纤维负载锰氧化物催化剂的制备及其室温降解甲醛性能研究
发布时间：2018-10-12 16:48
【摘要】：甲醛(HCHO)是室内主要污染物之一,主要来源于室内装修用的胶合板、细木工板、中密度纤维板和刨花板等人造板材。甲醛是世界卫生组织公认的致癌物之一,长期暴露在高浓度甲醛环境中对人的身体健康危害很大。所以,一直以来室内甲醛的去除都是环境工程领域的研究热点。目前室内甲醛的去除方法有物理吸附法、化学反应法、生物降解法、光催化及催化氧化法等,其中过渡金属氧化物因其价格低廉,氧化甲醛效果好且氧化过程无有害副产物生成而受到人们的青睐。在过渡金属氧化物中,锰氧化物对甲醛的氧化性能优异,甚至优于贵金属负载的催化剂材料。而纤维负载锰氧化物型催化材料因其成本低、效果好、易应用于实际等优点,近年来成为人们研究的焦点之一。本文选用过滤棉和丝瓜络两种纤维作为载体,通过氧化还原法制备了两种纤维负载锰氧化物的复合材料。研究了原料浓度、浸渍时间等制备条件对甲醛净化效果的影响。利用扫描电镜(SEM)、X射线衍射(XRD)、拉曼光谱(Raman)研究了制备的锰氧化物的形貌、晶型和物相,对纤维负载锰氧化物复合材料在室温下对甲醛的降解性能进行了测试,通过气相色谱(GC)分析甲醛降解后的产物,原位红外(in-situ FTIR)分析材料失活的机制。采用甲醇还原高锰酸钾(KMn O4)的方法,室温条件下原位制备了过滤棉负载锰氧化物(Mn Ox/PET)复合材料。研究了高锰酸钾浓度、甲醇浓度以及十六烷基三甲基溴化铵(CTAB)浓度对锰氧化物负载量的影响。Mn Ox/PET材料室温去除甲醛的性能测试结果表明,当甲醛浓度为105mg/m3时,Mn Ox/PET在2 h内将甲醛全部降解为二氧化碳。Mn Ox/PET材料的表征结果表明,制备的锰氧化物为无定形态与水钠锰矿型的混合物,形貌为100~200 nm尺寸的颗粒状。以载体丝瓜络为还原剂,高锰酸钾为氧化剂,在室温条件下振荡不同时间,制备了丝瓜络负载锰氧化物(Mn Ox/LF)复合材料。研究了高锰酸钾浓度和制备时间对材料去除甲醛活性的影响,获得室温下去除甲醛性能最优的材料。最优的制备条件是0.2 g KMn O4+20 m L水+0.2 g丝瓜络于摇床上室温下反应16 h。Mn Ox/LF材料室温下去除甲醛性能测试结果表明,当甲醛浓度为320 mg/m3时,Mn Ox/LF复合材料在5 h后对甲醛的去除率达90%以上,降解的甲醛全部氧化为二氧化碳。Mn Ox/LF材料的表征结果表明,丝瓜络上负载的锰氧化物颗粒尺寸为~50 nm,丝瓜络与高锰酸钾反应前后晶型结构发生了改变,表明其与高锰酸钾发生了氧化还原反应。此外,研究发现纤维负载锰氧化物复合材料降解甲醛的机制为载体的吸附于锰氧化物的氧化协同作用。
[Abstract]:Formaldehyde (HCHO) is one of the main indoor pollutants, mainly from plywood, woodboard, MDF and particleboard. Formaldehyde is one of the carcinogens recognized by the World Health Organization (WHO). Therefore, the removal of indoor formaldehyde has always been a research hotspot in the field of environmental engineering. At present, the removal methods of indoor formaldehyde include physical adsorption, chemical reaction, biodegradation, photocatalysis and catalytic oxidation, among which transition metal oxides are cheap. Formaldehyde oxidation is favored by people because of its good effect and no harmful byproducts in the oxidation process. Among transition metal oxides, manganese oxide has excellent oxidation performance for formaldehyde, even better than noble metal supported catalyst material. Because of its low cost, good effect and easy to be applied in practice, fiber supported manganese oxide catalytic material has become one of the focuses of research in recent years. In this paper, two kinds of fibers, filter cotton and luffa, were used as carriers to prepare manganese oxide composites by redox method. The effects of raw material concentration, impregnation time and other preparation conditions on the purification of formaldehyde were studied. The morphology, crystal form and phase of manganese oxide were studied by scanning electron microscope (SEM), X) (SEM), X ray diffraction (XRD), Raman spectroscopy. The degradation of formaldehyde in fiber supported manganese oxide composites at room temperature was tested. The products of formaldehyde degradation were analyzed by gas chromatography (GC) and the mechanism of material inactivation was analyzed by in situ infrared (in-situ FTIR). Filtration cotton loaded manganese oxide (Mn Ox/PET) composites were prepared by methanol reduction of potassium permanganate (KMn O 4) at room temperature. The effects of potassium permanganate concentration, methanol concentration and cetyltrimethylammonium bromide (CTAB) concentration on the loading amount of manganese oxide were studied. When formaldehyde concentration is 105mg/m3, Mn Ox/PET degrades all formaldehyde to carbon dioxide in 2 h. The results of characterization of Mn Ox/PET material show that the prepared manganese oxide is a mixture of amorphous form and sodium manganite type, and its morphology is 100 ~ 200 nm granular. Mn Ox/LF composites were prepared by oscillating at room temperature with luffa complex as reducing agent and potassium permanganate as oxidant. The effects of potassium permanganate concentration and preparation time on the formaldehyde removal activity of the materials were studied. The best material for formaldehyde removal at room temperature was obtained. The optimum preparation condition is 0.2 g KMn O 4 20 mL water 0.2 g luffa lucifera under the room temperature reaction 16 h.Mn Ox/LF material on the rocker. When formaldehyde concentration was 320 mg/m3, the removal rate of formaldehyde in Mn Ox/LF composite was more than 90% after 5 h, and all the degraded formaldehyde was oxidized to carbon dioxide. The results of characterization of Mn Ox/LF material showed that the content of formaldehyde was more than 90%. The grain size of manganese oxide loaded on the loofah was about 50 nm, and the crystal structure changed before and after the reaction with potassium permanganate, which indicated that it redox with potassium permanganate. In addition, the mechanism of degradation of formaldehyde by fiber supported manganese oxide composite was found to be the synergistic effect of adsorption on manganese oxide.
