MECHANISM OF SOLIDIFICATION OF HEAVY METALS(Zn,Cd)BY LADLE FURNACE SLAG-FLY ASH BASED GEOPOLYMERS
To improve the pollution of heavy metals and increase the utilization rate of solid waste,this study prepared geopolymers for the solidification of Zn2+,and Cd2+under alkaline excitation conditions using ladle furnace slag(LFS)and fly ash(FA)as raw materials,and sodium hydroxide and water glass as alkaline activator.The effect of Zn2+and Cd2+doping on the strength of the cured body was investigated,and the immobilization effect of the geopolymer on Zn2+and Cd2+was evaluated by leaching experiments,and the immobilization mechanism was investigated by combining the characterization methods such as XRD,SEM-EDS,FT-IR,and XPS.The results showed that the LFS-FA-based geopolymer has good compatibility with Zn2+and Cd2+,the compressive strength of the cured body containing 1.0％Cd2+for 28 d could reach 40.62 MPa,and the curing rate of Zn2+and Cd2+in the hydration leaching experiments was over 99.6％;there was no new phase generated in the cured body after the incorporation of Zn2+and Cd2+,and no chemical valence change occurred during the curing process.Metal ions can be effectively fixed in ladle furnace slag base polymer,mainly through physical encapsulation,and adsorption,while a small number of heavy metal ions exist in the curing body in the form of Si—O—M and Al—O—M(M=Zn,Cd)through chemical bonding.
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