复合矿物材料钝化修复Cd污染土壤的淋滤实验研究

Study on leaching characteristics of cadmium from soil by composite mineral materials

将矿物肥料与人造沸石复配制成复合矿物材料,既有钝化修复,又有全元素补充作用,同时弥补单一土壤修复材料的短板。这里将不同配比的复合矿物材料添加到镉污染的农田土壤,通过淋滤实验探讨了淋滤液中Cd含量变化、Cd淋滤动力学及复配矿物材料配比与Cd淋出量之间的线性关系,以期为重金属污染土壤防治提供借鉴。结果表明:①相较于单一施用矿物肥料(K)或人造沸石(F),二者配施能够显著减少20%~25%Cd淋出量,达到相互增益的效果;②不同配比的淋滤实验中,Cd随时间释放的变化规律进行了动力学方程拟合,发现整个淋滤过程是以粒内扩散为主的多扩散机制控制的过程;③根据Cd日淋出量与不同比例复配矿物材料之间的线性相关,发现第1 d淋滤过程受人造沸石影响较大,第1.5 d~第7 d淋滤过程中矿物肥料起主要作用,第8 d~第18 d淋滤过程受两者相互影响。

The combination of mineral fertilizer and artificial zeolite into composite mineral materials has both passivation repair and full elemental supplementation,while making up for the short board of a single soil restoration material.In this study,different ratio composite mineral materials are added to cadmium-contaminated farmland soil to provide theoretical basis and technical supporting for the prevention and control of heavy metal contamination soil by leaching experiment to discuss the change of Cd content,Cd leaching kinetics,and the liner relationship between the ratio of compound mineral materials and the amount of Cd leaching.The result show that:1)Compared with a single application of mineral fertilizer(K)or artificial zeolite(F),the combined application of the two can significantly reduce the amount of Cd leaching by 20%~25%,and achieve the effect of mutual benefit;2)In leaching experiments with different proportions,the kinetic equations of the Cd release variation with time were fitted,and it was found that the entire leaching process was controlled by a multi-diffusion mechanism dominated by intragranular diffusion;3)According to the liner correlation between the daily leaching amount of Cd and different proportions of compound mineral materials,finding that the leaching process of d1(day 1)is greatly affected by artificial zeolite,d1.5~d7(day1.5~day7)the mineral fertilizer plays a major role in the leaching process,and the d8~d18(day8-day18)leaching process is affected by the mutual influence of the two.