類別:

黃銅水錶於自來水中腐蝕之機制與鉛、銅、鋅釋出之評估

2022-01-01T00:00:00Z

標題: 黃銅水錶於自來水中腐蝕之機制與鉛、銅、鋅釋出之評估; Corrosion and release of lead, copper and zinc from brass water meter in drinking water 作者: Ching-Hsuan Hsu; 徐靖軒摘要: 腐蝕對於住戶管線系統有很大的影響，可能會造成管線滲漏、管線堵塞以及管件微量物質的釋出。此研究的目的是要了解黃銅水錶在不同的自來水水質條件下腐蝕的情形。本研究藉由感應耦合電漿質譜儀(ICP-MS)偵測鉛、銅、鋅的釋出，並結合表面分析以及電化學方法來觀察黃銅水錶在自來水中腐蝕及腐蝕產物生成的情形。結果顯示因局部電化腐蝕，大量的鉛及鋅會自黃銅水錶釋出。在實驗初期(0-5天)，根據能量色散X射線光譜分析(EDS)，黃銅水錶表面的鉛及鋅的百分比含量有明顯的下降，伴隨著腐蝕電流密度的上升以及表層電阻阻抗的下降，這些結果能夠說明實驗初期有劇烈的腐蝕現象發生；在實驗後期(>10天)，根據金屬釋出及EDS結果進行分析，可以發現含銅及鉛的腐蝕產物在黃銅表面生成，而抑制了腐蝕反應，電化學的檢測亦證實此項結果。當自來水pH值降低，會促進鉛、銅、鋅的釋出，相反的pH值的上升能抑制金屬自黃銅水錶釋出。自由餘氯能夠稍微減少鉛的釋出，然而自由餘氯會大大提升銅及鋅的釋出。; Corrosion has adverse impacts on household plumbing systems, which may lead to water leak, pipe clogging and metal release. In this study, corrosion of brass water meter was investigated using batch experiments with various tap water conditions. The release of lead, copper and zinc was monitored using inductively coupled plasma mass spectrometry (ICP-MS) and electrochemical tests. Scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) was used to investigate the change of surface morphology and elemental composition of the corrosion processes. The results showed that high levels of lead and zinc were released from brass water meter due to localized galvanic corrosion among lead, copper and zinc. During the early stage of corrosion (0-5 d), the weight percentage of lead and zinc on the brass water meter surfaces decreased substantially as evidenced by the EDS results. The corrosion current density (Icorr) increased and film resistance (RF) decreased during that period. These results illustrated that severe corrosion occurred. During the later stage (> 10 d), according to the ICP-MS and EDS results, copper and lead corrosion products formed on the brass water meter surfaces, which retarded the corrosion process. The release of lead, copper and zinc was enhanced by a lower pH. Free chlorine was found to slightly reduce the release of lead while promote the release of copper and zinc.

