Simulation Study On The Influence Mechanism Of Typical Modification Methods On The Adsorption Of Benzene By Carbon Materials

In recent years,the indoor environment has been seriously polluted by VOC,especially benzene pollution,which needs to be dealt with urgently.Carbon material adsorption has become the main force in benzene treatment due to its advantages of low cost,high efficiency,and strong maneuverability.The introduction of oxygen functional groups and nitrogen doping can enhance the adsorption properties of carbon materials,but from a microscopic perspective,it is revealed that the type of action of the two on benzene and carbon materials in indoor air and the mechanism of adsorption strength are not clear,and the competitive adsorption effects of benzene and water have yet to be explored.Based on density functional theory,this paper uses quantum chemistry to simulate the effects of oxygen functional group and nitrogen doping on the properties of carbon materials,including electrostatic potential,polarity,Van der Waals potential,etc.Analyze the adsorption energy,charge transfer,reduced density function,energy decomposition,etc.On the basis of exploring the mechanism of the influence of oxygen functional groups and nitrogen doping on the adsorption of benzene and water,the mechanism of competitive adsorption of benzene and water is revealed.The simulation results were verified by modifying activated carbon and performing benzene adsorption experiments.Studies have shown that both oxygen functional groups and nitrogen doping can break the uniform electrostatic potential distribution on the surface of carbon materials and change their polarity.Compared with edge adsorption,benzene tends to be adsorbed in a plane,and the dispersion interaction is the main one.The oxygen functional group hardly changes the Van der Waals potential distribution of the carbon material,causing it to have no obvious effect on the adsorption effect of benzene.Nitrogen doping can increase the negative Van der Waals potential area of carbon materials,thereby enhancing the adsorption of benzene.The two modification methods mainly affect the adsorption of water on the carbon material by enhancing the electrostatic interaction.The strong weak interaction such as the formation of hydrogen bonds between the carboxyl group and water occupies the adsorption site,thereby inhibiting the adsorption of benzene.The ether group has the opposite effect.Increasing hydrophobic groups such as ether groups and reducing hydrophilic groups such as carboxyl groups will help activated carbon adsorb benzene under water conditions.Under water conditions,the doped pyridine nitrogen and pyrrole nitrogen can enhance the adsorption of benzene.Graphite nitrogen is hydrophobic,and the mechanism of adsorption of benzene is the same as that of ether group.Among the various forms of nitrogen co-doped carbon materials,the adsorption effect of carbon materials on water has not been weakened,and the adsorption of benzene is strengthened while adsorbing water.This provides a theoretical basis for the preparation of nitrogen-doped active carbon adsorbents.In this study,by simulating the adsorption of benzene and water on carbon materials,the microscopic mechanism is revealed,and the types of oxygen-containing functional groups that contribute to the adsorption of benzene are determined.The relevant research on nitrogen doping has established its promotion effect on benzene adsorption.This research provides theoretical support for the preparation of high-efficiency carbonaceous adsorbents for benzene in indoor air.