結合光觸媒與化學濾網之協同作用去除室內揮發性有機污染物

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Title:	結合光觸媒與化學濾網之協同作用去除室內揮發性有機污染物
Other Titles:	Synergistic Effect of Chemical Filters with Photocatalysts for the Removal of Indoor Volatile Organic Compounds
Authors:	張蕙嵐 Chan, Hui-Lan
Contributors:	鄧宗禹 Den, Walter 東海大學環境科學與工程學系
Keywords:	二氧化鈦、化學濾網、懸浮分子污染物、異丙醇、甲苯 photocatalysts, chemical filter,airborne molecular contamination,isopropanol, toluene
Date:	2010
Issue Date:	2011-01-24T07:25:35Z (UTC)
Abstract:	本研究之旨在發展結合二氧化鈦光觸媒與活性碳吸附式化學濾網之新式化學濾網，使用光觸媒有效的分解氣相污染物在經由活性碳濾網有效吸附污染物，達到室內品空氣品質及無塵室中空氣品質標準並延長化學濾網之使用壽命。新式化學濾網應用於控制室內品空氣品質及無塵室中之懸浮分子污染物(Airborne Molecular Contaminants, AMCs)，研究中目標污染物以氣相異丙醇(Isopropanol)為測試對象，測試新式化學濾網對異丙醇的效率評估及不同光催化參數的影響及結合二氧化鈦光觸媒與活性碳化學濾網的協同作用，並與先前研究之甲苯做合併之探討。本研究係將二氧化鈦披覆於不織布上，再與化學濾網壓併而成置於反應器中並以連續流反應方式測試之。研究結果顯示改變異丙醇不同進流濃度下，已披覆光觸媒不織布光催化效率隨濃度增加而降低；在不同相對濕度參數下，以相對濕度30 % 對已披覆光觸媒不織布光催化效率最佳。以改變不同二氧化鈦披覆量，披覆量為4.0mg/cm2與披覆量1.8 mg/cm2光催化效率沒有明顯增加很多。在改變不同光強度參數下，18W紫外燈管比13W紫外燈光催化效率佳。異丙醇之光催化過程的中間產物丙酮的變化，當反應物的濃度增加時，丙酮的生成量較多，異丙醇和丙酮會產生競爭吸附的現象，但因紫外光的光強度較不足，以至於不能完全將丙酮完全分解。比較單一化學濾網與結合披覆二氧化鈦不織布與活性碳化學濾網，若以使用10% 吸附破出濾網就必須更換，由實驗結果顯示以異丙醇為污染物，顯示異丙醇平均進流濃度約為48 ~53 ppmv，光觸媒不織布搭配化學濾網可使用(~9 小時) > 先由光觸媒不織布光催化後在流經化學濾網(~4.5小時) > 單一活性碳化學濾網(~1.5小時)。當異丙醇平均進流濃度約為9 ~10 ppmv , 光觸媒不織布搭配化學濾網可使用(~30小時) 比單一活性碳化學濾網(~10小時)可延長使用壽命。評估結合已披覆TiO2不織布搭配化學濾網於不同甲苯進流濃度之使用情形，假設破出10%就需更換，甲苯進流濃度7 ppmv(~40小時)，後貫穿時間約為170個小時；40 ppmv(~8小時)，最後貫穿時間約為35個小時，推測最後濾網會貫穿之原因，甲苯在光催化過程的中間產物會使觸媒產生毒化的現象，導致最後會使濾網貫穿。由實驗結果顯示不管在高濃度或是低濃度範圍，光觸媒之不織布搭配化學濾網的形式確實可有效延長使用壽命，主要是同時利用濾網的吸附能力與光觸媒的分解能力使濾網之使用壽命大幅延長，將可大幅減低更換濾網的使用成本，對於提高晶圓產品的良率，為一具有商業價值開發的技術。 The study of TiO2-coated non-woven cloth combined with adsorptive chemical filters, gaseous pollutant with effect to decompose by photocatalytic and could be further adsorption contaminants by activated carbon filter, indoor air and clearnrooms air quality to achieve standard then lengthen the service life of chemical filters. The application in controlling the indoor air quality and airborne molecular contaminants (AMCs) by chemical filter, this research target contaminant of gaseous isopropanol, investigated used synergistic effect of chemical filters with photocatalysts to efficiency evaluate and several operating variables for isopropanol, and previously research to combination discuss for toluene. <br> In this study, for the continuous-flow a sheet of non-woven cloth were coated with TiO2 powders and pressed against a sheet of chemical filter. The result express photodegradation efficiency of isopropanol significantly reduced with increases in the influent toluene concentration; At the 30% relative humidity gave greater degradation efficiency in the different relative humidity; For the 1.8 mg/cm2 with 4.0mg/cm2 TiO2 loading on non-woven filter on the photocatalytic degradation efficiency of no apparent increase; Effect of UV light intensity on the greater isopropanol degradation efficiency using 18W lamp than that of the 13W lamp; Intermediate products of isoproanol photocatalysis increased concentration acetone increased, compete adsorptive between isopropanol and acetone but UV lamp light intensity to no enough so no complete decompose that acetone.<br>Comparison single chemical filter and combine TiO2 coated non-moven filter with chemical filter, the experiment residues to indicate isopropanol average influent concentration of 48 ~53 ppmv by setting 10 % breakthrough as the base criterion for the comparison of different types filter, it was found that the TiO2 coated non-woven + chemical filter had a duration (~9 hr) > first to pass through TiO2 coated non-woven and then to pass through chemical filter (~4.5 hr) > and the chemical filter along (~1.5 hr); Comparison by setting 10 % breakthrough as the base criterion for the comparison of different types filter, it was found that the TiO2 coated non-woven + chemical filter had a duration (~30 hr) > and the chemical filter along (~10 hr), under isopropanol average influent concentration ot 9 ~10 ppmv. By setting 10% breakthrough as the base criterion for the comparison of different types of photocatalyst chemical filter, it was found that the TiO2-coated non-woven + chemical filter had a duration (~40 hr) final breakthrough time (~170 hr) and (8 hr) final breakthrough time (~35 hr) under toluene influent concentration of 7 ppmv and 40 ppmv, Intermediate products of toluene photocatalysis could be the culprit of poisoning for chemical filter. In this study result demonstrate that chemical filter combined with a TiO2-loaded filter proved to significantly extent the breakthrough times of both toluene and isoproanl contaminated gases, as compared to that of the chemical filter only. This result implies that the life of a chemical filter could be extended by photocatalysis and adsorptive, and its decrease replace cost and bears great potentials in commercial values.
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