麻瘋樹籽油渣之焙燒

2012-01-01T00:00:00Z

標題: 麻瘋樹籽油渣之焙燒; Production of Bio-char from Jatropha-seed Cake via Torrefaction 作者: Tsung-Chi Hsu; 許聰吉摘要: 本研究利用焙燒程序處理麻瘋樹種籽搾油後油渣，以提升其燃料性能。生質廢棄物有水分含量高、熱值低以及運輸貯存上的問題，若透過熱處理程序，雖然有部份質量損失，但仍能保存大部份熱能，可達到熱值提升，以及能量密度增加，並且焙燒產物具疏水性之效果。本研究先進行熱重分析(thermagravimetric analysis, TGA)，決定油渣與脫脂油渣較合適之焙燒溫度(Tr)，與決定焙燒時間(tr)。依TGA結果擇定以260、280、300 °C及時間10-60 min進行焙燒，觀察兩種樣本於各操作條件下之焙燒反應情形。實驗結果顯示油渣在260、280、300 °C能量密度提升之最高值分別為1.25、1.29、1.30，脫脂油渣則分別為1.28、1.37、1.39，兩者焙燒產物之平均乾基熱值(high heating value in dry basis, HHMD)在5,000-6,000 kcal kg-1。焙燒產物固定碳比例上升，顯示更具燃煤特性。結果經迴歸分析後可歸納出熱值與固定碳之間呈現高度相關性質。與台電燃煤採購標準(STP)作為比較，油渣及脫脂油渣之焙燒產物之含硫量、灰分含量均在STP標準D之規範值以內。本研究綜合各項產物特性分析以作為最適操作條件之評估，結果顯示Tr = 280 °C，tr = 40 min之焙燒產物濕基高位熱值(high heating value in wet basis, HHMW)為5,700 kcal kg-1，符合STP標準D (HHMW ≧ 5000 kcal kg-1)之規範。; Torrefaction is a thermal treatment used to enhance the properties of fuels. In this study, Jatropha curcas L. seed cake after mechanically expelling ectraction of oil (denoted as Jatropha pressed cake or JPC) and the de-oiled JPC after further solvent extraction of residual oil using n-hexane (symboled as JDPC), were examined for their torrefaction performances. The thermogravimetric analysis (TGA) were employed to elucidate the thermal decomposition behaviors of JPC and JDPC. Temperatures with acceptable mass loss of 5-10% of JPC in TGA were in the range of 260-310 °C, suggesting the further tests of the torrefaction at 260, 280 and 300 °C. The torrefaction temperature (Tr) and time (tr) play important roles on the production yield of bio-char. The tr employed were 10 to 60 min. During the torrefaction at a setting temperature Tr, the biomass further lost its mass. The characteristics of torrefied products were measured and assessed. Proper torrefaction conditions were elucidated, considering the balance of enhancing the energy density (ED) while retaining the yield (Ym). The results indicate that at Tr= 260, 280 and 300 °C, ED values of torrefaction products of JPC are 1.25, 1.29 and 1.30, while those of JDPC are 1.28 1.37 and 1.39, respectively. The high heating values per mass in dry basis (HHMD) for the cases using JPC and JDPC are about 5,000-6000 kcal kg-1. The fixed carbon content (MFC) increases after torrefaction, enhancing its coal-alike property. The MFC is highly and positively correlated with HHMD. Employing the appropriate conditions of Tr = 280 °C and tr = 40min, the torrefied products containing negligible sulfur, ash of 9.27 wt.% and HHMW of 5700 kcal kg-1 meet the D quality of coal standards of Taiwan Power Co. with sulfur < 1.1 wt.%, ash < 16 wt.% and HHMW >5000 kcal kg-1.

