Molecular Simulation Study On Adsorption Performance Of Carbon Materials With Different Pore Sizes And Functional Groups On Volatile Organic Compounds

With the development of society,the energy consumption is also increasing,especially the consumption of fossil fuels is increasing year by year.The emission of volatile organic compounds(VOCs)seriously threatens the ecological environment and people’s health.Adsorption method is widely used as a VOCs treatment technology due to its high efficiency and low energy consumption.In recent years,molecular simulation technology has been widely used in the adsorption and separation of carbon materials.Researchers have performed some experiments and simulations on the adsorption properties of carbon materials.Based on the model theory built by the predecessors,the molecular simulations of Grand Canonical Monte Carlo,molecular dynamics and other calculation methods were used to study the different pore sizes(0.902 nm,1.997 nm,3.000 nm and 4.000nm)and functional groups(carboxyl,Hydroxyl,amino and hydrogen)carbon materials for VOCs adsorption performance.First,the model and simulation method were verified by comparing molecular simulation data of nitrogen and methane with experimental data and IAST calculation data.The results show that the simulated adsorption isotherms are in good agreement with the experimental data and the separation coefficient of the nitrogen-methane mixed system is consistent with the IAST calculation results,which proves the accuracy and reliability of the molecular model and simulation method.Then,the adsorption isotherms,distribution density,capillary condensation phenomenon,the effective volume of the activated carbon model,the diffusion coefficient,and the intermolecular interaction energies of VOCs were studied in depth.We found that the larger the pore size,the greater the pressure for capillary condensation to occur during the adsorption of benzene,toluene,and acetone.VOCs have larger diffusion coefficients at pore diameters of 3.000 nm and 4.000 nm.Activated carbon with pore diameters of 0.902 nm and 1.997 nm have a stronger adsorption effect on VOCs with a lower concentration than 0.1P0.The addition of functional groups will reduce the effective volume of activated carbon,thereby limiting its maximum saturated adsorption capacity for VOCs.The addition of carboxyl and amino groups will reduce the threshold pressure of VOCs,while hydroxyl and hydrogen play the opposite role,which is not conducive to the purification of low-concentration VOCs.