氧化镁基固化剂对铅离子的吸附作用及其影响因素

Adsorption of Pb^(2+) on a magnesia-based curing agent and its influencing factors

应用批量平衡法,以膨润土、硅藻土和氧化镁为原料,探索了组配固化剂对Pb^(2+)的吸附性能、作用机制及影响因素,为将天然材料固化剂应用于重金属污染土壤修复提供理论参考。结果表明,组配固化剂对Pb2+的吸附行为符合二级动力学模型,等温吸附曲线符合Langmuir方程,吸附过程是自发、吸热反应,以物理吸附为主,30、40和50℃的最大吸附量分别为96.2、114.9和151.5 mg·g^(-1)。吸附过程受pH值和盐度的影响,膨润土、硅藻土与氧化镁混合,能有效提高对Pb^(2+)的吸附固化效果。

A magnesia-based curing agent was prepared using bentonite,diatomite,and magnesia with the help of the batch equilibrium method. Pb^（2＋） adsorption and its influential factors on securing a matching curing agent in aqueous solution were investigated. The sorption kinetic processes followed a pseudo-second-order kinetic model,as the isothermal data more closely followed a Langmuir model than a Freundlich or Tempkin model. The maximum Pb^（2＋） adsorption capacity to matching curing agent of 96. 2,114. 9,and 151. 5 mg·g^（-1）was observed at30,40 and 50 ℃,respectively. The apparent thermodynamic parameters（ ΔG^0,ΔH^0,and ΔS^0） indicated that the adsorption process was spontaneous,endothermic,and entropically unfavorable toward physisorption. The pH and calcium ion strength affected the adsorption,indicating that bentonite and diatomite promoted the adsorption effect of magnesia.