Heterogeneous conversion of SO2 on nano alpha-Fe2O3: the effects of morphology, light illumination and relative humidity
Heterogeneous conversion of SO2 on nano alpha-Fe2O3: the effects of morphology, light illumination and relative humidity
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SO2在纳米α-Fe2O3上的非均相转化：形貌、光照和相对湿度的影响
DOI：
10.1039/c9en00097f
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Zhang Liwu
中科院分区：
文献类型：
--
作者：
Li Kejian;Kong Lingdong;Zhanzakova Assiya;Tong Songying;Shen Ji;ong;Wang Tao;Chen Lu;Li Qing;Fu Hongbo;Zhang Liwu
赤铁矿是大气矿物气溶胶的重要组成部分之一，由于其形成过程和来源的不同，总是呈现出不同的形态。然而，颗粒形态对大气非均相反应的影响以及光照和水分的贡献却很少得到关注。利用漫反射红外傅立叶变换光谱（DRIFTS）研究了这些因素对SO2在不同形貌纳米α-Fe2O3颗粒上非均相转化的影响。结果表明，不同形状α-Fe2O3样品的非均相反应性有显著差异。与纳米囊状和空心纳米状α-Fe2O3相比，六边形纳米板状和团聚状α-Fe2O3具有更大的吸收SO2的能力，这可能是由于其活性位点丰富，BET表面积和孔径更大。此外，光照增强了SO2在4种纳米α-Fe2O3样品上的非均相转化；这可能是由于赤铁矿的半导体性质和相对较低的光强。此外，水分在一定范围内促进了六方纳米片状α-Fe2O3对SO2的非均匀吸收；然而，过多的水分不利于硫酸盐的形成。在本研究中提出了可能的机制。该研究将有助于理解大气非均质过程，并为大气模拟研究提供有用的参数。
Hematite is one of the most important components in atmospheric mineral aerosols, which always presents different morphologies due to its different formation processes and various sources. However, less attention has been paid to the influences of the particle morphologies on atmospheric heterogeneous reactions as well as the contributions from illumination and moisture. In the present study, the impacts of these factors on the heterogeneous conversion of SO2 on nano α-Fe2O3 particles with different morphologies were investigated in detail using in situ diffuse-reflectance infrared Fourier transform spectroscopy (DRIFTS). The results indicated that the heterogeneous reactivities were significantly different among four α-Fe2O3 samples with various shapes. Compared to the nanocapsule-like and hollow nanoring-like α-Fe2O3, hexagonal nanoplate-like and agglomerated nanoparticle-like α-Fe2O3 exhibited significantly greater uptake capacity of SO2 probably due to the abundant reactive sites and larger BET surface area and pore size. In addition, light illumination enhanced the heterogeneous conversion of SO2 on the four nano α-Fe2O3 samples; this might be due to the semiconducting property of hematite and comparatively low light intensity. Furthermore, moisture promoted the heterogeneous uptake of SO2 on hexagonal nanoplate-like α-Fe2O3 in appropriate range; however, excess moisture was unfavorable for sulfate formation. Possible mechanisms were proposed in the present study. This study would be helpful in understanding the atmospheric heterogeneous processes and provides useful parameters for atmospheric modelling studies.