磷酸镁水泥对挥发型重金属Pb^(2+)、Cd^(2+)的固化效果及机理的研究

Study on the Solidification Performance and Mechanism of Magnesium Phosphate Cement with Volatile Heavy Metal Pb^(2+) and Cd^(2+)

利用磷酸镁水泥对Pb^(2+)、Cd^(2+)等挥发型重金属硝酸盐进行固化,采用X射线衍射(XRD)、X射线光电子能谱分析(XPS)、及扫描电子显微镜(SEM)等技术手段。研究挥发型重金属对磷酸镁水泥的浸出毒性、表面微观形貌、水化产物和元素分布的影响,以及磷酸镁水泥对Pb^(2+)、Cd^(2+)等挥发型重金属离子的固化效果和机理。结果表明:磷酸镁水泥对重金属固化效果Pb^(2+)>Cd^(2+),浸出毒性数值远低于国家标准;Pb^(2+)促进水化过程,Cd^(2+)抑制水化过程;Pb在磷酸镁水泥中主要以Pb^(2+)的形态存在,Cd主要以Cd^(2+)的形态存在,Pb^(2+)和Cd^(2+)分别与磷酸根生成相应的磷酸盐晶相并以此状态存在于硬化的磷酸镁水泥中。

MPC was used to Solidificate volatile heavy metal Pb2+and Cd2+.It was studied by means of X-ray iffraction(XRD),X-ray photoelectron spectroscopy(XPS)and scanning electron microscope(SEM).The leaching toxicity,surface microstructure,hydration products,and element distribution of MPC added heavy metal were discussed.Solidification performance and mechanism of MPC with volatile heavy metal Pb2+and Cd2+were discussed.Research shows that:the MPC on heavy metal Solidification effect of Pb2+>Cd2+;while the value of leaching toxicity is far lower than national standard requirements.Pb2+can promote the process,while Cd2+are opposite.Pb exist mainly in Pb2+in MPC,and Cd exist mainly in Cd2+.Pb2+and Cd2+respectively generate corresponding phosphate crystalline phases with phosphate group and are presented in hardened MPC.