C60在模拟气溶胶中的光降解实验与理论计算
A combined experimental and computational investigation on photodegradation of C60 in diverse model aerosol liquid layer
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摘要: 燃烧及碳纳米材料的生产和处置过程中,均有可能产生富勒烯(C60)等纳米颗粒物.这些纳米颗粒物进入大气后,主要存在于气溶胶中.由于本身的共轭结构C60可以吸收紫外可见光发生光氧化转化,研究C60在气溶胶中的光转化对于评价其环境归趋具有重要意义.本研究以环己烷、甲苯和二氯甲烷等溶剂模拟气溶胶表面液体层,采用模拟日光实验和密度泛函理论(DFT)计算研究了C60在3种溶剂中的光化学转化.实验结果表明,C60在环己烷、甲苯和二氯甲烷中的光降解符合准一级动力学,光解速率常数分别为(0.80±0.01)×10-3、(3.80±0.02)×10-3、(14.80±0.20)×10-3 min-1.DFT计算结果表明,C60在3种溶剂中均可以通过光致产生1O2发生氧化反应.然而,仅在二氯甲烷中C60可以通过电子转移生成O2·-来促进C60的光转化.甲苯溶剂中激发态甲苯分子可以敏化C60产生C60·-从而加快C60的降解.理论计算结果有助于解释实验中C60在二氯甲烷中光解速率最快,在甲苯中光解速率比在环己烷中快的现象.Abstract: Fullerene (C60) nanoparticles can be produced during combustion, carbonaceous nanomaterials production and disposition. These nanoparticles mainly exist in aerosols when released to the atmosphere. Photo-oxidation is an important degradation process for C60 because of its conjugated structure and strong light-absorbing properties within the solar spectrum. Phototransformation of C60 in aerosols has important implications for its environmental fate. Herein, we performed simulated sunlight experiments and density functional theory (DFT) computations to investigate photochemical transformation of C60 in three solvents, cyclohexane, toluene and dichloromethane that were selected as model aerosol surface. The experimental results show that phototransformation of C60 in these organic phases can be described by first order kinetics, and the photodegradation rate constants of C60 in cyclohexane, toluene and dichloromethane were (0.80±0.01)×10-3, (3.80±0.02)×10-3, (14.80±0.20)×10-3 min-1, respectively. DFT calculation indicates 1O2 can be photogenerated in the three solvents and participates in the photodegradation of C60. However, O2·- can only be produced in dichloromethane through electron transfer from C60 to O2, and C60·- can be formed in toluene as a result of electron transfer from T1Toluene* to C60. The DFT calculation results can explain why the photodegradation rate constant of C60 in these solvents decreased in the order of k dichloromethane > k toluene > k cyclohexane.
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Key words:
- C60 /
- aerosols /
- phototransformation /
- O2· /
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- density functional theory
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[1] TIWARI A J, ASHRAF-KHORASSANI M, MARR L C. C60 fullerenes from combustion of common fuels[J]. Science of the Total Environment, 2016, 547:254-260. [2] HOWARD J B, MCKINNON T J, MAKAROVSKY Y, et al. Fullerenes C60 and C70 in flames[J]. Nature, 1991, 352:139-141. [3] YEGANEH B, KULL C M, HULL M S, et al. Characterization of airborne particles during production of carbonaceous nanomaterials[J]. Environment Science & Technology, 2008, 42(12):4600-4606. [4] UTSUNOMIYA S, JENSEN K A, KEELER G J, et al. Uraninite and fullerene in atmospheric particulates[J]. Environment Science & Technology, 2002, 36(23):4943-4947. [5] SANCHIS J, BERROJALBIZ N, CABALLERO G, et al. Occurrence of aerosol-bound fullerenes in the Mediterranean Sea atmosphere[J]. Environment Science & Technology, 2012, 46(3):1335-1343. [6] TIWARI A J, MORRIS J R, EJERANO E P, et al. Oxidation of C60 aerosols by atmospherically relevant levels of O3[J]. Environment Science & Technology, 2014, 48(5):2706-2714. [7] TIWARI A J, MARR L C. The role of atmospheric transformations in determining environmental impacts of carbonaceous nanoparticles[J]. Journal of Environmental Quality, 2010, 39(6):1883-1895. [8] HOU W C, JAFVERT C T. Photochemical transformation of aqueous C60 clusters in sunlight[J]. Environment Science & Technology, 2009, 43(2):362-367. [9] TALIANI C, RUANI G, ZAMBONI R, et al. Light-induced oxygen incision of C60[J]. Journal of the Chemical Society, Chemical Communications, 1993, 24:220-222. [10] SCHUSTER D I, BARAN P S, HATCH R K, et al. The role of singlet oxygen in the photochemical formation of C60O[J]. Chemical Communications, 1998, 22:2493-2494. [11] LEE J, YAMAKOSHI Y, HUGHES J B, et al. Mechanism of C60 photoreactivity in water:Fate of triplet state and radical anion and production of reactive oxygen species[J]. Environment Science & Technology, 2008, 42(9):3459-3464. [12] JUHA L, HAMPLOVAÁ V, KODYMOVÁ J, et al. Reactivity of fullerenes with chemically generated singlet oxygen[J]. Journal of the Chemical Society, Chemical Communications, 1994, 23:2437-2438. [13] HOU W C, JAFVERT C. Photochemistry of aqueous C60 clusters:Evidence of 1O2 formation and its role in mediating C60 phototransformation[J]. Environment Science & Technology, 2009, 43(14):5257-5262. [14] PIETA P, ZUKOWSKA G Z, DAS S K, et al. Mechanism of reductive C60 electropolymerization in the presence of dioxygen and application of the