State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan 430074, China.
State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan 430074, China.
Sci Total Environ. 2022 Jun 1;823:153723. doi: 10.1016/j.scitotenv.2022.153723. Epub 2022 Feb 9.
The arsenic (As) and selenium (Se) in fine particulate matter (PM) have attracted increasing attentions due to their health effects. However, the emission control of fine particulate-bound arsenic and selenium (fine particulate-bound As/Se) from coal-fired power plants still faces various challenges. Understanding the formation and characteristics of fine particulate-bound As/Se is crucial for developing specific control technologies. This study clarifies the formation mechanism, removal characteristics, and inhalation bioaccessibility of fine particulate-bound As/Se from industrial coal-fired power plants through methods including aerosol generation, As/Se speciation determination, and in vitro bioaccessibility testing. The findings demonstrated that PM from pulverized coal-fired (PC) boilers was enriched with As/Se in terms of concentration and mass distribution. Instead, As/Se was mainly distributed in PM from circulating fluidized bed (CFB) boilers. Limestone injection in CFB boilers promoted As/Se enrichment in coarse PM. Fine particulate-bound As was mainly formed by chemical adsorption of As vapors by Ca-minerals, while the formation of fine particulate-bound Se was closely related to active Ca-minerals and Fe-minerals. Furthermore, Ca-bound As was easy to remove by electrostatic precipitator (ESP) and the removal of physically adsorbed SeO(s) was difficult, which was caused by the specific resistivity of different mineral components. Importantly, finer particulate-bound As/Se posed higher inhalation bioaccessibility, following the order of PM ≥ PM > PM. In particular, Ca-bound Se in fine PM owned high bioaccessibility. Based on these findings, measures were proposed to suppress the formation of fine particulate-bound As/Se in the furnace and/or strengthen its removal in the post-combustion stage.
细颗粒物（PM）中的砷（As）和硒（Se）因其对健康的影响而引起了越来越多的关注。然而，燃煤电厂细颗粒物结合态砷和硒（细颗粒物结合态 As/Se）的排放控制仍然面临各种挑战。了解细颗粒物结合态 As/Se 的形成和特性对于开发特定的控制技术至关重要。本研究通过气溶胶生成、As/Se 形态测定和体外生物可及性测试等方法，阐明了工业燃煤电厂细颗粒物结合态 As/Se 的形成机制、去除特性和吸入生物可及性。研究结果表明，煤粉炉（PC）产生的 PM 中 As/Se 的浓度和质量分布均较高，而循环流化床（CFB）锅炉的 As/Se 主要分布在 PM 中。CFB 锅炉中石灰石的喷射促进了粗 PM 中 As/Se 的富集。细颗粒物结合态 As 主要是由 As 蒸气通过 Ca 矿物质的化学吸附形成的，而细颗粒物结合态 Se 的形成则与活性 Ca 矿物质和 Fe 矿物质密切相关。此外，Ca 结合态 As 容易被静电除尘器（ESP）去除，而物理吸附的 SeO(s)则难以去除，这是由于不同矿物质成分的比电阻不同所致。重要的是，更细的细颗粒物结合态 As/Se 具有更高的吸入生物可及性，其顺序为 PM≥PM>PM。特别是细 PM 中的 Ca 结合态 Se 具有较高的生物可及性。基于这些发现，提出了在炉膛内抑制细颗粒物结合态 As/Se 形成和/或在燃烧后阶段加强其去除的措施。
