物荷爾蒙做為目摽污染物。由於現今光觸媒研究探討均在一般正常環境下測試與蔬果儲存環境大異其趣,因此因應蔬果儲存環境特性,本研究將以自行設計連續/批次式環境反應系統測試上述奈米光觸媒複合材料催化活性效能。實驗環境參數包括:1. O2 濃度、2. N2 濃度、3. C2H4 濃度、4. 溼度、5. 反應器溫度,並分別分別在1. UV、2. 可見光源或3. 無任何光源下外加電壓方式進行探討反應速率、機制及最佳操作條件,實驗數據並將嚐試以反應動力模式如bimolecular form of the Langmuir-Hinshelwood(L-H kinetic model)反應動力模式描述光催化反應動力。最後本計劃將依研究成果模擬及設計光化學反應器之各項參數,並整合及開發奈米複合材料應用於降解植物賀爾蒙之關鍵技術。

This proposed project is to develop innovative materials for the preservation offruits and vegetables after their harvest. It is well known that gaseous ethylene isrelated to the ripening and diseases of fruits and vegetables in post-harvestoperations. During the ripening process, fruits and vegetables are always associatedwith a concomitant sharp increase in ethylene production. As a result, it acceleratesquality loss such as softening, color evolution, aroma development in fruits andvegetables. Furthermore, small increment of ethylene increases the pathogensusceptibility and physiological disorders of fruits and vegetables, which results innet reduction of post-harvest life. Conventional methods for the control of ethyleneinclude the modified atmosphere packaging (MAP, i.e. low-temperature,low-pressure), venting, potassium permanganate oxidation (KMnO4), catalyticoxidizers, and ozone exposure. None of these methods is both cost-effective andsafe; specifically methods such as ozone and permanganate can be health hazards.There is need to develop innovative and cost-effective technique for the control ofethylene as to preserve the post-harvest quality of fruits and vegetables. Success ofthis project will redesign current practices in post-harvest preservation of fruits andvegetables in the agro-industries.The major objective of this research proposal is to synthesize, characterize, andtest nano-sized materials for the degradation of ethylene. Nano-sized materials, dueto their small size, have high specific surface area and chemical reactivity. Thesematerials can be processed following the principle of green manufacturing. Thefollowing nano-sized materials and nano-composites will be studied: 1) nano-sizedTiO2, (2) nano-sized N-doped TiO2 ,(3) nano C-doped TiO2, (4) nano-sizedN,C-doped TiO2, and (5) CNT/TiO2. These nanomaterials will be characterized formorphology (SEM), crystallinity (HRTEM and XRD), specific surface area (N2 BET),porosity (N2, BET), surface functionality (FTIR) and surface molecular structure(XPS). Multi function scanning probe microscope (SPM) will also be employed tounderstand adsorption and surface reaction behavior of single nanomaterial usingscanning thermal microscope (SThM) function and electrostatic forces microscope(EFM) function.The degradation of ethylene will be performed in a batch/continuous flow system.The light source is provided using UVA light, visible light or DC voltage. The UV/VISintensity is selected by adjusting the distance between the lamp and the titania -coated glass-plate. High-purity nitrogen gas pass through a water bubbler to setthe desired water vapor level. An oxygen gas flow is combined with the nitrogen andethylene flows to produce the desired carrier gas mixture. The thermocouples isused to measure the temperature of the inlet and outlet gas streams. Theconcentrations of ethylene, carbon dioxide, carbon monoxide, and ethylene aremeasured using GC/FID. To adjust and maintain the temperature of the reactor, thereactor is immersed into a temperature-controller water bath. TO correlate theethylene rate data, a bimolecular form of the Langmuir-Hinshelwood rate equationwill be used in the research.
URI: http://hdl.handle.net/11455/52883
其他識別: NSC97-2221-E005-096
Appears in Collections:土壤環境科學系

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