碳纳米管内水吸附行为及等量吸附热的巨正则Monte Carlo模拟  

Grand Canonical Monte Carlo Simulation Study of Water Adsorption Behavior and Isosteric Adsorption Heat in Carbon Nanotubes

作　　者：刘晨 刘忠军 赵明慧 敖庆波[2] LIU Chen;LIU Zhongjun;ZHAO Minghui;AO Qingbo(School of Materials Science and Engineering,Xi’an Shiyou University,Xi’an,shaanxi 710065,China;Northwest Institute for Nonferrous Metal Research,State Key Laboratory of Porous Metal Materials,Xi’an,shaanxi 710016,China)

机构地区：[1]西安石油大学材料科学与工程学院,陕西西安710065 [2]西北有色金属研究院金属多孔材料国家重点实验室,陕西西安710016

出　　处：《计算物理》2024年第2期203-213,共11页Chinese Journal of Computational Physics

基　　金：西安石油大学校青年创新团队项目(2019QNKYCXTD12);陕西省教育厅科学研究计划服务地方专项(20JC028)资助。

摘　　要：采用巨正则蒙特卡罗方法对单壁碳纳米管-水吸附体系进行计算模拟,通过对吸附和脱附等温线、局部密度分布、等量吸附热等进行表征,系统研究298 K时孔长、孔径以及表面强度对孔隙内水吸附行为的影响。结果表明:孔径效应对孔内水吸附行为影响显著,随着孔径逐渐增大,水分子先后以单链水、双链空心水环、水团簇的排列状态在孔内完成吸附。孔长在4~8 nm范围内时,随着孔长变大,发生吸附的初始压力越来越小,但当孔长增加到10 nm时,其对初始吸附压力的影响不再明显。最后,随着表面强度增大,发生水吸附的初始压力越来越小;同时,较小表面强度水分子的毛细蒸发相变过程瞬间完成,而当表面强度提高到40 K时,毛细蒸发相变过程则呈现出连续、逐渐完成的特点。In this work,water adsorbed in single-walled carbon nanotube(SWCNT)is simulated by the Grand Canonical Monte Carlo(GCMC)method.The effects of pore length,pore size and surface strength on water adsorption behaviors at 298 K are systematically studied,via the characterization of isotherms,local density distribution and isosteric heat.There are hysteresis loops observed for water adsorbed and desorbed in SWCNTs with relatively large pore radii(PR=0.8,1.0 nm),and the hysteresis loop disappears as the pore radius decreases to 0.55 nm.In addition,the water molecule packing manners are in the arrangement form of single chain,double helix chain and water clusters due to the pore size effects.When the pore length is in the range of 4~8 nm,the initial adsorption pressure becomes smaller and smaller as the pore length increases,but this effect rule gradually disappears with increasing pore length to 10 nm.Finally,the initial pressure of water adsorption decreases with surface strength;and when surface strengths are 20,28,32 K,the capillary evaporation phase transitions completed instantaneously.While the surface strength increases to 40 K,the capillary evaporation phase transition is shown gradually desorbed steps.As surface strengths increased from 20 K to 40 K,the isosteric adsorption heat at the pressure points of capillary condensation phase transition is 127.47,117.98,84.04,59.16 kJ·mol-1,respectively.

关 键 词：碳纳米管 吸附作用 蒙特卡罗模拟 等量吸附热 相变 

分 类 号：TQ021.2[化学工程]