活化方解石协同硫酸亚铁高效修复Cd/As复合污染土壤

Efficient remediation of Cd/As combined contaminated soil by activated calcite and ferrous sulfate

土壤中的Cd、As等重金属影响粮食安全,其中Cd/As复合污染土壤修复难度较大。通过室内模拟培养实验,研究机械力活化方解石协同硫酸亚铁钝化土壤中Cd/As的性能,并利用X射线衍射(XRD)、X射线光电子能谱(XPS)、扫描电子显微镜(SEM)/能谱(EDS)等方法进行机理研究。结果显示,活化方解石协同硫酸亚铁能维持较好的有效态As钝化效果,同时对土壤中有效态Cd的钝化率高达80%,机械力活化改变了方解石的结晶度和溶解活性,强化了方解石在土壤中缓释水解产生CO_(3)^(2-)与OH-的性能,CO_(3)^(2-)与土壤中有效态Cd形成稳定的碳酸盐结合态,OH-促进硫酸亚铁与土壤中的有效态As形成铁氧化物结合态。

Cd and As in soil is a threat to food security in China.Moreover,remediation of Cd/As combined contaminated soil is more difficult.In this study,the performance of mechanically activated calcite combined with ferrous sulfate to immobilize Cd/As in soil was studied by indoor simulated incubation experiment,and its passivation mechanism was studied by XRD,XPS,SEM/EDS.The results showed that the activated calcite combined with ferrous sulfate maintained a high level of effective As passivation,and the passivation rate of available Cd in soil was as high as 80%.Mechanical activation changed the crystallinity and dissolution activity of calcite,and enhanced the slow-release hydrolysis of calcite in soil to produce CO_(3)^(2-)and OH-.Cd in the soil formed a stable carbonate bound state when CO_(3)^(2-)was present,and As in the soil formed an iron oxide bound state when OH-was present.