本文關(guān)鍵詞：氣體擴散陰極法降解水中苯酚和2,4-二氯苯酚的研究　出處：《哈爾濱工業(yè)大學》2015年碩士論文　論文類型：學位論文

  更多相關(guān)文章： 氣體擴散陰極 降解 過氧化氫 中間產(chǎn)物 循環(huán)伏安法

【摘要】：近些年來,在電化學技術(shù)領(lǐng)域,環(huán)境研究者進行了廣泛地研究。目前,一種新型的三相電極—氣體擴散陰極,在陰極原位產(chǎn)生H2O2等強氧化性中間產(chǎn)物催化去除有機物和陰極電催化還原脫鹵方面正備受關(guān)注。本論文研究制備了一種高效的氣體擴散電極,該電極由防水透氣層(氣相層)、金屬導電網(wǎng)(固相層)、催化層(液相層)組合而成,并直接以空氣作為氧源,通過對苯酚、2,4-二氯苯酚的降解,建立了氣體擴散陰極催化處理工藝體系,研究了改變電極運行條件對有機物降解的影響,并結(jié)合表征和電化學方法分析了氣體擴散陰極法對苯酚、2,4-二氯苯酚的降解機理�？疾炝藲怏w擴散陰極對苯酚降解的影響,并進行了表觀動力學分析和鈦網(wǎng)重復性能測試。結(jié)果表明,氣體擴散陰極法降解苯酚的最佳條件:電流密度80 m A/cm2,電解質(zhì)濃度0.2 mol/L,固定p H值4,通氣量40 m L/min。電解40 min,50 mg/L的苯酚即可達到完全降解,電解2 h,COD的去除率可達91%,顯示出良好的電化學催化活性,苯酚降解符合一級反應(yīng)動力學。采用高溫(600℃)煅燒重制電極,結(jié)果表明,新電極1 h對苯酚降解的去除率下降幅度不超過2%,顯示出鈦網(wǎng)良好的重復性能。研究了氣體擴散陰極法對2,4-二氯苯酚的降解,并進行了脫鹵和中間產(chǎn)物分析。實驗結(jié)果表明,在電極間距3 cm,電流密度80 m A/cm2,電解質(zhì)濃度0.2 mol/L,固定p H值4,通氣量60 m L/min時,濃度50 mg/L的氯酚,電解1 h即可完全去除,電解2 h后COD去除率達到80%。根據(jù)脫氯結(jié)果顯示,1 h后脫氯已經(jīng)完成,陰極體系內(nèi)氯離子濃度達到0.41 mmol/L。通過GC-MS對2,4-二氯酚降解進行中間產(chǎn)物檢測,發(fā)現(xiàn)了2-氯酚、4-氯酚、苯酚、對二苯酚、苯醌、順丁烯二酸等物質(zhì)的生成。對氣體擴散電極進行了表征分析,認為電極表面形貌及內(nèi)部孔徑分布不同,造成電極催化活性和選擇性的差異,也是引起苯酚降解差異的主要原因,在炭黑/聚四氟乙烯(PTFE)為3、熱壓壓力10 MPa下成型的電極表現(xiàn)出良好的性能。通過循環(huán)伏安曲線分析,推測苯酚主要在電極形成過氧化氫以及羥基自由基的間接氧化作用下被降解;2,4-二氯苯酚的去除先在電極還原脫氯的作用下,形成一氯酚和苯酚,繼而通過間接氧化作用被降解。
[Abstract]:In recent years, environmental researchers have carried out extensive research in the field of electrochemical technology. At present, a new three-phase electrode-gas diffusion cathode. Catalytic removal of organic compounds and electrocatalytic reduction of halogenation by in-situ production of H _ 2O _ 2 and other strongly oxidized intermediates at the cathode have attracted much attention. A highly efficient gas diffusion electrode has been prepared in this paper. The electrode is composed of waterproof and permeable layer (gas phase layer, metal conducting network (solid phase layer), catalytic layer (liquid phase layer)), and directly uses air as oxygen source through degradation of phenol 2 + 4-dichlorophenol. The process system of gas diffusion cathodic catalytic treatment was established, and the effect of changing electrode operating conditions on the degradation of organic matter was studied. Combined with the method of characterization and electrochemical analysis, the gas diffusion cathode method for phenol 2 was analyzed. The degradation mechanism of 4-dichlorophenol. The effect of gas diffusion cathode on the degradation of phenol was investigated. The optimum conditions for phenol degradation by gas diffusion cathodic method were as follows: current density 80 Ma / cm 2, electrolyte concentration 0.2 mol / L, fixed pH 4. The phenol can be completely degraded by electrolysis for 40 min ~ 50 mg/L, and the removal rate of COD of electrolytic 2 h can reach 91%. The results showed that the electrochemical catalytic activity of the electrode was good and the degradation of phenol was in accordance with the first-order reaction kinetics. The electrode was prepared by calcination at high temperature (600 鈩，

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