Kinetic study on elemental mercury release from fly ashes and hydrated fly ash cement pastes.
Kinetic study on elemental mercury release from fly ashes and hydrated fly ash cement pastes.
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DOI：
10.1016/j.chemosphere.2019.125028
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发表时间：
2020-02
期刊：
影响因子：
8.8
通讯作者：
Wen Du;Chao-yang Zhang;X. Kong;Y. Zhuo
中科院分区：
文献类型：
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作者：
Wen Du;Chao-yang Zhang;X. Kong;Y. Zhuo
采用自行研制的汞测量系统研究了粉煤灰和水化粉煤灰水泥浆体中元素汞（Hg0）的释放动力学。采用三种粉煤灰（FA）和普通波特兰水泥（OPC）配制水泥浆体。在标准固化28天后，将水合水泥浆（HCP）研磨成细粉用于汞排放测量。在粉煤灰和水化粉煤灰水泥浆体中均发现了可检测到的Hg0释放。结果表明，高温和湿HCP样品中毛细孔水的蒸发加速了Hg0的释放。Hg0从HCP粉末颗粒表面的解吸和Hg0从内部孔隙的迁移都有助于Hg0的释放。动力学计算表明，水化粉煤灰水泥水化产物对Hg0的固载作用不大，Hg0主要被水化产物物理包裹在HCP颗粒中。
The kinetics of elemental mercury (Hg0) release from fly ashes and hydrated fly ash cement pastes was investigated using a homemade Hg measurement system. Three types of fly ash (FA) and ordinary Portland cement (OPC) were used to prepare cement pastes. After standard curing for 28 days, the hydrated cement paste (HCP) was ground into a fine powder for Hg emission measurements. Detectable Hg0was found released from both fly ashes and hydrated fly ash cement pastes. The results show that elevated temperatures and evaporation of the capillary pore water in wet HCP samples accelerate Hg0release. Both desorption of Hg0from the particle surface of HCP powder and migration of Hg0from the inner pores contribute to Hg0release. The kinetic calculation indicates that the hydration products of hydrated fly ash cement have little immobilization effect on Hg0, which is mainly physically encapsulated in the HCP particles by hydration products.