State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100190, China.
State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China.
Environ Pollut. 2022 Jan 1;292(Pt A):118312. doi: 10.1016/j.envpol.2021.118312. Epub 2021 Oct 7.
Inhalation of respirable silica particles can cause serious lung diseases (e.g., silicosis and lung cancer), and the toxicity of respirable silica is highly dependent on its crystal form. Common combustion processes such as coal and biomass burning can provide high temperature environments that may alter the crystal forms of silica and thus affect its toxic effects. Although crystalline silica (i.e., quartz, tridymite, and cristobalite) were widely found at different temperatures during the burning processes, the sources and crystal transformation pathways of silica in the burning processes are still not well understood. Here, we investigate the crystal transformation of silica in the coal and biomass combustion processes and clarify the detailed transformation pathways of silica for the first time. Specifically, in coal burning process, amorphous silica can transform into quartz and cristobalite starting at 1100 °C, and quartz transforms into cristobalite starting at 1200 °C; in biomass burning process, amorphous silica can transform into cristobalite starting at 800 °C, and cristobalite transforms into tridymite starting at 1000 °C. These transformation temperatures are significantly lower than those predicted by the classic theory due to possibly the catalysis of coexisting metal elements (e.g., aluminum, iron, and potassium). Our results not only enable a deeper understanding on the combustion-induced crystal transformation of silica, but also contribute to the mitigation of population exposure to respirable silica.
吸入可吸入的二氧化硅颗粒会导致严重的肺部疾病（例如矽肺和肺癌），而可吸入二氧化硅的毒性在很大程度上取决于其晶体形态。常见的燃烧过程，如煤炭和生物质燃烧，可以提供高温环境，这些环境可能会改变二氧化硅的晶体形态，从而影响其毒性作用。尽管在燃烧过程的不同温度下都广泛存在结晶二氧化硅（例如石英、方石英和柯石英），但燃烧过程中二氧化硅的来源和晶体转化途径仍不清楚。在这里，我们研究了煤炭和生物质燃烧过程中二氧化硅的晶体转化，并首次阐明了二氧化硅的详细转化途径。具体来说，在煤炭燃烧过程中，无定形二氧化硅可以在 1100°C 时开始转化为石英和柯石英，而石英可以在 1200°C 时开始转化为柯石英；在生物质燃烧过程中，无定形二氧化硅可以在 800°C 时开始转化为柯石英，而柯石英可以在 1000°C 时开始转化为鳞石英。这些转化温度明显低于经典理论预测的温度，这可能是由于共存的金属元素（如铝、铁和钾）的催化作用。我们的研究结果不仅加深了对二氧化硅在燃烧过程中引起的晶体转化的理解，还有助于减轻人群暴露于可吸入二氧化硅的风险。
