精炼渣-粉煤灰基地聚合物固化重金属(Zn、Cd)机制研究

MECHANISM OF SOLIDIFICATION OF HEAVY METALS (Zn, Cd) BY LADLE FURNACE SLAG-FLY ASH BASED GEOPOLYMERS

为改善重金属污染,提高固体废弃物利用率,以精炼渣(LFS)和粉煤灰(FA)为原料,氢氧化钠与水玻璃作为碱激发剂,在碱激发条件下制备地质聚合物固化重金属Zn^(2+)、Cd^(2+)。研究Zn^(2+)、Cd^(2+)掺量对固化体强度的影响,通过浸出实验评价地质聚合物对Zn^(2+)、Cd^(2+)的固定效果,结合XRD、SEM-EDS、FT-IR、XPS等表征方法对固定机制进行研究。结果表明:精炼渣-粉煤灰基地质聚合物与Zn^(2+)、Cd^(2+)具有良好的相容性,含有1.0%Cd^(2+)固化体28 d的抗压强度可达到40.62 MPa,水化浸出实验中Zn^(2+)、Cd^(2+)固化率均在99.6%以上;Zn^(2+)、Cd^(2+)加入后固化体中不会有新相生成,且在固化过程中未发生化学价态变化。金属离子能有效地固定在精炼渣基地质聚合物中,主要通过物理包封、吸附作用,少量重金属离子则是通过化学键合,以Si—O—M和Al—O—M (M=Zn、Cd)的形式存在于固化体中。

To improve the pollution of heavy metals and increase the utilization rate of solid waste,this study prepared geopolymers for the solidification of Zn^(2+),and Cd^(2+)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 Zn^(2+)and Cd^(2+)doping on the strength of the cured body was investigated,and the immobilization effect of the geopolymer on Zn^(2+)and Cd^(2+)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 Zn^(2+)and Cd^(2+),the compressive strength of the cured body containing 1.0%Cd^(2+)for 28 d could reach 40.62 MPa,and the curing rate of Zn^(2+)and Cd^(2+)in the hydration leaching experiments was over 99.6%;there was no new phase generated in the cured body after the incorporation of Zn^(2+)and Cd^(2+),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.