電化學氧化法及輝光放電電解法降解水中 
安替比林汙染物

地表水及地下水中常檢測出各種藥物類新興污染物(例如抗炎藥物-安替比林(Antipyrine)，而常規之廢水處理對此類污染物之去除效能不佳，需研發對其有效之去除方法。本研究使用摻硼鑽石電極(Nb/BDD)藉由電化學氧化法及輝光放電電解法降解Antipyrine，並透過改變實驗之各項參數，得出較佳降解條件，並使用電子自旋共振，測試自製摻硼鑽石電極(Nb/BDD)電化學氧化產生自由基之效果，做為後續研究與實際應用之依據。 XPS及Raman之分析結果表明，B原子已成功摻入自製BDD電極之鑽石晶格中，並確認其具有sp3 C-C鍵之鑽石結構，推算出之硼原子濃度約為7.56×1020 cm-3，硼碳比為3%。此外，亦透過SEM、EDX及XRD分析自製BDD電極之表面特性，其晶體平均粒徑大小為289 nm，鑽石微晶尺寸為23 nm，與兩種商用BDD電極(Diachem及NeoCoat)之分析結果類似，但其摻硼量較高且晶體平均粒徑與鑽石微晶尺寸較小。循環伏安法之分析結果顯示，Antipyrine在自製BDD電極上可被氧化，但為電化學不可逆。因此，其可被直接電氧化降解。於0.5 M Na2SO4之電解質中，三種電極之循環伏安法和線性伏安法掃描結果顯示，其析氧電位皆≥2.0 V vs. Ag/AgCl 。電化學氧化法試驗結果顯示，使用Na2SO4比使用NaCl作為電解質時，降解效果較佳。電解60分鐘即可將Antipyrine降解至ND，準一階反應常數k值為1.31×10-3 s-1；TOC之去除率則為96.5%，準一階反應常數k值為3.75×10-4 s-1。而提升電流密度雖可有效增強Antipyrine及其TOC之降解速率，但電流密度由0.5 A/cm2增為1.0 A/cm2時，其去除率並無明顯差異。輝光放電電解法之試驗結果顯示，使用寬0.3 cm之銅片作為陰極並搭配BDD電極作為陽極時的降解效果最佳，電解20分鐘即可將Antipyrine降至ND，準一階反應常數k值為4.38×10-3 s-1，TOC之去除率則為98%，準一階反應常數k值為9.03×10-4 s-1，比能耗為44 Wh/mg-TOC。以自製電極所得電降解Antipyrine之較佳參數(電解質為0.5 M Na2SO4、電流密度為0.5 A/cm2及陰極為Ti板)進行Diachem及NeoCoat電極對100 mg/L Antipyrine降解試驗，發現其皆可於60 min將Antipyrine降至ND，而TOC去除率分別為96%及97%，與自製電極之去除率(97%)類似。此三支電極在醫療廢水中電降解Antipyrine及其TOC 120 min的去除率亦相近。 ESR之分析結果顯示，在四種電解質(Na2SO4、NaCl、HClO4及H2SO4)之水溶液中進行電解，皆能產生DMPO-OH之訊號，而在酸性電解質中有明顯較高訊號強度。推測本研究的電解條件皆可產生•OH，且於酸性電解質中較有利於生成•OH，而有利於Antipyrine之間接電氧化降解。 LC/MS之分析結果顯示，電氧化降解Antipyrine之主要中間產物分別為1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one (m/z 189)、N'-acetyl-N'-methyl-2-oxo-N-phenylacetohydrazide (m/z 221)、N'-acetyl-N'-methyl-2-oxo-N-phenylacetohydrazide hydrate (m/z 237)、N-methyl-N'-phenylacetohydrazide (m/z 165)、aniline (m/z 94)、benzene-1,4-diol(m/z 111)、cyclohexa-2,5-diene-1,4-dione (m/z 109)，蘋果酸(Malic acid)、馬來酸(Maleic acid)及草鞍酸(Oxamic acid)。