鹼性條件下臭氧去除水中全氟辛酸

2010-01-01T00:00:00Z

標題: 鹼性條件下臭氧去除水中全氟辛酸; Perfluorooctanoic acid ozonation in alkaline condition 作者: Cheng-Yi Chang; 張丞毅摘要: 全氟碳化物(perfluorinated compounds，PFCs)常被半導體與光電產業用來酸洗電子零件或晶圓表面，或當作光版程序的界面活性劑。PFCs因其強大的碳-氟鍵結(C-F bond)，在自然界中不易被光解、水解或生物降解，也導致其在環境中有持久性與生物累積性的特質。許多文獻已證實PFCs具有致突變腫瘤與致癌性，因此利用工程方法去除PFCs為近年來熱門的研究議題。其中，全氟辛酸(perfluorooctanoic acid，PFOA)為一種最被廣泛應用的人造全氟碳化物，且比起許多其他的PFCs更具毒性、更難以分解。 PFOA無法在中性或酸性環境下使用臭氧直接降解，因此本研究嘗試使用臭氧在鹼性條件下，產生氫氧自由基(hydroxyl radical，OH•)降解水中PFOA。實驗中改變之參數有：pH (5~6, 11)、臭氧濃度(0 wt%, 2 wt%, 2.5 wt%, 7 wt%, 9.5 wt%, 10.5 wt% (ozone/oxygen))，PFOA初始濃度(50 ppb, 5 ppm)、過氧化氫(H2O2/O3 =5, 10, 20 molar%)、腐植酸(15 mg/L)與外加超音波場源震盪影響。當在鹼性條件(pH=11)下，使用臭氧能有效降解PFOA。使用2.5 wt%之臭氧可得到最佳處理效率(90 %)；若添加過氧化氫增加氫氧自由基之穩定態濃度，可使去除效率增加15 %~ 56 %；添加腐植酸抑制氫氧自由基之穩定態濃度，會使去除效率減少15 %~44%；外加超音波場源震盪則增加2 %去除效率，顯示降解機制為氫氧自由基攻擊目標污染物。此方法可將PFOA降解成毒性較低的中間產物如：全氟庚酸(PFHpA)、全氟己酸(PFHxA)、全氟戊酸(PFPeA)、全氟丁酸(PFBA)與氟離子，以減少PFOA在環境中的危害。此外，本研究亦嘗試將最佳操作條件用於處理全氟辛烷磺酸(Perfluorooctanesulfonic acid, PFOS)與實廠廢水，結果顯示PFOS去除效率可達84 %，用於處理實廠廢水6小時可去除92 %之PFOA、4小時即可去除99 %之PFOS。; Perfluorinated compounds (PFCs) have been widely used as surfactants in photolithographic processes in semiconducting and optoelectronic industry. The highly stabilities in photodegradation, hydrolysis, and biodegradation of perfluorinated compounds is attributed to their strong C-F bond, resulting in persistence and bioaccumulation in the environment. PFCs have been proved to be a carcinogen to human. Perfluorooctanoic acid (PFOA), one of human-made PFCs, is more toxic and difficult to be degraded than many other PFCs. PFOA can not be degraded by direct ozone reaction in acidic/neutral condition. Consequently, this study aimes to investigate PFOA ozonation in alkaline condition due to the generation of hydroxyl radical to degrade PFOA. The degradation efficiency of PFOA varied with pH values (5~6, 11), ozone concentrations (0 wt%, 2 wt%, 2.5 wt%, 7 wt%, 9.5 wt%, 10.5 wt% (ozone/oxygen)), the initial PFOA concentrations (50 ppb, 5 ppm), the molar ratio of hydrogen dioxide to ozone (H2O2/O3 =5, 10, 20 molar%), presence of humic acid (15 mg/L) and with the assistant of ultrasound. In alkaline condition (initial pH=11), ozonation can effectively degrade PFOA and exhibits the best efficiency with 2.5 wt% (ozone/oxygen). Adding hydrogen dioxide to enhance the steady concentration of hydroxyl radical (OH•) increases 15~56% of the conversion. Adding humic acid to restrain the steady concentration of OH• decreases 15~44% of the conversion. Combining ultrasonic vibration increases 2% of the conversion. Those phenomena illustrate that the hydroxyl radical attacking the target compound is the main mechanism of degradation. In this study, PFOA can be degraded to the-lower-toxic intermediates such as PFHpA, PFHxA, PFPeA, PFBA, and fluoride ion. In addition, this technology was also applied in treating perfluorooctanesulfonic acid (PFOS) and industrial wastewater under the optimum operating condition. Result shows that 84% PFOS can be degraded, and 92% PFOA and 99% PFOS in the industrial wastewater can be degraded within 6 hours and 4 hours, respectively.

