Radical-Initiated Formation of Aromatic Organosulfates and Sulfonates in the Aqueous Phase
Radical-Initiated Formation of Aromatic Organosulfates and Sulfonates in the Aqueous Phase
复制标题
DOI：
10.1021/acs.est.0c05644
复制
发表时间：
2020-10-06
影响因子：
11.4
通讯作者：
Grassian, Vicki H.
中科院分区：
文献类型：
--
作者：
Huang, Liubin;Liu, Tongshan;Grassian, Vicki H.
最近在城市站点收集的环境气溶胶中观察到芳香族有机硫酸盐和磺酸盐。包括芳烃在内的人为挥发性有机化合物被认为是其在大气中的前体物，但这些化合物的形成机制仍然没有得到充分的了解。在本研究中，我们研究了苯甲酸与亚硫酸盐在Fe 3+存在下在不同条件下的水相反应。芳香族有机硫酸盐和磺酸盐[以下称为芳香族有机硫化合物（AOSC）]可在反应期间形成。测得的产率为7.3 +/-0.6%，表明AOSC的形成可能为苯甲酸在大气中的命运提供了另一条途径。AOSC的形成机理被认为是通过有机自由基中间体与硫氧自由基的结合，即SO 3-和SO 4-自由基。除了苯甲酸之外，其它单环芳族化合物（即，苯、甲苯、水杨酸、苯甲醇和苯酚）也可以经历类似的机制来产生各种AOSC。有趣的是，通过这一途径形成的AOSC可以保留母体芳烃的芳环，从而揭示了单环芳烃也可以作为大气中迄今未被认识到的AOSC前体的事实。我们的研究结果为大气中AOSC形成的潜在来源和途径提供了新的见解。
Aromatic organosulfates and sulfonates have recently been observed in ambient aerosols collected in urban sites. Anthropogenic volatile organic compounds including aromatics are considered as their precursors in the atmosphere, but the mechanism for the formation of these compounds is still not adequately understood. In the present study, we investigated the aqueous phase reactions of benzoic acid with sulfite in the presence of Fe3+ under various conditions. Aromatic organosulfates and sulfonates [hereafter called aromatic organosulfur compounds (AOSCs)] can be formed during the reaction. The yield was measured as 7.3 +/- 0.6%, suggesting that the formation of AOSCs may provide an additional pathway for the fate of benzoic acid in the atmosphere. The mechanism for AOSC formation is proposed to be through the combination of organic radical intermediates with sulfoxy radicals, that is, SO3- and SO4- radicals. In addition to benzoic acid, other monocyclic aromatics (i.e., benzene, toluene, salicylic acid, benzyl alcohol, and phenol) can also undergo analogous mechanisms to produce various AOSCs. Interestingly, AOSC formation through this pathway can retain the aromatic ring of parent aromatics, shedding light on the fact that monocyclic aromatics can also serve as the hitherto unrecognized precursors of AOSCs in the atmosphere. Our findings provide new insights into potential sources and pathways for AOSC formation in the atmosphere.