Experimental And Theoretical Studies On The Effect Of Fullerene C₆₀ On Sulfur Dioxide Hydrogen Peroxide

The significant increase of sulfate content during haze pollution is the key factor causing serious haze events.Hydrogen peroxide(H₂O₂),as the main oxidant of sulfate aerosol,plays an important role in the contribution of sulfate.Fullerene C₆₀,as a new type of atmospheric pollutant,mainly comes from the incomplete combustion of hydrocarbons.Therefore,exploring the effect of fullerene C₆₀on the oxidation of H₂O₂to sulfate has guiding significance for air pollution control.In order to study the effect mechanism of fullerene C₆₀on H₂O₂liquid-phase oxidation of SO₂,this paper carried out work through laboratory simulation and density functional theory.The specific contents and conclusions are as follows:(1)Laboratory simulation study:under laboratory conditions,fullerene stable aggregate n C₆₀was prepared by delayed stirring.By simulating the atmospheric cloud water environment and setting different fullerene C₆₀content,H₂O₂Content and p H conditions,the effects of fullerene C₆₀particles and stable aggregate n C₆₀on the oxidation of SO₂by H₂O₂to sulfate under different environmental conditions were studied,and the samples of fullerene C₆₀particles after reaction were characterized and analyzed.The experimental results show that fullerene C₆₀particles can significantly improve the formation of sulfate,and the promotion effect is negatively correlated with p H value and the addition of H₂O₂.In addition,n C₆₀colloid of stable suspension has no significant effect on the liquid-phase oxidation of SO₂.The characterization results show that the zeta potential of fullerene C₆₀particles presents a negative potential,and the system is unstable at p H 3-6.Fullerene can be used as an electron transfer receptor in the oxidation process.The quantitative experiment of free radicals found that fullerene C₆₀could promote the decomposition of H₂O₂to·OH and·O₂^-.Through FT-IR and XPS characterization,it is found that there is S(VI)on the surface of fullerene C₆₀after reaction,indicating that the effect of fullerene C₆₀on SO₂liquid-phase oxidation is a typical pre adsorption post oxidation process.(2)Density functional theory:in order to further explore the adsorption and oxidation process of fullerene C₆₀for SO₂,a molecular model of fullerene C₆₀,SO₂,H₂O₂,HSO₃^-,H₂SO₃and H₂O was constructed,and its surface electrostatic potential was analyzed to find the adsorption site.The adsorption process of H₂O and C₆₀molecules was calculated,and the charge transfer between them was analyzed.The adsorption of SO₂,H₂O₂,HSO₃^-,H₂SO₃and C₆₀molecules under explicit H₂O molecules are calculated respectively.The most possible adsorption configuration is found by comparing the adsorption energy.The single adsorption and common adsorption mechanism of H₂O₂and SO₂on C₆₀surface were calculated,and the heterogeneous reaction mechanism of H₂O₂oxidizing SO₂on C₆₀surface was calculated combined with the transition state theory.The results show that the six membered ring of C₆₀molecule is easy to interact with the negatively charged O atom,while the C-C bond center is negatively charged and easy to interact with the H atom of H₂O,H₂O₂,HSO₃^-,H₂SO₃and the S atom of SO₂;C₆₀molecules are electronegative in the presence of water molecules;H₂O₂decomposes on the surface of C₆₀to generate·OH,which further oxidizes SO₂to form HOSO₂molecular clusters.