Releasing Behavior of Mercury from Fly Ashes and Hydrated Fly Ash Cement Pastes

被引：0
|
作者：
Du W. [1 ]
Zhang C. [1 ]
Kong X. [1 ]
Zhuo Y. [2 ]
机构：
[1] Institute of Building Materials, Department of Civil Engineering, Tsinghua University, Beijing
[2] Key Laboratory of Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing
来源：
Kuei Suan Jen Hsueh Pao/Journal of the Chinese Ceramic Society | 2019年 / 47卷 / 08期
关键词：
Fly ash; Hardened cement paste; Mercury; Releasing behavior;
D O I：
10.14062/j.issn.0454-5648.2019.08.13
中图分类号：
学科分类号：
摘要：
Three kinds of fly ashe were selected to prepare cement pastes via mixing ordinary Portland cement (OPC) with the same amount of fly ash. Cement pastes were prepared at a fixed water to the blend cement ratio of 0.4. After curing for 28 d, the hardened cement pastes (HCP) were ground into fine powders. The releasing behavior of elemental mercury (Hg0) from the fly ash and the powdered HCP was analyzed by a homemade Hg measurement system. Detectable Hg0 was found to be released from both fly ashes and hydrated fly ash cement pastes during 90-d period. The Hg release amount of fly ashes at room temperature is 39.7 ng/g fly ash at the maximum during 90-d period. In contrast, the Hg release amount of the HCPs is 18.5 ng/g HCP at the maximum. The Hg release kinetics of HCPs and FAs are similar, indicating that the hydration products of cement present little immobilization effect on Hg0. The Hg releasing behavior from FA and HCP samples indicates that the hydration product of the HCP only has effects on the dilution and physical encapsulation of Hg0. The chemical immobilization of Hg0 by C-S-H does not occur. The Hg0 release rate is affected by the intragranular diffusion process and the desorption process from the granule surface. Elevated temperature and increased moisture content both can accelerate the Hg0 release. © 2019, Editorial Department of Journal of the Chinese Ceramic Society. All right reserved.
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页码：1116 / 1122
页数：6
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