超临界CO_(2)作用下甲苯在活性炭中的脱附机理

Study on the desorption mechanism of toluene in activated carbon under supercritical CO_(2)

对吸附挥发性有机物(volatile organic compounds,VOCs)饱和的活性炭进行脱附再生,既可延长活性炭使用寿命,又可减少固体废弃物处理量。超临界CO_(2)脱附活性炭能够较好地克服传统的热处理法固有的缺陷,被认为是目前较有前途的方法,但脱附机理尚不明确。本文采用分子动力学模拟为研究手段,以甲苯的脱附过程为研究对象,研究了在活性炭纳米孔隙中超临界CO_(2)分子的扩散、CO_(2)分子与甲苯分子的相互作用、脱附后的甲苯分子在CO_(2)相中的扩散等行为,从分子层面揭示了超临界CO_(2)分子的强扩散性、CO_(2)分子与甲苯分子之间作用能的大小以及CO_(2)大幅度地改善甲苯的流动性在微观脱附机理中起决定性作用。

The regeneration of activated carbon saturated with VOCs(volatile organic compounds)can not only prolong the life of activated carbon,but also reduce the solid waste treatment capacity.Supercritical CO_(2) desorption method can overcome the inherent defects of traditional heat treatment and is considered to be a promising method at present,but the desorption mechanism is still unclear.In this paper,the diffusion of supercritical CO_(2),the interaction between CO_(2) and toluene,and the diffusion of toluene in the nanopores of activated carbon were studied using molecular dynamics simulation.The research results at the molecular level revealed that the strong diffusion of supercritical CO_(2),the interaction energy between CO_(2) and toluene,and CO_(2) greatly improving the fluidity of toluene played a decisive role in the micro desorption mechanism.