高纖維飲食大鼠盲腸中纖維素分解菌之培養

2016-01-01T00:00:00Z

標題: 高纖維飲食大鼠盲腸中纖維素分解菌之培養; Enrichment of cellulose-saccharifying bacteria communities from rat fed with high-fiber diet 作者: Chi-Chen Chen; 陳紀臻摘要: 近年來，纖維素被認為有潛力成為穩定的生質能源來源。科學家先利用酸或酵素水解纖維素成還原糖類，微生物再利用還原糖產生生質能源，如乙醇與氫氣。與酸水解纖維素相比，酵素水解雖效率較差，但所需要的環境較為溫和，運作成本也較低。為了增加生質能源產量，科學家積極尋找能高效率分解纖維素產糖的微生物。此篇論文的目的為從高纖維飼料餵養之大鼠盲腸中尋找高效率產糖的纖維素分解菌。大鼠盲腸內的微生物被優化培養在含有水溶性纖維素的培養基中，並以剛果紅染色法選擇能代謝水溶性纖維素的菌落，將其養成菌液後以二硝基水楊酸試劑測定菌落的產糖能力。其中單一菌落RCF (rat cecum colony F)的水溶性纖維素產糖能力最佳。全基因定序(whole-genome sequencing)的結果顯示此單一菌落內共含有九種菌株，主要為四株梭狀芽胞桿菌、大腸桿菌、瘤胃脫硫腸狀菌及產氣腸桿菌。且根據前人的研究，梭狀芽胞桿菌被推測為此菌落內主要的纖維素產糖者，而大腸桿菌、瘤胃脫硫腸狀菌及產氣腸桿菌則被視為只有耗糖的能力。同時，我們發現RCF分解晶體纖維素產糖的能力不佳。因此，為了增加RCF的晶體纖維素產糖效率，本研究針對RCF中的菌種特性採用了抗生素處理法、酒精處理法及高溫處理法，期待能增加菌液中梭狀芽胞桿菌的比例。革蘭氏陰性菌抗生素(萘啶酸)被用來抑制大腸桿菌、瘤胃脫硫腸狀菌及產氣腸桿菌等耗糖菌，而乙醇及高溫則被用來去除菌液中的非產孢子菌(梭狀芽胞桿菌及瘤胃脫硫腸狀菌之外的所有菌種)的比例，提高族群的纖維素產糖量。結果顯示抗生素能夠有效增加RCF的固態纖維素產糖能力。然而，次世代定序與定量即時聚合酶鏈鎖反應(real-time PCR)的結果卻顯示此抗生素減少了梭狀芽胞桿菌在菌液中的數量及比例，推翻了我們預計產糖量會與梭狀芽胞桿菌比例同時增加的假設。因此我們推測有三個可能：1. 萘啶酸改變了菌液中梭狀芽胞桿菌族群的組成比例，增加高產糖的菌株的比例，減少了高耗糖的菌株。2. RCF內有其他能分解纖維素產糖的菌種，而抗生素抑制了梭狀芽胞桿菌，減少了纖維素的競爭，使得其他纖維素分解菌增加。3. 原本預計未有纖維素產糖能力的大腸桿菌其實能夠分解纖維素，因此產糖量與大腸桿菌的比例同時增加。; Cellulose is one of the highly abundant organic compounds on earth, which may be one of the alternative energy resources. Cellulose can be chemically or biologically degraded into simple sugars, which can be used to generate bioenergy such as ethanol and hydrogen. Chemical hydrolysis of cellulose requires high energy input. Therefore, bio-degradation may be a feasible process. The objective of the study is to isolate and identify cellulose-saccharifying microorganisms from rat cecum fed with high-fiber diets. A Sprague Dawley (SD) rat was fed with high fiber diets for 6 months. Mandel-Reese (MR) media with sodium carboxymethyl cellulose (CMC) as the sole carbon source, was used to enrich cellulolytic microbes. Congo red overlay method was used to select the cellulose-degrading colonies on the isolation plates. The congo red-positive colonies were inoculated into MR media with CMC, and the reducing sugar were measured by 3,5-dinitrosalicylic acid (DNS) colorimetric method. Enrichment culture RCF (rat cecum colony F), the one with highest CMC-saccharifying rate, was selected for crystalline cellulose-saccharifying tests and further studies. The whole-genome sequencing result from the 30-day-incubation RCF culture showed a community of bacteria consisted with four Clostridium spp., Desulfotomaculum ruminis (D. ruminis), Escherichia coli (E. coli), Enterobacter aerogenes, Pseudoflavonifractor capillosus (P. capillosus) and Cellulomonas cellasea. In addition, time-coursed reducing sugar concentrations from α-cellulose indicated that microbial community RCF consumed more reducing sugars than it produced within 8 days of incubation. According to previous studies, Clostridium spp. were most likely to be cellulolytic and D. ruminis, E. coli and Enterobacter aerogenes were speculated to be non-cellulolytic in this microbial community. In order to enhance the sugar yields from crystalline cellulose, α-cellulose, three treatments based on the characteristics of community were conducted: antibiotic, heat and alcohol treatments. Nalidixic acid, an antibiotic against gram-negative bacteria, was used to inhibit D. ruminis, E. coli and Enterobacter aerogenes. Heat and alcohol were applied to favor spore formers, Clostridium spp. and D. ruminis. Species- distribution with time was analyzed using real-time PCR and 16S ribosome RNA gene amplicon sequencing. Amongst these three treatments, antibiotic enhanced the sugar yield successfully. However, real-time PCR and 16S rRNA gene amplicon sequencing results showed that both the microbial populations and fractions of Clostridum spp. were reduced substantially by antibiotic treatment. Three possible reasons for the sugar yield enhancement after antibiotic treatment were: 1. Antibiotic changed the Clostridium population structure into more cellulose-saccharifying community. 2. Antibiotic treatment provided the competitive advantage of minor microorganism having high cellulose-saccharifying ability. 3. The predicted non-cellulolytic E. coli could perform cellulosic saccharification.