Adsorption and desorption performance of benzene series of honeycomb activated carbon and the effects of water vapor
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摘要:
以市售蜂窝活性炭为吸附材料,通过氮气吸附等温线和扫描电镜分析活性炭的比表面积、孔径分布和表面孔结构形貌,以评估活性炭吸/脱附苯系物的性能。利用动态吸附评价装置和气相色谱系统评价苯浓度、流速、不同苯系物流经蜂窝活性炭对其吸附容量的影响,并通过程序升温技术研究蜂窝活性炭脱附温度曲线。同时考察了水汽对蜂窝活性炭吸附容量、脱附温度曲线的影响。结果表明:蜂窝活性炭对苯系物的单位饱和吸附容量顺序为二甲苯>甲苯>苯,单位饱和吸附容量为66.5~138.1 mg/g,这可能是因为苯系物的分子尺寸效应影响了吸附容量。苯系物的最佳脱附温度基本维持在175 ℃。水汽的竞争吸附作用可以显著抑制苯的单位饱和吸附容量,引入1.8%的水汽后苯的饱和吸附容量降低了36.3%,这表明水汽占据了部分吸附位点,显著降低了苯的吸附容量。
Abstract:In order to evaluate the performance of activated carbon adsorption and desorption of benzene series, taking the commercial honeycomb activated carbon as the adsorption material, the specific surface area, aperture distribution and surface pore structure morphology of the activated carbon were analyzed by nitrogen adsorption isotherm and scanning electron microscope. The effects of benzene concentration, benzene flow and benzene species flowing through honeycomb activated carbon on their adsorption capacity were evaluated by dynamic adsorption evaluation device and gas chromatography system. The desorption temperature curve of honeycomb activated carbon was also studied by temperature programmed technology. At the same time, the effects of water vapor on honeycomb activated carbon adsorption capacity and desorption temperature curve were investigated. The results showed that the unit saturation adsorption capacity of honeycomb activated carbon to benzene species followed the sequence of xylene > toluene > benzene, with the values varied from 66.5 to 138.1 mg/g. The reason for different adsorption capacities maybe due to the molecular size effect of benzene species. The optimal desorption temperature of benzene species was basically maintained at 175 ºC. The competitive adsorption effect of water vapor could significantly inhibit the unit saturation adsorption capacity of benzene, which was reduced by 36.3% after the introduction of 1.8% water vapor, as the adsorption sites were partly occupied of by water vapor, significantly reducing the adsorption capacity of benzene.
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Key words:
- honeycomb activated carbon /
- adsorption capacity /
- desorption temperature /
- benzene series /
- water vapor
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