期刊
ENVIRONMENT INTERNATIONAL
卷 133, 期 -, 页码 -出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.envint.2019.105247
关键词
Green/sustainable remediation; Potentially toxic element; Arsenic leachability; Waste valorization/recycling; Hydration and polymerization; Precipitation chemistry
资金
- Hong Kong Research Grants Council [PolyU 15223517, E-PolyU503/17]
- University Research Facility on Chemical and Environmental Analysis (URFCE) of PolyU
Elevated level of arsenic (As) in marine sediment via deposition and accumulation presents long-term ecological risks. This study proposed a sustainable stabilization/solidification (S/S) of As-contaminated sediment via novel valorization of red mud waste, blast furnace slag and calcined clay mineral, which were selected to mitigate the increased leaching of As under alkaline environment of S/S treatment. Quantitative X-ray diffraction and thermogravimetric analyses illustrated that stable Ca-As complexes (e.g., Ca-5(AsO4)(3)OH) could be formed at the expense of Ca(OH)(2) consumption, which inevitably hindered the hydration process and S/S efficiency. The Si-29 nuclear magnetic resonance analysis revealed that incorporation of metakaolin for As immobilization resulted in a low degree of hydration and polymerization, whereas addition of red mud promoted Fe-As complexation and demonstrated excellent compatibility with As. Transmission electron microscopy and elemental mapping further confirmed the precipitation of crystalline Ca-As and amorphous Fe-As compounds. Therefore, red mud-incorporated S/S binder achieved the highest efficiency of As immobilization (99.9%), which proved to be applicable for both in-situ and ex-situ S/S of As-contaminated sediment. These results advance our mechanistic understanding for the design of green and sustainable remediation approach for effective As immobilization.
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