Implications of the structure of cementitious wastes containing Pb(II), Cd(II), As(V), and Cr(VI) on the leaching of metals
2004; Elsevier BV; Volume: 34; Issue: 7 Linguagem: Inglês
10.1016/j.cemconres.2003.11.025
ISSN1873-3948
AutoresCheryl E. Halim, Rose Amal, Donia Beydoun, Jason Scott, Gary Low,
Tópico(s)Recycling and utilization of industrial and municipal waste in materials production
ResumoCement stabilisation has been widely applied for the immobilisation of heavy metal ions before their disposal in landfills. This paper investigated the microstructure of cementitious wastes containing Pb, Cd, As, and Cr using an electron probe microanalyser and examined the implications of the microstructure on the leaching of the metal ions. From the microstructure analysis, it was proposed that Pb, As, and Cr ions were homogeneously dispersed in the calcium silicate hydrate (C-S-H) matrix by adsorption or precipitation with calcium or silicate compounds present in the cement. However, Cd formed discrete Cd(OH)2 precipitates believed to be contained within the cement pores or adsorbed on the C-S-H matrix. The leaching of metals in the pH region of 6 to 8 decreased in the following order: Cr(VI)>Cd(II)>Pb(II)>As(V). This leaching trend was found to be influenced by the manner in which the metal ions were incorporated into the cement matrix.
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