羟基磷灰石对铅锌矿区土壤吸附Zn2+、Cd2+的影响

为探究羟基磷灰石(HAP)对矿区土壤重金属的固化效果,采用吸附试验,研究施加HAP的铅锌矿区土壤对Cd~(2+)、Zn~(2+)的动力学吸附和等温吸附效果。结果表明:土壤对Cd~(2+)、Zn~(2+)的吸附量随Cd~(2+)、Zn~(2+)初始浓度的增加而增加;在酸性条件下,其吸附量随pH上升而上升;准二级动力学方程能很好地描述两者的吸附过程,土壤吸附能力随HAP的添加量增大而增强;在Zn—Cd共存体系中,当初始浓度为20mg/L时,土壤对Zn~(2+)、Cd~(2+)的吸附无明显差异,2种金属离子竞争力度小,随着初始浓度上升,竞争明显,对Zn~(2+)的最大吸附量能达到单一体系中的79%～87%,而Cd~(2+)的最大吸附量只有单一体系中的57%～72%,Zn~(2+)的竞争力优于Cd~(2+),Zn~(2+)对Cd~(2+)吸附产生严重的抑制。综上可知,HAP能提高矿区土壤的吸附性能,在Zn、Cd污染土壤中,更能提升土壤对Zn~(2+)的吸附固持能力。

Effect of Hydroxyapatite on Adsorption of Zn2+ and Cd2+in Lead-Zinc Mine Area Soils

To explore the effect of hydroxyapatite (HAP) on the solidification of heavy metals in mining areas, this study conducted the adsorption experiments to study the kinetic adsorption and isothermal adsorption of Cd²⁺ and Zn²⁺ in the soil of Pb-Zn mines with HAP. The results showed that the adsorption of Cd²⁺ and Zn²⁺ increased with the increase of initial concentrations of Cd²⁺ and Zn²⁺; under acidic conditions, the amount of adsorption increased with the increasing pH values; the quasi-second-order kinetic equation could well describe the adsorption process of Zn²⁺ and Cd²⁺, soil adsorption capacities increased with the addition of HAP. In the Zn-Cd coexistence system, when the initial concentration was <20 mg/L, the adsorption of Zn²⁺ and Cd²⁺ in the soil was not significantly different. The competitiveness of the two metal ions was small, and the competition was obvious as the initial concentrations increased. The maximum adsorption capacities of Zn²⁺reached 79%~87% in a single system, while the maximum adsorption capacities of Cd²⁺ was only 57%~72% in a single system. The competitiveness of Zn²⁺ was better than that of Cd²⁺, and Zn²⁺ seriously inhibited the adsorption of Cd²⁺. In summary, HAP could improve the adsorption performance of soil in the mining area, and enhance the adsorption and retention ability of soil to Zn²⁺ in Zn and Cd contaminated soils.