Elmes, Victoria K. and Coleman, Nichola J. (2021) Interactions of Cd2+, Co2+ and MoO42- ions with crushed concrete fines. Journal of Composites Science, 5 (2):42. ISSN 2504-477X (Online) (doi:https://doi.org/10.3390/jcs5020042)

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Abstract

Construction and demolition activities generate approximately two thirds of the world’s waste with concrete-based demolition material accounting for the largest proportion. Primary aggregates are recovered and reused, although the cement-rich fine fraction is underutilised. In this study, single metal batch sorption experiments confirmed that crushed concrete fines (CCF) are an effective sorbent for the maximum exclusion of 45.2 mg g-1 Cd2+, 38.4 mg g-1 Co2+ and 56.0 mg g-1 MoO42- ions from aqueous media. The principal mechanisms of sorption were determined, by scanning electron microscopy of the metal-laden CCF, to be co-precipitation with Ca2+ ions released from the cement to form solubility limiting phases. The removal of Co2+ and MoO42- ions followed a zero-order reaction and that of Cd2+ was best described by a pseudo-second-order model. The Langmuir model provided the most appropriate description of the steady state immobilisation of Cd2+ and Co2+, whereas the removal of MoO42- conformed to the Freundlich isotherm. Long equilibration times (>120 h), loose floc formation and high pH are likely to limit the use of CCF in many conventional wastewater treatment applications; although, these properties could be usefully exploited in reactive barriers for the management of contaminated soils, sediments and groundwater.

Item Type:	Article
Uncontrolled Keywords:	recycled, aggregate, cement, construction and demolition waste, cadmium, cobalt, molybdenum, heavy metals, sorbent
Subjects:	Q Science > QD Chemistry
Faculty / School / Research Centre / Research Group:	Faculty of Engineering & Science Faculty of Engineering & Science > School of Science (SCI)
Last Modified:	12 Mar 2021 12:33
URI:	http://gala.gre.ac.uk/id/eprint/31184

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