Based on comparison of cadmium immobilization with 4 types of minerals originated from 14 places in Hunan Province,four kinds of natural and efficient remediation materials(including limestone from Yujiaao of Ningxiang County,low-grade manganese ore from Nanmuchong of Xiangtan County,bentonite from Mazongling of Taoyuan County,and sepiolite from Xingang of Shimen County)were selected.The kinetic rate of cadmium immobilization by these four natural minerals is in the following descending order:bentonite>limestone>sepiolite>manganese ore.The cadmium adsorption by four kinds of minerals increases as the initial cadmium mass concentration increases.With cadmium mass concentration no higher than 10.0 mg/L,the cadmium adsorption by these four minerals is in the following descending order:limestone>bentonite>manganese ore>sepiolite;with cadmium mass concentration exceeding 10.0 mg/L,the cadmium adsorption by these four minerals is in the following descending order:bentonite>limestone>manganese ore>sepiolite.The adsorption behavior follows Langmuir adsorption model,and the maximum adsorption capacities of bentonite,limestone,manganese ore and sepiolite are 29.38 mg/g,14.51 mg/g,9.67 mg/g and 5.27 mg/g respectively.With pH of solution within the range of 6 to 9,the removal efficiency of cadmium by four minerals is in the following descending order:limestone>bentonite>manganese ore>sepiolite.It is concluded that the cadmium immobilization with natural minerals is related to chemical composition of minerals,initial cadmium mass concentration,and pH value.
关键词
重金属污染/吸附剂/污染土壤/土壤修复/镉/天然矿物/修复剂/吸附性能/固持性能/矿物材料
Key words
heavy metal pollution/adsorbent/contaminated soil/soil restoration/cadmium/natural mineral/remediation agent/adsorption performance/immobilization/mineral material