Formation of brown carbon on Fe-bearing clay from volatile phenol under simulated atmospheric conditions
Formation of brown carbon on Fe-bearing clay from volatile phenol under simulated atmospheric conditions
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模拟大气条件下挥发性酚在含铁粘土上形成棕色碳
DOI：
10.1016/j.atmosenv.2020.117427
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发表时间：
2020
影响因子：
5
通讯作者：
Gu Cheng
中科院分区：
文献类型：
--
作者：
Ling Jingyi;Sheng Feng;Wang Yi;Peng Anping;Jin Xin;Gu Cheng
由于大气棕色碳对气候变化的潜在贡献，近年来引起了人们的广泛关注。据报道，溶解的Fe（III）物种可以作为一种有效的氧化剂，催化挥发性酚类物质的聚合，随后在气溶胶中形成大气BrC。由于大气中的铁通常与粘土矿物粉尘有关，因此含铁粘土矿物表面的酚类物质的转化对BrC的形成具有潜在的重要性。以愈创木酚为模型酚类物质，研究了在不同相对湿度下，愈创木酚在Fe（Ⅲ）改性蒙脱石上棕色炭的形成过程。对产物的光谱特征和组成进行了系统的表征。结果表明，界面FeOH_2是促进愈创木酚聚合的关键物种，RH对粘土表面酸性和愈创木酚的气固吸附有重要影响。中等RH（~33%）条件下BrC的生成量最大，种类最多，而较高RH（~100%）条件下聚合速率加快。由于气溶胶中的水分含量对表面Fe（III）物种的羟基化状态影响不大，这表明在不同条件下，粘土矿物粉尘中的Fe（III）对BrC的形成起着重要的催化作用。
Atmospheric brown carbon (BrC) has recently attracted great concerns due to its potential contribution to.climate change. It was reported that dissolved Fe(III) species can act as an efficient oxidant to catalyze the.polymerization of volatile phenol substances, subsequently forming atmospheric BrC in aerosols. Since Fe in the.atmosphere is commonly associated with clay mineral dusts, the transformation of phenol substances on Febearing.clay mineral surface is potentially important for BrC formation. In this study, taking guaiacol as the.model phenol substance, its brown carbon formation process was investigated on Fe(III) modified montmorillonite.under different relative humidities (RHs). The spectroscopic features and compositions of the produced.BrC were systematically characterized. The results demonstrated that the interface FeOH2þ is the key species to.promote the polymerization of guaiacol, and RH plays a significant role to influence the surface acidity of clay.and the gas-to-particle adsorption of guaiacol. The BrC was produced with the most abundance and variety under.moderate RH (~33%), while higher RH (~100%) accelerated the polymerization rate. Since aerosol moisture.content might not largely influence the hydroxylation states of the surface bearing Fe(III) species, it signifies the.importance of clay associated Fe(III) to catalyze the BrC formation in varied conditions Our study highlights the.importance of clay mineral dust on the formation of BrC, and reveals the brown carbon formation pathways.under environmentally relevant conditions.