Interactions of Cd2+, Co2+ and MoO42− Ions with Crushed Concrete Fines

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