鐵系柱撐蒙脫土催化劑的制備及其降解苯酚廢水的研究
發(fā)布時間：2019-07-01 21:05
【摘要】：苯酚及其衍生物是化工和制藥行業(yè)的重要原材料,近年來隨著這兩個行業(yè)的不斷發(fā)展,酚類廢水的處理已成為社會關注的焦點問題。酚類分子結構穩(wěn)定、毒性高、可生化性差,傳統(tǒng)技術很難做到經(jīng)濟高效的降解。本文采用新興的非均相催化濕式過氧化氫氧化技術(CWPO),以代表物苯酚為研究對象,通過聚陽離子交換法制備系列鐵,鈰,鋁-柱撐蒙脫土催化劑(Fe,Ce,Al-MMT)降解苯酚廢水,重點優(yōu)化催化劑的結構和催化性能,針對性地解決廢水降解率低、柱撐催化劑易失活的問題。實驗考察了制備條件(柱化液Fe/Ce摩爾比、活性組分負載量、焙燒時間)對Fe,Ce,Al-MMT催化劑的影響。以CWPO降解苯酚廢水的效果參數(shù)(COD去除率、Fe離子溶出量)為指標評價了催化劑的活性及穩(wěn)定性；同時,以ICP、XRD、N_2吸附-脫附、FTIR、 DR UV-Vis、SEM和H_2-TPR等表征結果為依據(jù)分析了催化劑的微觀形貌和活性組分的存在形式。綜合可知,柱撐過程可以有效改性蒙脫土,當Fe/Ce摩爾比為7/3,活性金屬負載量為6%,焙燒溫度為450℃時,制備的Fe,Ce,Al-MMT催化劑性能較優(yōu),具有層間距高(doo1為2.649nm)、比表面積大(181.2m2/g)、活性組分含量多且分散性好、穩(wěn)定性強的特點。使用450℃-6%Fe,Ce,Al-MMT降解苯酚5h后,苯酚COD去除率可達94.48%,Fe離子溶出量僅為0.6528mg/L。將優(yōu)化得到的450℃-6%Fe,Ce,Al-MMT催化劑應用于CWPO降解苯酚廢水的研究。結合反應的動力學常數(shù),以溶液COD去除率、Fe離子溶出量為指標考察工藝條件(反應時間、催化劑投加量、催化劑入水pH)對苯酚降解的影響。結果表明,當反應溫度為60℃,催化劑投加量為1.0g/L,催化劑入水pH為5.0時,苯酚的降解效果較好(廢水的COD去除率達到94.48%,Fe離子溶出0.6528mg/L,表觀速率常數(shù)0.6529h-1)。此外,采用BET、SEM、DR UV-Vis等表征分析了單次使用后的450℃-6%Fe,Ce,Al-MMT催化劑,發(fā)現(xiàn)酸性反應介質并不會對催化劑的結構和活性組分產(chǎn)生較大的影響,并且連續(xù)五次重復使用回收的催化劑,苯酚的COD去除率僅下降6%,說明制備的催化劑穩(wěn)定性良好。實驗對CWPO降解苯酚廢水的機理進行研究,證明了HO·是非均相CWPO降解體系最主要的活性自由基,其生成速率受介質溶液pH的影響較大。建立的一級動力學模型與實驗數(shù)據(jù)的擬合率較高,計算去除COD的表觀活化能Ea=17.64KJ/mol。最后,在催化劑傳統(tǒng)制備法的基礎上進行改良以減少制備過程中的用水量,在不借助外場能量的前提下,分散介質由蒸餾水替換為介電常數(shù)較低的乙醇溶液,重點討論了不同分散介質對催化劑微觀結構和催化活性的影響。結果顯示,兩種方法所制備的催化劑性能相當,證明了該方法的可行性。
[Abstract]:Phenol and its derivatives are the important raw materials in the chemical and pharmaceutical industry. In recent years, with the development of these two industries, the treatment of phenolic wastewater has become the focus of social concern. The phenolic molecular structure is stable, the toxicity is high, the biodegradability is poor, and the traditional technology is difficult to achieve cost-effective degradation. In this paper, a new heterogeneous catalytic wet hydrogen peroxide oxidation technology (CWPO) was used to study the degradation of phenol wastewater by using a polycation exchange method to prepare series of iron, iron and aluminum-pillared montmorillonite catalysts (Fe, Ce, Al-MMT). The structure and the catalytic performance of the catalyst are optimized, and the problem of low degradation rate of the wastewater and easy deactivation of the column support catalyst is solved. The effects of preparation conditions (Fe/ Ce molar ratio, loading of active component and firing time) on the Fe, Ce and Al-MMT catalysts were investigated. The activity and stability of the catalyst were evaluated with the effect parameters of CWPO-degrading phenol wastewater (the removal rate of COD and the amount of Fe ion). At the same time, ICP, XRD, N _ 2 adsorption-desorption, FTIR, DR UV-Vis, The results of SEM and H _ 2-TPR were based on the analysis of the micro-morphology of the catalyst and the existence of the active components. It is known that the process of column support can effectively modify the montmorillonite, when the molar ratio of Fe/ Ce is 7/3, the loading of the active metal is 6%, and the roasting temperature is 450 DEG C, the prepared Fe, Ce, Al-MMT catalyst has the advantages of better performance, high layer spacing (doo1 of 2.649 nm) and large specific surface area (181.2 m2/ g), The active component has the characteristics of multiple content and good dispersivity and strong stability. The removal rate of phenol was 94.48% after 5 h of phenol degradation by 450 鈩，
本文編號：2508791
[Abstract]:Phenol and its derivatives are the important raw materials in the chemical and pharmaceutical industry. In recent years, with the development of these two industries, the treatment of phenolic wastewater has become the focus of social concern. The phenolic molecular structure is stable, the toxicity is high, the biodegradability is poor, and the traditional technology is difficult to achieve cost-effective degradation. In this paper, a new heterogeneous catalytic wet hydrogen peroxide oxidation technology (CWPO) was used to study the degradation of phenol wastewater by using a polycation exchange method to prepare series of iron, iron and aluminum-pillared montmorillonite catalysts (Fe, Ce, Al-MMT). The structure and the catalytic performance of the catalyst are optimized, and the problem of low degradation rate of the wastewater and easy deactivation of the column support catalyst is solved. The effects of preparation conditions (Fe/ Ce molar ratio, loading of active component and firing time) on the Fe, Ce and Al-MMT catalysts were investigated. The activity and stability of the catalyst were evaluated with the effect parameters of CWPO-degrading phenol wastewater (the removal rate of COD and the amount of Fe ion). At the same time, ICP, XRD, N _ 2 adsorption-desorption, FTIR, DR UV-Vis, The results of SEM and H _ 2-TPR were based on the analysis of the micro-morphology of the catalyst and the existence of the active components. It is known that the process of column support can effectively modify the montmorillonite, when the molar ratio of Fe/ Ce is 7/3, the loading of the active metal is 6%, and the roasting temperature is 450 DEG C, the prepared Fe, Ce, Al-MMT catalyst has the advantages of better performance, high layer spacing (doo1 of 2.649 nm) and large specific surface area (181.2 m2/ g), The active component has the characteristics of multiple content and good dispersivity and strong stability. The removal rate of phenol was 94.48% after 5 h of phenol degradation by 450 鈩，
本文編號：2508791
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