【作者】 刘佳颖；

【导师】 赵斌元；

【作者基本信息】 上海交通大学 ， 材料学， 2010， 硕士

【摘要】 由于成型活性炭在工业生产以及生活的使用中较传统活性炭有更多的优势,受到越来越多的关注。而无粘结剂添加的成型活性炭其吸附以及强度的综合性能更优于普通活性炭,是活性炭发展的重要方向。活性炭成型后,较大的表观尺寸会引起吸附行为的变化。成型活性炭的吸附性能与传统的小尺寸活性炭完全不同,不能沿用各类测试小尺寸活性炭的标准以及方法。为了使成型活性炭能够更有效地被利用,本论文对无粘结剂成型活性炭的吸附性能进行了整体研究。在液相吸附实验中,选取碘和亚甲基蓝作为吸附质,分别测试成型活性炭对于小分子和大分子物质的吸附能力。在使用颗粒活性炭、长方形薄片型和蜂窝型无粘结剂成型活性炭进行一系列吸附实验后发现:成型活性炭的吸附性能要用一条吸附量-时间曲线来表示,并且孔结构相同的薄片炭的最小表观尺寸越大,饱和吸附值越低,饱和吸附时间越长,但颗粒炭和蜂窝炭的吸附结果不受表观尺寸影响,且蜂窝炭的吸附时间接近1mm厚薄片炭的吸附时间。这是因为成型活性炭的大尺寸使得吸附质扩散到吸附剂内部这一步骤成为了吸附的关键。吸附温度和搅拌速度对吸附性能的影响也是一个证据。在实验中我们还发现,成型活性炭对亚甲基蓝的吸附效果远小于碘吸附值,这是因为成型活性炭的孔径分布严重阻碍了亚甲基蓝的内扩散。薄片炭含较多微孔,中孔以及大孔数量较少,大尺寸的亚甲基蓝分子的内扩散很难进行。气相吸附实验使用添加粘结剂的蜂窝炭和不添加粘结剂的蜂窝炭以及薄片炭静态吸附氯仿、甲苯、四氯化碳和苯的饱和蒸汽,吸附结果同样使用吸附值-时间曲线表示。成型活性炭的表观尺寸对于气相吸附的影响与液相吸附相同,但无粘结剂蜂窝炭表面的酸性含氧官能团较少,其选择吸附性比添加粘结剂的蜂窝炭弱,适应于吸附成分复杂的挥发性有机气体。采用浓氨水浸渍处理后,无粘结剂蜂窝活性炭的部分孔道尤其是微孔被打通,增大了比表面积和微孔比例,表面含氧官能团数量明显减少,炭样表面向非极性转化,对于非极性四氯化碳气体的吸附性能得到大幅度提高。本实验所用此类无粘结剂成型活性炭无论是在液相还是气相环境中,对于小分子的物质的吸附能力均较强,应适合用于这类污染物的处理。在制备成型活性炭时,不能一味追求高比表面积而提高微孔的比例,应该根据吸附质的分子的大小制备孔径分布具一定比例的成型活性炭,这样才能达到最优化吸附效果。使用蜂窝炭是提高吸附速率较为有效的一种方法。在成型活性炭的吸附性能测试中,应先将炭样的最小表观尺寸统一,再进行测试。更多还原

【Abstract】 As the activated carbon monolith (ACM) had more advantages used in industrial production and daily life than the traditional activated carbon (AC), it had been paid closer attention. The overall performances of binder-less ACM, including adsorption and strength, outmatched the ordinary AC. So the study of binder-less ACM was an important development direction. The larger size of ACM would lead to changes in its adsorption property, which was completely different from the one of small size carbon. So the testing of ACM can not follow the various types of testing standards and methods of small size carbon. In order to make full use of ACM, we had to conduct a comprehensive study on the adsorption properties of ACM.The iodine and methylene blue were selected as adsorbates in the liquid phase adsorption experiments, used for testing the adsorption capacity to small molecules and macromelocules respectively. The granular activated carbon (GAC), the rectangular slice and honeycomb binder-less ACM were used as adsorbants. The results of series experiments showed that the adsorption property of ACM had to be expressed by an adsorption value-time curve, which was a better reflection. The adsorption properties of ACM to iodine and methylene blue were affected by the minimum size, and with the increase of size, much more time was needed to achieve equilibrium and saturation value is lower. However, the adsorption results of GAC and honeycomb binder-less ACM were not influenced and the equilibrium time of the honeycomb samples closed to the sample whose thickness was 1mm, because the mass transfer played an important role in adsorption process. The affections from adsorption temperature and stirring velocity were also evidences. We also had found that the adsorption value to methylene blue was much less than the iodine. The reason was that the pore size distribution was particularly prominent in ACM that the matching of aperture diameter and the target size.The binder-less ACM disc and honeycomb, as well as two kinds of activated carbon honeycomb monolith (ACHM) were used in gas adsorption to compare their adsorption capacity to saturated steam of chloroform, toluene, carbon tetrachloride (CTC) and benzene and the results were also showed by adsorption value-time curves. The experiments indicated that the influence from the apparent size in gas adsorption was the same as in liquid adsorption. The amount of acidic oxygen-containing functional groups on BACMs was less than that on normal ACMs. It meant that the selective adsorption of BACMs to VOCs was weaker. So BACMs were more suitable to absorb VOCs of complex ingredients than other ACMs. After ammonia impregnation, some pores especially the micropores in BACH had been opened. The proportion of SSA and micropore increased and the amount of oxygen-containing functional groups significantly reduced. As a result, the adsorption performance to non-polar VOCs had been improved a lot.The binder-less ACM used in this study had good removal efficiency on small molecules pollutants, whether in liquid or gas environment. During the preparation of ACM, we should not blindly pursue high specific surface area to increase the micropore proportion, but considering the pore size distribution as an important parameter. It must be the most optimal result. And the use of honeycomb ACM could improve the adsorption rate a lot. Samples of the same minimum size as produces should be used in the assessment of performance on ACM.更多还原