【摘要】：近年來,PPCPs的生產(chǎn)和消費越來越多,大量PPCPs排入水環(huán)境中,嚴(yán)重影響人類的健康與安全。因此需要對此類污染物進行處理。本文采用電化學(xué)催化來降解水中的頭孢他啶,主要研究內(nèi)容如下：1.用5mol·L-1的HNO3對碳納米管進行純化,制備碳納米管電極,選用稀土元素Ce,通過電沉積的方法對碳納米管電極進行修飾。通過SEM、FTIR、XRD、XPS、塔菲爾曲線、循環(huán)伏安等對純化前后和修飾前后電極進行分析測試,發(fā)現(xiàn)修飾后鈰以CeO2形態(tài)存在,較未修飾電極有更強的催化活性。2.以修飾后的CeO2/MWCNT電極電解頭孢他啶溶液,考察電流密度、極間距、pH、支持電解質(zhì)濃度、初始濃度對去除率的影響,并對比未修飾電極的去除率。發(fā)現(xiàn)在電流密度為3.0mA·cm-2、極間距為1cm、pH為6、支持電解質(zhì)濃度為1.0g·L-1、初始濃度為1mol·L-1的條件下電解1h后,CeO2/MWCNT電極降解頭孢他啶的效率幾乎高達100%,而未修飾電極則只有34.6%。通過LC-MS分析其可能的降解路徑,斷裂氨基和羧基,進而斷裂碳碳鍵和碳氮鍵,然后生成酰胺類物質(zhì),轉(zhuǎn)化為有機酸和酮,最終被氧化為水和二氧化碳。3.考察了兩電極在不同影響因素下的電流效率,發(fā)現(xiàn)在前5min(?)(?)取得較高的電流效率,之后下降很快。CeO2/MWCNT電極的電流效率均大于未修飾電極。4.對兩電極在不同影響因素下的動力學(xué)模型進行研究,得到在電流密度、極間距、pH、支持電解質(zhì)濃度變化時未修飾電極降解頭孢他啶為零級反應(yīng),CeO2/MWCNT電極為二級反應(yīng)。改變頭孢他啶初始濃度,發(fā)現(xiàn)未修飾電極仍然符合零級反應(yīng)特征,而CeO2/MWCNT電極表現(xiàn)出一級反應(yīng)的特征。
[Abstract]:In recent years, PPCPs production and consumption more and more, a large number of PPCPs discharged into the water environment, seriously affect human health and safety. Therefore, such pollutants need to be treated. In this paper, electrochemical catalysis was used to degrade ceftazidime in water. The main contents are as follows: 1. Carbon nanotubes (CNTs) were purified by HNO3 of 5mol 路L-1 to prepare CNTs electrode. Rare earth element Ce, was used to modify CNTs electrode by electrodeposition. SEM,FTIR,XRD,XPS, Tafer curve, cyclic voltammetry and so on were used to analyze and test the electrode before and after purification and modification. It was found that the modified cerium existed in the form of CeO2 and had stronger catalytic activity than the unmodified electrode. The effects of current density, electrode spacing, pH, supporting electrolyte concentration and initial concentration on the removal rate of ceftazidime solution were studied with modified CeO2/MWCNT electrode, and the removal rate of unmodified electrode was compared. It was found that when the current density was 1cm, pH was 6, the concentration of supporting electrolyte was 1.0g 路L-1 and the initial concentration was 1mol 路L-1, the electrode spacing of 3.0mA cm-2, was 1cm, pH was 6, and the concentration of supporting electrolyte was 1.0g 路L-1. The degradation efficiency of CeO2/MWCNT electrode for ceftazidime was almost 100%, while that of unmodified electrode was only 34.6%. The possible degradation pathway is analyzed by LC-MS, which breaks the amino and carboxyl groups, then breaks the carbon-carbon bonds and carbon-nitrogen bonds, and then forms amides, which are converted into organic acids and ketones, and are eventually oxidized to water and carbon dioxide. 3. The current efficiency of the two electrodes under different influence factors is investigated. It is found that the current efficiency of the two electrodes in the pre-5min (?) The current efficiency of the CEO _ 2 / MWCNT electrode is higher than that of the unmodified electrode, and the current efficiency of CEO _ 2 / CEO _ 2 electrode is much higher than that of the unmodified electrode. The kinetic model of the two electrodes under different influence factors was studied. It was found that the degradation of ceftazidime by the unmodified electrode was a zero-order reaction and the CeO2/MWCNT electrode was a second-order reaction when the current density, the electrode spacing and the electrolyte concentration of pH, were changed. When the initial concentration of ceftazidime was changed, it was found that the unmodified electrode still accorded with the zero-order reaction, while the CeO2/MWCNT electrode showed the first-order reaction.
【學(xué)位授予單位】：北京化工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：X703

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本文編號：2469994