铁基非晶合金制备及偶氮染料降解性能研究

发布时间：2018-07-01 16:16

本文选题：铁基非晶合金 + 偶氮染料　；参考：《清华大学》2015年博士论文

【摘要】：最近两年来,部分铁基非晶合金被发现能作为零价铁对含偶氮染料的印染废水进行快速降解。尽管目前研究尚处于初始阶段,涉及铁基非晶合金的降解性能的众多问题还不清楚,但其展示出的优异的污水降解性能对工程应用具有很大吸引力,因此开展相关研究具有重要科学意义和实用价值。本研究以Fe-B二元非晶合金为基础,系统地研究了三种典型铁基非晶合金对偶氮染料降解反应的动力学过程、反应机理以及合金成分等因素对于铁基非晶合金降解性能影响。与相同成分的晶化条带以及300目还原铁粉相比,Fe-B二元非晶合金对偶氮染料直接蓝6的降解过程中,表现出更低的降解反应活化能和更高的降解速率。在相同实验条件下,Fe84B16非晶条带对直接蓝6降解反应的的表面积约化反应速率系数为同成分晶态条带与300目还原铁粉的1.8及89倍。分析表明,Fe-B二元非晶合金对偶氮染料降解机理同晶态材料相同,为还原降解偶氮染料。Fe-B二元非晶合金所具有的高的降解性能一方面是由于非晶态结构相对于晶态具备更高活性;另一方面是由于类金属元素硼在降解过程中在条带表面阻碍形成致密氧化层,促进降解反应进行。研究发现,Fe-Si-B非晶合金条带同样具备优异降解性能。相同条件下,工业Fe-Si-B非晶合金条带对直接蓝6、金橙II以及甲基橙降解反应的表面积约化反应速率系数分别为300目还原铁粉的60、1300以及37000倍。分析发现,Fe-Si-B非晶合金降解机理与Fe-B非晶合金相同,同样是由于非晶结构以及类金属元素的添加促使其具备高的降解能力。通过对Fe-Si-B非晶合金条带低温退火后机械粉碎所得粉末的降解性能的研究发现,虽然退火等工艺能在一定程度上提高降解反应活化能,但由于比表面积的增加,在相同用量下,不同粒径的非晶合金粉末对直接蓝6的表观反应速率系数为原始Fe-Si-B非晶条带2~10倍。同时,重复性实验结果显示,Fe-Si-B非晶合金粉末具有良好的重复利用性能,具有优异的应用前景。通过研究Finemet系列非晶合金对偶氮染料的降解性能发现,相同条件下,Finemet系列非晶条带对金橙II降解反应的表面积约化反应速率系数均为300目还原铁粉的100倍左右,但明显低于Fe-B以及Fe-Si-B非晶合金。分析发现金属元素的添加会增加条带表面氧化层致密性,阻碍还原降解反应,使降解机理转变为吸附降解为主。而通过研究过热条带降解性能发现,晶化相析出能有效破坏Finemet系列非晶合金表面氧化层致密性,提高Finemet非晶合金的降解能力。
[Abstract]:In the last two years, some Fe-based amorphous alloys have been found to be able to rapidly degrade azo dye containing printing and dyeing wastewater as zero-valent iron. Although the current research is still in its initial stage and many problems related to the degradation properties of Fe-based amorphous alloys are not clear, its excellent wastewater degradation performance is attractive for engineering applications. Therefore, it is of great scientific significance and practical value to carry out relevant research. Based on Fe-B binary amorphous alloys, the kinetic process of degradation of azo dyes by three typical Fe-based amorphous alloys was studied systematically, and the effects of reaction mechanism and alloy composition on the degradation properties of Fe-based amorphous alloys were studied. Compared with the crystallization strip of the same composition and 300 mesh reduced iron powder, the degradation process of azo dye direct blue 6 by binary amorphous alloy (Fe-B) shows a lower activation energy and a higher degradation rate. Under the same experimental conditions, the surface area reductive reaction rate coefficient of the amorphous band Fe84B16 for direct blue 6 degradation is 1.8 and 89 times higher than that of the same composition crystal band and 300 mesh reduced iron powder. The results show that the degradation mechanism of azo dyes by Fe-B binary amorphous alloys is the same as that of crystalline materials. On the other hand, the formation of dense oxide layer on the strip surface is hindered by boron-like elements in the degradation process, which promotes the degradation reaction. It was found that Fe-Si-B amorphous alloy strip also had excellent degradability. Under the same conditions, the surface reduction rate coefficients of the direct blue 6, gold orange II and methyl orange degradation reaction of industrial Fe-Si-B amorphous alloy were 60,1300 and 37000 times of those of the reduction of iron powder over 300 mesh, respectively. It is found that the degradation mechanism of Fe-Si-B amorphous alloy is the same as that of Fe-B amorphous alloy, which is also due to its high degradability due to the addition of amorphous structure and metal-like elements. The degradation properties of Fe-Si-B amorphous alloy after low temperature annealing were studied. It was found that the activation energy of degradation reaction could be improved to some extent by annealing, but due to the increase of specific surface area, the degradation activation energy could be increased in the same amount. The apparent reaction rate coefficient of amorphous alloy powder with different particle size to direct blue 6 is 210 times that of the original Fe-Si-B amorphous strip. At the same time, the reproducibility experiment results show that the Fe-Si-B amorphous alloy powder has good reuse performance and excellent application prospect. The degradation of azo dyes by Finemet series amorphous alloys was studied. Under the same conditions, the surface area reductive reaction rate coefficient of gold orange II degradation reaction with Finemet series amorphous strip was about 100 times of that of 300 mesh reduced iron powder. But it is obviously lower than Fe-B and Fe-Si-B amorphous alloys. It was found that the addition of metal elements would increase the densification of the oxidation layer on the strip surface, hinder the reduction and degradation reaction, and transform the degradation mechanism into adsorption degradation. It is found that the precipitation of crystallization phase can effectively destroy the densification of oxidation layer on the surface of Finemet series amorphous alloy and improve the degradation ability of Finemet amorphous alloy.
【学位授予单位】：清华大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：X791;TG139.8

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