Immobilization of heavy metals in cementitious matrices

Cementitious materials (CMs) have been prepared from treated clay powder (TCP) and excess lime. For comparison, ordinary Portland cement (OPC) has also been used to see entrapment capacity of the CMs for target metal ions. Interestingly, cured CMs and cured OPC show the same infrared (IR) spectral characteristics. In this study, some toxic metal ions have been trapped in hardened CMs and OPC. All these ions shift the major ν3 band of silicate unit but to different extent. Finally, trapped ions have been leached with deionized water and acetate buffer. Samples leached with deionized water show maximum retention (∼99%) of ions, whereas when buffer solution is used to leaching, most of the ions except Cr2O72- (75–89%), show only 20–45% retention.