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Influence of lead and chromium ions as toxic heavy metals between AFt and AFm phases based on C(3)A and C(4)A(3)(S)over-bar

Title
Influence of lead and chromium ions as toxic heavy metals between AFt and AFm phases based on C(3)A and C(4)A(3)(S)over-bar
Author
심광보
Keywords
C(3)A; C(4)A(3)(S)over-bar; AFt phases; Lead; Chromium (III)
Issue Date
2014-12
Publisher
Korean ASSOC Crystal Growth
Citation
Journal of Ceramic Processing Research, 2014, 15(6), P.539-544
Abstract
Three calcium aluminate (C(3)A) and calcium sulphoaluminate (C(4)A(3)(S) over bar) as clinker minerals were synthesized to investigate the solidification/stabilization (S/S) mechanism of lead and chromium ions on cement matrix. Effects of AFt phases on S/S mechanism were analyzed using FT-IR, SEM-EDS and heat evolution. Lead and chromium leachability from solidified AFt phases was also investigated using the toxicity characteristic leaching procedure (TCLP) recommended by the U.S. Environmental Protection Agency (EPA). The results showed that clinker mineral types considerably affected the S/S mechanism of AFt and AFm phases incorporating chromium and lead ions. In the case of adding chromium, both AFt and AFm phases based C(3)A and C(4)A(3)(S) over bar allowed ionic substitution Cr3+ for the trivalent ion as Al3+ and CrO42- for SO42-. Moreover, chromate hydrocalumite [3CaO center dot Al2O3 center dot CaCrO4 center dot nH(2)O] was also observed. However, in the case of adding lead, it was found that when C(3)A and C(4)A(3)(S) over bar were hydrated, the formation of AFt and AFm phase based C(4)A(3)(S) over bar was faster than C(3)A. Especially, AFt phases and the calcium lead hydroxides (Ca[Pb(OH)(3)center dot H2O](2)) incorporating lead ions were formed during hydration of C(4)A(3)(S) over bar in the early stage compared to the C(3)A case. This showed that AFt and AFm phase based C(4)A(3)(S) over bar for S/S of lead were more effective than that of C(3)A.
URI
http://www.scopus.com/record/display.uri?eid=2-s2.0-84920873270&origin=inward&txGid=27da6b774f9d04a5555692a330d9a5f7
ISSN
1229-9162
Appears in Collections:
COLLEGE OF ENGINEERING[S](공과대학) > MATERIALS SCIENCE AND ENGINEERING(신소재공학부) > Articles
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