三种具有不同比表面积的活性炭-椰壳基AC-C、粒状AC-P和竹基AC-B分别与四种热塑性前驱体(改性剂)-聚乙烯醇(PVA),羟基丙基纤维素(HPC),柠檬酸(CiA),含氟聚酰亚氨(FPI)混合后,在900℃热处理1h.通过氮气吸附法和扫描电镜对改性后活性炭的孔结构进行了表征.实验发现,热塑性树脂对活性炭AC-B的孔结构改性最显著;而另外三种改性剂PVA,HPC和CiA的改性结果使得AC-B的表面积降低,这是由于对其微孔结构改性效果不同所引起的:PVA可消除所有微孔,HPC可以有效消除极微孔,而CiA仅减少极微孔体积,但增加了超微孔体积.一方面,30%CiA的添加量,导致AC-B的外表面积增加了170%;另一方面,改性剂FPI通过增加极微孔,使其表面积增加达2倍之多.通过选择改性剂,能够改变活性炭基体中的微孔孔径分布,实际上是通过增加或减少其中的极微孔来实现.
Three activated carbons having different surface areas, coconut-shell based (AC-C), pelletized (AC-P)and bamboo-derived ( AC-B), were modified by mixing them with four thermoplastic precursors, poly ( vinyl alcohol)(PVA), hydroxy propyl cellulose (HPC), citric acid (CiA), and fluorine-containing polyimide (FPI) followed by heat treatment at 900℃ for 1 h. The porous structures of the modified activated carbons were characterized by nitrogen adsorption and SEM. It was found that the thermoplastic precursors modified the porous structure of AC-B more significantly compared with the other two, AC-P and AC-C. PVA, HPC, and CiA modification resulted in the reduction of surface area of AC-B, which is attributed to a different modification of the micropore structure; PVA eliminated all micropores, HPC eliminated ultra-micropores preferentially, and CiA decreased the volume of ultra-micropores, whereas it increased that of super-micropores. On one hand, the addition of 30 mass% CiA to AC-B resulted in an increase in external surface area by 170%. On the other hand, the modifier FPI increased the surface area by increasing ultra-micropores to approximately twice that of the original activated carbons. By the selection of modifier, the distribution of micropore size in the substrate-activated carbons can be modified, either by decreasing or by increasing ultra-micropores.
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