Journal
CLEAN-SOIL AIR WATER
Volume 42, Issue 3, Pages 355-363Publisher
WILEY-BLACKWELL
DOI: 10.1002/clen.201200663
Keywords
Carbon sequestration; Compressive strength; Heavy metals; Magnesium oxide; Solidification; stabilization
Categories
Funding
- Business for Cooperative R&D between Industry, Academy, and Research Institutes [00045220]
- Korea Small and Medium Business Administration
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We developed a novel mixed binder of MgO (magnesia) and supplementary cementitious materials that can solidify sediments contaminated with heavy metals as well as store CO2 through mineral carbonation reactions. The optimal MgO-based binder consisted of MgO, lime (L), fly ash (FA), and blast furnace slag (BFS) with a formula of MgO0.5-(L-0.1-(FA(0.4)BFS(0.6))(0.9))(0.5). The binder exhibited a compressive strength of 11.9MPa, which was similar to that of Portland cement. Sequential extraction of treated sediments showed that the stabilization capacity of the MgO-based binder for heavy metals (Cu, Cd, Ni, Pb, and Zn) was two times higher than that of PC. Results also show that more than 50% of the stabilized heavy metals existed within very persistent solid phases that were not disintegrated during the final step of the sequential extraction procedure using a HNO3/HClO4/HF solution. The hydration products of MgO that contributed to strength development and metal stabilization included brucite (Mg(OH)(2)), magnesium-silicate-hydrates (M-S-H), and lansfordite (MgCO(3)5H(2)O). Lansfordite was a major carbonation product in the treated sediments. By use of thermogravimetric analyses, we found that 58kg of CO2 could be sequestrated within the solidified sediment when a ton of dredged sediment was treated.
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