Application Of The Monte Carlo Simulation On The Study Of Adsorption Of Indoor Air Pollutants

Clean air is an essential to human.Air cleaning technologies provides a powerful tool for indoor air quality control.So far adsorption is still the most feasible and reliable technique for the removal of indoor air pollutants.This thesis aims at unravelling the mechanisms of adsorption of common indoor air pollutants at molecular level through Monte Carlo molecular simulation instead of the conventional modeling.The major contributions and innovations of thesis are:(1)Providing a systematic comparison between the conventional mechanistic models for adsorption equilibrium(capacity)and kinetics(transport),which are the two key ingredients needed for a complete understanding of adsorption,and molecular simulation,which is a powerful tool to overcome the limitations of the conventional models by providing the details at molecular level that are intractable for trial-and-error experiments or the conventional modeling to access.(2)Developing the averaged solid–fluid potential energies for layers and solids of various geometries and dimensionalities with the aid of advanced mathematical software,which would save enormous amount of computational time.(3)Conducting a comprehensive simulation study on a simple adsorption system,i.e.,adsorption of non-polar molecule on a non-porous surface.The 2D phase diagram and the evolution of heat spike with respect to temperature were obtained,which are in good agreement with experiments,by the grand canonical Monte Carlo simulations.Using various microscopic analysis,the mechanism of the observed behaviors was explained,i.e.,the balance of entropic and enthalpic contributions between the first and second layer adsorption.(4)Conducting a comprehensive literature review of the experimental and theoretical studies over past 50 years on the adsorption of water on carbonaceous materials.Based on which,a mechanism for water adsorption,centered on the formation-growth-coalescence of water clusters was proposed.(5)Based on the review,adsorption of water was extensively studied by molecular simulation.The Type V adsorption-desorption isotherm of water was firstly obtained in a simple slit-pore model.More importantly,the clustering-mediated mechanism of water adsorption was observed,in conformity with proposed mechanism in the review.(6)Based on the pore model developed for water,good agreement of formaldehyde isotherm between experiments and simulation was obtained for the first time.By conducting a comprehensive set of simulations on water,ammonia,and formaldehyde,which are all polar molecules but with different polarities,the underlying mechanism of adsorption was elucidated in terms of two fundamental driving forces of adsorption,adsorbate-adsorbent interaction,adsorbate-adsorbate interaction,and their balances with respect to different temperatures.