EPA-96-04-00-3

096

3,500 千元

2007/11/19

2008/09/18

吳俊哲

永續發展室(停用)

林燕柔

凱特利斯股份有限公司

大氣空氣

甲醛,臭氧,觸媒

Formaldehyde,Ozone,Catalyst

張立德,林樹榮

林樹榮

03-4700347

shulin_aop@hotmail.com

由於室內空氣污染物對人體健康造成之影響已受到相當程度的重視，本計畫主要針對室內空氣污染物之甲醛及甲苯進行臭氧觸媒氧化之研究，並發展乙套可供室內循環淨化處理之實體設備。 本計畫之執行主要分為兩個主要單元，第一階段為實驗室的甲醛及甲苯基本分析工作與臭氧觸媒程序之操作條件測試，以獲得最佳化處理之參數，並據以建立實際設備可應用之技術相關資料。實驗結果顯示：臭氧具單獨氧化甲醛及甲苯的能力，在固定氣體進流量 1500 ml/min，臭氧反應停留時間 48 sec，甲醛及甲苯濃度為 5±0.2 ppm的條件下，每莫耳臭氧可去除0.25莫耳甲醛、0.06莫耳甲苯，接著調整臭氧不同停留時間為96 sec及144 sec，本研究發現臭氧停留時間延長對於甲醛THC去除率效果無明顯增加。然而，卻能提升甲苯及其THC的去除率，主要原因由於甲苯中間產物複雜且型態眾多，臭氧停留時間的增加相對提升臭氧分子與其中間產物能有更充分反應時間。針對觸媒測試方面，顆粒觸媒及觸媒濾網對於甲醛及甲苯吸附能力有限，而且觸媒分解臭氧能力主要由觸媒填充量而定。接著經由不同操作條件的測試，本研究發現甲醛最佳操作參數為濃度5±0.2 ppm之處理程序『雙面觸媒濾網(35g) /臭氧劑量60±1 ppm /相對溼度72%』，可100%去除甲醛及其THC去除率為76%且無殘餘之臭氧濃度。相對甲苯而言，當甲苯濃度5±0.2 ppm最佳處理程序為『雙面觸媒濾網(35g) /臭氧劑量120±1 ppm /相對溼度72%』，甲苯去除率為56%而且其THC去除率為44%，殘餘臭氧濃度19 ppm。整體而言，臭氧可用來氧化甲醛及甲苯兩種氣體，且藉由添加觸媒及溼度的改變以催化臭氧，進而分解成氧化能力強之氫氧自由基加以氧化難以去除的甲醛及甲苯之THC。 本研究第二階段為實場空氣處理設備測試，本團隊至台中XX醫院進行勘查。經過實際調查：此醫院病理科之檢切室中有保存檢體的甲醛(福馬林)以及使用甲苯、二甲苯等有機溶劑，且背景濃度中的甲醛高達1.6 ppm及TVOC都在2.5 ppm之上，因此檢切室為本團隊處理對象。首先，在單獨使用空氣處理設備的風車及觸媒，發現不同換氣率對於甲醛及其TVOC的濃度無明顯去除效果。但是由於本研究的空氣處理設備有加裝HEPA，對於檢切室室內空氣微粒PM2.5及PM10可去除30%以上。接續增加臭氧程序並調整不同空氣設備操作參數，本研究經由不斷測試，最終發現處理檢切室室內空氣的最佳操作參數為『換氣率16 ach /觸媒量200 g /臭氧進流濃度2.5 ppm』，經過六小時長時間處理可去除檢切室中甲醛濃度降為0 ppm，而且對於TVOC濃度可處理至0.7 ppm，皆能符合環保署室內空氣品質建議值(甲醛0.1 ppm，TVOC 3 ppm)，其殘餘臭氧濃度為0.08 ppm可符合OSHA(美國職業安全衛生署)勞工在作業場所8小時所暴露的平均臭氧濃度不可高於0.10 ppm的規定。 本研究依據實場測試結果評估健康風險之危害：報告中指出經由空氣設備系統處理後之甲醛濃度降為0 ppm，因此能降低此氣體對人體帶來的致癌風險，對於殘餘的臭氧濃度經由觸媒催化分解後對人體的急性健康風險指數是屬於偏低的，針對每年操作成本(NT/year)包括電力及耗材成本的估算約為$7,633元。就整體而言：本團隊所研發之空氣設備處理系統與市售空氣清淨機的差異性，主要在於揮發性有機氣體去除率88.7%及CADR值2.048 m3/min皆優於目前市售產品，而且此設備之最大處理風量及處理對象(甲醛及TVOC) 明顯不同於一般市售之空氣清淨機，對於環保署可提供處理室內空氣污染物(甲醛及TVOC)另一新技術，加強有效改善室內空氣品質，方能維護人體健康。