關鍵字

電化學氧化法；輝光放電電解法；摻硼鑽石電極(BDD) ；藥物污染；安替比林； Raman ； XPS/ESCA ； ESR

並列摘要

Regarded as emerging contaminants, drug compounds (e.g. anti-inflammatory drug antipyrine) are frequently detected in surface water and groundwater. These pollutants usually cannot be effectively removed by conventional wastewater treatment processes. Therefore, it is necessary to develop techniques for effective removal of drug emerging contaminants. In this study, a lab-made boron-doped diamond electrode (Nb/BDD) was used to degrade antipyrine by electrochemical oxidation and glow discharge electrolysis under different operating conditions. Two commercial BDD electrodes (Diachem and NeoCoat) were also tested for antipyrine degradation for comparison. The results of X-ray photoelectron spectroscopy (XPS) and Raman analyses showed that the BDD film had a structure of diamond (sp3C-C) and boron atoms were successfully located in the diamond crystal lattice ( [B] = 7.56×1020 cm-3, B/C ratio = 3%). In addition, the three BDD electrode exhibited similar surface characteristics of BDD films in SEM, EDX and XRD analyses; however, the concentration of boron element was higher in the lab-made BDD film than in the commercial ones. The cyclic voltammetry analysis using the self-made BDD showed a peak of antipyrine oxidation without corresponding reduction, revealing that its redox behavior was electrochemically irreversible and antipyrine could be degraded by direct electro-oxidation on the BDD. The cyclic and linear voltammetric scans in the electrolyte of 0.5 M Na2SO4 showed that the oxygen evolution potentials of these three electrodes were ≥2.0 V vs. Ag/AgCl. Na2SO4 was better than NaCl to be used as the electrolyte for the electrochemical degradation of antipyrine. After 60-min electrolysis, antipyrine was degraded to ND with a TOC removal rate of ~97%, and their pseudo-first-order reaction constants (k) were 1.31×10-3 and 3.75×10-4 s-1, respectively. Although increasing the current density effectively enhanced the degradation rate of antipyrine and TOC, a slight increase in removal rate was observed when the current density increased from 0.5 to 1.0 A/cm2. The results of antipyrine degradation using the glow discharge electrolysis showed that the best performance was achieved using the lab-made BDD anode and a copper sheet cathode. Antipyrine was degraded to ND within 20 minutes of electrolysis with k = 4.38×10-3 s-1, while the removal rate of TOC was ~98%, (k = 9.03×10-4 s-1), with the specific energy consumption of 44 Wh/mg-TOC. The better operating parameters obtained from the antipyrine degradation using the lab-made anode were also used to degrade antipyrine using the two commercial electrodes. The results showed that both Diachem and NeoCoat electrodes could degrade 100 mg/L antipyrine to ND for 60-min electrolysis (at 0.5 A/cm2 in 0.5 M Na2SO4), with TOC removal rates of ~96% and ~97%, respectively, which were similar to that of the lab-made BDD (~97%). The three electrodes also exhibited similar antipyrine or TOC removal rates for 120-min electrolysis in hospital wastewater. According to the DMPO-OH signals of electron spin resonance (ESR) analysis, all the tested BDD electrodes could generated •OH in four electrolytes (Na2SO4, NaCl, HClO4 and H2SO4), and the peak intensities of DMPO-OH signals were greater in the more acidic electrolytes, indicating that the acidic electrolytes were more favorable for the electrochemical generation of •OH, favorable for the electrochemical degradation of antipyrine. The major intermediates of Antipyrine electrochemical degradation were 1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one (m/z 189), N'-acetyl-N'-methyl-2-oxo-N-phenylacetohydrazide (m/z 221), N'-acetyl-N'-methyl-2-oxo-N-phenylacetohydrazide hydrate (m/z 237), N-methyl-N'-phenylacetohydrazide (m/z 165), aniline (m/z 94), benzene-1,4-diol(m/z 111),cyclohexa-2,5-diene-1,4-dione (m/z 109), malic acid, maleic acid, and oxamic acid.

並列關鍵字

Electrochemical oxidation ； Contact glow discharge electrolysis (CGDE) ； Boron-doped diamond film (BDD) ； Drug emerging contaminants ； Antipyrine, X-ray Photoemission Spectroscopy (XPS/ESCA) ； Raman Spectrometer ； Electron spin resonance (ESR)

參考文獻

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