【学位授予单位】：北京建筑大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X51;O643.36
本文编号：2266869
[Abstract]:Formaldehyde (HCHO) is one of the main indoor pollutants, mainly from plywood, woodboard, MDF and particleboard. Formaldehyde is one of the carcinogens recognized by the World Health Organization (WHO). Therefore, the removal of indoor formaldehyde has always been a research hotspot in the field of environmental engineering. At present, the removal methods of indoor formaldehyde include physical adsorption, chemical reaction, biodegradation, photocatalysis and catalytic oxidation, among which transition metal oxides are cheap. Formaldehyde oxidation is favored by people because of its good effect and no harmful byproducts in the oxidation process. Among transition metal oxides, manganese oxide has excellent oxidation performance for formaldehyde, even better than noble metal supported catalyst material. Because of its low cost, good effect and easy to be applied in practice, fiber supported manganese oxide catalytic material has become one of the focuses of research in recent years. In this paper, two kinds of fibers, filter cotton and luffa, were used as carriers to prepare manganese oxide composites by redox method. The effects of raw material concentration, impregnation time and other preparation conditions on the purification of formaldehyde were studied. The morphology, crystal form and phase of manganese oxide were studied by scanning electron microscope (SEM), X) (SEM), X ray diffraction (XRD), Raman spectroscopy. The degradation of formaldehyde in fiber supported manganese oxide composites at room temperature was tested. The products of formaldehyde degradation were analyzed by gas chromatography (GC) and the mechanism of material inactivation was analyzed by in situ infrared (in-situ FTIR). Filtration cotton loaded manganese oxide (Mn Ox/PET) composites were prepared by methanol reduction of potassium permanganate (KMn O 4) at room temperature. The effects of potassium permanganate concentration, methanol concentration and cetyltrimethylammonium bromide (CTAB) concentration on the loading amount of manganese oxide were studied. When formaldehyde concentration is 105mg/m3, Mn Ox/PET degrades all formaldehyde to carbon dioxide in 2 h. The results of characterization of Mn Ox/PET material show that the prepared manganese oxide is a mixture of amorphous form and sodium manganite type, and its morphology is 100 ~ 200 nm granular. Mn Ox/LF composites were prepared by oscillating at room temperature with luffa complex as reducing agent and potassium permanganate as oxidant. The effects of potassium permanganate concentration and preparation time on the formaldehyde removal activity of the materials were studied. The best material for formaldehyde removal at room temperature was obtained. The optimum preparation condition is 0.2 g KMn O 4 20 mL water 0.2 g luffa lucifera under the room temperature reaction 16 h.Mn Ox/LF material on the rocker. When formaldehyde concentration was 320 mg/m3, the removal rate of formaldehyde in Mn Ox/LF composite was more than 90% after 5 h, and all the degraded formaldehyde was oxidized to carbon dioxide. The results of characterization of Mn Ox/LF material showed that the content of formaldehyde was more than 90%. The grain size of manganese oxide loaded on the loofah was about 50 nm, and the crystal structure changed before and after the reaction with potassium permanganate, which indicated that it redox with potassium permanganate. In addition, the mechanism of degradation of formaldehyde by fiber supported manganese oxide composite was found to be the synergistic effect of adsorption on manganese oxide.
【学位授予单位】：北京建筑大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X51;O643.36
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