甲醛,臭氧,觸媒

可公開.pdf

0MB

[期末報告]公開版

2009/3/1 上午 12:00:00

Due to the pollution of indoor air affecting on human being’s health has be increasingly noted. This research was conducted using the combination of ozone and goethite catalyst which oxidize indoor air contaminants, such as formaldehyde and toluene. In addition, it is our main target to develop a commercialized equipment of air purification system to deal with polluted indoor air quality. This research is divided into two phases. The first phase is to establish the analytical techniques for better quantifying formaldehyde and toluene concentrations, then use ozone plus goethite catalyst process to develop the best operation conditions as obtained in our lab work. The second phase is to build a pilot- scale equipment employed to determine the useful information for future scaling up. According to the experimental results, it was indicated that 0.25 mole of formaldehyde and 0.06 mole of toluene could be completely consumed by one mole of ozone under the flow rate at 1500 ml/min and ozone retention time at 48 sec. After increasing retention time up to 96 and 144 sec, we found that THC decomposition from the degradation of formaldehyde was not obvious. However, THC removal from the degradation of toluene is rather significant, which indicates the oxidized byproducts from toluene can be effectively attacked by ozone molecules if retention time can be prolonged. Adsorption test was performed by passing those air contaminants through the catalysts bed. It was found that the adsorptive effect of formaldehyde and toluene onto the catalyst was rather minor. The combination of ozone and goethite catalyst can decompose 100% of formaldehyde and 76% of its THC by operating 60 ppm of ozone and 35 g of goethite catalyst at the initial formaldehyde concentration 5±0.2 ppm and relative humidity 72%. Similarly, the removal of toluene was 56% and its THC was 44%. Nevertheless, 19 ppm of ozone was still detected in the offgas. Based on this result, it is very crucial on the further design of pilot-scale system by increasing enough amounts of catalysts to substantially destroy the residual ozone to prevent any potential risk to indoor environment. Since several volatile chemicals, including formaldehyde, alcohols, and xylene, have been widely used in hospital, the pilot test was chosen to treat the indoor air in the selected medical center in Taichung city. According to our preliminary sampling and analysis, the concentrations of formaldehyde and TVOC were found to be 1.6 and 2.5 ppm, respectively. Without using ozone and goethite catalysts, adjusting different average changes per hour (ach) as operated in the air purification system has no effect on the removal of formaldehyde and TVOC in the hospital. However, it can only remove PM2.5 and PM10 up to 30% due to HEPA filtration. When the treatment system was performed at the following condition as 16 ach/ FeOOH 200g/ O3 2.5 ppm for six hours, formaldehyde has been totally removed and TVOC concentration dropped down to 0.7 ppm, which has complied with the suggestion values regulated by EPA Indoor Air Quality (0.1 ppm of formaldehyde, 3 ppm of TVOC). In the mean time, the residual ozone concentration was detected as 0.08 ppm that also conform the regulations by OSHA. In our pilot-scale results the health risk has been significantly decreased according to the calculation of residual target indoor pollutants. In addition, the annual expense including electricity and accessory would cost NT$7,633. If comparing with the other air purification systems as used in the market, the efficiency of treating polluted indoor air should be superior with 88.7% TVOC removal and 2.048 m3/min CADR. Therefore, this new-developed purification facility would have the chance to be commercially applied in the future and the improvement of indoor air quality for some specific building could be expected.

Formaldehyde,Ozone,Catalyst