resulting fullerene polymer for preparation of a conducting composite with single-wall carbon nanotubes[J]. Journal of Physical. Chemistry C, 2010, 114(18):8150-8160. [15] SHEN L, JI H F, ZHANG H Y. A theoretical elucidation on the solvent-dependent photosensitive behaviors of C60[J]. Photochemistry and Photobiology, 2006, 3(82):798-800. [16] ROGGE W F, HILDEMANN L M, MAZUREK M A, et al. Sources of fine organic aerosol 2. Noncatalyst and catalyst-equipped automobiles and heavy-duty diesel trucks[J]. Environment Science & Technology, 1993, 27(4):636-651. [17] MCDOW S R, SUN Q R, VARTIAINEN M, et al. Effect of composition and state of organic-components on polycyclic aromatic hydrocarbon decay in atmospheric aerosols[J]. Environment Science & Technology, 1994, 28(12):2147-2153. [18] MCDOW S R, JANG M S, HONG Y, et al. An approach to studying the effect of organic composition on atmospheric aerosol photochemistry[J]. Journal of Geophysical Research Atmospheres, 1996, 101(14):19593-19600. [19] SCHUETZLE D, LEE F S C, PRATER T J, et al. Analysis of atmospheric aerosols[J]. Analytical Chemistry, 2008, 1:485-514. [20] RUOFF R S, TSE D S, MALHOTRA R, et al. Solubility of C60 in a variety of solvents[J]. Journal of Physical Chemistry, 1993, 97(13):3379-3383. [21] JAFVERT C T, KULKARNI P P. Buckminsterfullerene's (C60) octanol-water partition coefficient (Kow) and aqueous solubility[J]. Environment Science & Technology, 2008, 42(16):5945-5950. [22] FEILBERG A, NIELSEN T. Effect of aerosol chemical composition on the photodegradation of nitro-polycyclic aromatic hydrocarbons[J]. Environment Science & Technology, 2000, 34(5):789-797. [23] FEILBERG A, NIELSEN T. Photodegradation of nitro-PAHs in viscous organic media used as models of organic aerosols[J]. Environment Science & Technology, 2001, 35(1):108-113. [24] OHURA T. Environmental behavior, sources, and effects of chlorinated polycyclic aromatic hydrocarbons[J]. The Scientific World Journal, 2007, 7:372-380. [25] CARTIER A, RIVAIL J L. Electronic descriptors in quantitative structure-activity relationships[J]. Chemometrics and Intelligent Laboratory Systems, 1987, 1(4):335-347. [26] JI H F, SHEN L. Triplet excited state characters and photosensitization mechanisms of α-terthienyl:A theoretical study[J]. Journal of Photochemistry and Photobiology B:Biology, 2009, 94(1):51-53. [27] HEMELSOET K, VAN SPEYBROECK V, WAROQUIER M. A DFT-based investigation of hydrogen abstraction reactions from methylated polycyclic aromatic hydrocarbons[J]. Chem Phys Chem, 2008, 9(16):2349-2358. [28] BETOWSKI L D, ENLOW M, RIDDICK L. Calculation of electron affinities of polycyclic aromatic hydrocarbons and solvation energies of their radical anion[J]. Journal of Physical Chemistry A, 2006, 110(47):12927-12946. [29] FRISCH M J, TRUCKS G W, SCHLEGEL H B, et al. Gaussian 09, Revision A.02[P]. Gaussian, Inc., Wallingford C T, 2009. [30] TOMASI J, MENNUCCI B, CAMMI R. Quantum mechanical continuum solvation models[J].Chemical Reviews, 2005, 105(8):2999-3093. [31] BLOTEVOGEL J, BORCH T, DESYATERIK Y, et al. Quantum chemical prediction of redox reactivity and degradation pathways for aqueous phase contaminants:an example with HMPA[J]. Environmental Science & Technology, 2010, 44(15):5868-5874. [32] KALEDIN A L, HUANG Z Q, YIN Q S, et al. Insights into photoinduced electron transfer between[Ru(MPTY)2] 4+ (mptpy=4'(4-methylpyridinio)-2,2':6',2″-terpyridine) and[S2O8]2-:Computational and experimental studies[J]. The Journal of Physical Chemistry A, 2010, 114(21):6284-6297. [33] NAMAZIAN M, ALMODARRESIEH H A, NOORBALA M R, et al. DFT calculation of electrode potentials for substituted quinones in aqueous solution[J]. Chemical Physics Letters, 2004, 396(4-6):424-428. [34] KAVARNOS G J, TURRO N J. Photosensitization by reversible electron-transfer-theories, experimental-evidence, and examples[J]. Chemical Reviews, 1986, 86 (2):401-449. [35] ZHANG S Y, CHEN J W, QIAO X L, et al. Quantum chemical investigation and experimental verification on the aquatic photochemistry of the sunscreen 2-Phenylbenzimidazole-5-Sulfonic Acid[J]. Environment Science & Technology, 2010, 44(19):7484-7490. [36] 夏少武, 魏庆莉, 张书圣. C60-甲苯溶液溶剂化作用[J]. 物理化学学报, 1997, 13(11):1029-1033. XIA S W, WEI Q L, ZHANG S S. Studies on the solvation of fullerene (C60) in toluene medium[J]. Acta Physico-Chimica Sinica, 1997, 13(11):1029-1033(in Chinese).
[37] GALLAGHER S H, ARMSTRONG R S, LAY P A, et al. Solvent effects on the electronic spectrum of C60[J]. Journal of Physical Chemistry, 1995, 99(16):5817-5825. [38] HWANG Y L, YANG C C, HWANG K C. The spike in the C60·- ESR spectrum:Oxygen effect and negative temperature dependence of the C60O2·- isomerization rate[J]. Journal of Physical Chemistry A, 1997, 101(43):7971-7976. -

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