Theoretical Studies On The Mixing Reactions Of Mineral Particles With Typical Carbonyl Compounds:A Mechanism Study

With the rapid development of the economy and the acceleration of urbanization,a large number of air pollutants are emitted into the atmosphere,and air components are becoming more and more complex,causing serious pollutions to the atmosphere.Also,human health is threatened by haze and photochemical pollution.Mineral particles and carbonyl compounds?CCs?are the main components in atmosphere.Mineral particles has a significant impact on radiative forcing and climate via providing a reaction site for atmospheric chemical reactions of CCs or mixing with CCs to form a mixing state.The interaction between mineral particles and CCs not only represents a viable formation pathway of aerosol but also results in unfavorable dispersion conditions and aggravates the regional air pollutions.Hence,it is necessary to investigate the mixing mechanisms of mineral particles with air pollutions,in order to better insight into the mixing state of atmospheric aerosols and to assess the impact on air quality.This study was carried out by VASP software package based on density functional theory?DFT?.The configurations and characteristics of the mixing states of?-quartz and SO_x,NO_x or ARL are constructed and investigated.The mechanisms of the formation for the heterodimer and heterotrimer complexes are elucidated to insight into the nature of the particle mixing reactions.The mixing mechanisms of photochemical oxidation products of acrolein with SiO₂ particles and the heterogeneous reaction of OH with acrolein are also studied.The main results of this paper are listed as follows:?1?The mixing ability of SiO₂ with inorganic compounds mainly depends on the strength of the interaction of the center atom of inorganic compounds and the surface of SiO₂,while SiO₂ mixed with acrolein?ARL?proceeds via only hydrogen bonding?HB?.The nucleation ability of SiO₂ is enhanced significantly from simultaneous existence of ARL and SO_x/NO_x.SiO₂ exhibits a high reactivity with SO₃ and acrolein?ARL?,proceeding an irreversible process.The mixing reactions of SO₂/NO_x and SiO₂ are reversible,but the binding is enhanced by ARL,which contributes to the dust aerosol nucleation process by binding to SO₂/NO_x and SiO₂.The charge density difference and natural bond orbital analysis show that carbonyl compound acts as both hydrogen bonding?HB?donors and acceptors,while inorganic compound is only HB acceptor.Our results reveal that the mixing state of mineral dust with anthropogenic pollutant is largely facilitated in area with rapid industrialization and urbanization,which could further influence climate and radiative forcing.?2?SiO₂ mixed with atmospheric oxidation products of acrolein also proceeds via hydrogen bonding?HB?,and the mixing ability mainly depends on the length of hydrogen bonds and the number of interactions.The mixing states are easily formed thermodynamically from acrolein atmospheric oxidation products and SiO₂,and the addition products exhibit a high reactivity with SiO₂ with the binding energy of-143.4 kJ/mol,which is lower than those of SO₃?-81.0 kJ/mol?and ARL?-68.5 kJ/mol?.The reaction mechanisms of acrolein attacked by OH radical on SiO₂ are further investigated.The results show that there are two pathways:OH-addition and H-abstraction.The ARL-SiO₂ mixing system is readily attacked by OH radicals and the reaction is irreversible due to the low energy barriers of OH radical addition and H abstraction pathways.The addition reaction of acrolein with OH radicals more easily occurs than the abstraction pathway on the SiO₂ particles.The pathway of OH radical addition to t the carbonyl group of ARL has a lowest energy barrier of-26 kJ/mol,implying the high mixing ability of the addition product of acrolein with SiO₂particles.