Hurt, Andrew, Coleman, Aimee and Coleman, Nichola (2022) Interactions of Cr3+, Ni2+ and Sr2+ with crushed concrete fines. Crystals, 12 (5):717. ISSN 2073-4352 (Online) (doi:https://doi.org/10.3390/cryst12050717)

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Abstract

The underutilized cement-rich fine fraction of concrete-based demolition waste is a potential sorbent for aqueous metal ion contaminants. In this study, crushed concrete fines (CCF) were found to exclude 33.9 mg g-1 of Cr3+, 35.8 mg g-1 of Ni2+ and 7.16 mg g-1 of Sr2+ from ~1000 ppm single metal nitrate solutions (CCF:solution 25 mg cm-3) under static batch conditions at 20 °C after 3 weeks. The removal of Sr2+ followed a pseudo-second-order reaction (k2 = 3.1 x 10-4 g mg-1 min-1, R2 = 0.999), whereas, a pseudo-first-order model described the removal of Cr3+ (k1 = 2.3 x10-4 min-1, R2 = 0.998) and Ni2+ (k1 = 5.7 x 10-4 min-1, R2 = 0.991). In all cases, the principal mechanism of interaction was the alkali-mediated precipitation of solubility-limiting phases on the surface of the CCF. Four consecutive deionized water leaching procedures (CCF:water 0.1 g cm-3) liberated 0.53%, 0.88% and 8.39% of the bound Cr3+, Ni2+ and Sr2+ species, respectively. These findings indicate that CCF are an effective sorbent for the immobilization and retention of aqueous Cr3+ and Ni2+ ions, although they are comparatively ineffectual in the removal and sustained exclusion of Sr2+ ions. As is commonly noted with Portland cement-based sorbents, slow removal kinetics, long equilibrium times, associated release of Ca2+ ions, high pH and formation of loose floc may preclude these materials from conventional wastewater treatments. This notwithstanding, they are potentially suitable for incorporation into permeable reactive barriers for the containment of metal species in contaminated groundwaters, sediments and soils.

Item Type:	Article
Uncontrolled Keywords:	recycled; cement; concrete; demolition waste; chromium; nickel; strontium; heavy metals; sorbent
Subjects:	Q Science > QC Physics Q Science > QD Chemistry T Technology > TP Chemical technology
Faculty / School / Research Centre / Research Group:	Faculty of Engineering & Science Faculty of Engineering & Science > School of Science (SCI)
Last Modified:	23 May 2022 10:08
URI:	http://gala.gre.ac.uk/id/eprint/36342

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