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

Journal of Composites Science

卷:5

VictoriaK. Elmes¹  NicholaJ. Coleman¹ 

[1] Faculty of Engineering and Science, University of Greenwich, Chatham Maritime, ME4 4TB Kent, UK;

关键词: recycled;    aggregate;    cement;    construction and demolition waste;    cadmium, cobalt, molybdenum, heavy metals, sorbent;   

DOI  :  10.3390/jcs5020042

来源: DOAJ

【 摘 要 】

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.

【 授权许可】

Unknown