磁性纳米羟基磷灰石对污染土壤中镉的吸附-移除效果

    Adsorption and Removal of Cd from Contaminated Soil by Magnetic Nano-hydroxyapatite

    • 摘要: 为从污染土壤中吸附移除重金属镉(Cd),将共沉淀法合成的磁性纳米羟基磷灰石(nHAP@Fe3O4)分别按0、0.1%、0.5%、1.0%、3.0%比例添加至土壤中,在修复21、30、45 d时,磁分离nHAP@Fe3O4与土壤,考察nHAP@Fe3O4对土壤Cd的去除、材料的回收效果及修复后土壤理化性质的变化。结果表明,w(Cd)为2.510 mg·kg-1的重污染稻田土壤中添加1.0% nHAP@Fe3O4, 修复21 d时土壤Cd去除和材料回收效果最好,Cd平均去除率和材料回收率分别为16.45%和85.33%;nHAP@Fe3O4能明显降低土壤Cd的可交换态,促使其向较稳定的形态转化;经nHAP@Fe3O4修复后的土壤pH值升高,CEC有所降低,土壤颗粒间孔隙增大。利用磁性将nHAP@Fe3O4及其吸附的Cd从土壤中分离出来,以此实现对土壤Cd的吸附-移除。该方法对土壤理化性质影响较小,适宜修复重度污染程度的农田土壤。

       

      Abstract: In order to remove cadmium (Cd) from contaminated soil, magnetic nano hydroxyapatite (nHAP@Fe3O4) was synthesized by co-precipitation method under the soil water ratio of 1∶1 precursor. 0, 0.1%, 5%, 1.0% and 3.0% nHAP@Fe3O4 were then added to soil, respectively. After 21, 30 and 45 days of remediation, magnetic separation was used to separate nHAP@Fe3O4 from soil, and the removal rates of Cd in soil, the recovery effect of materials and the changes of soil physical and chemical properties after remediation were then investigated. The results show that the average Cd removal rate and the material (nHAP@Fe3O4) recovery rate of heavy polluted paddy soil (containing 2.510 mg·kg-1 of Cd) with the addition of 1% nHAP@Fe3O4 were 16.45% and 85.33%, respectively. The nHAP@Fe3O4 can significantly reduce the exchangeable and carbonate bound forms of soil Cd, and promote its transformation to a more stable form. After the remediation by nHAP@Fe3O4, the pH of the soil was increased, while the CEC decreased and the pore size between soil particles was increased. The removal of Cd from soil could be realized by using magnetic method to separate nHAP@Fe3O4 and adsorb Cd from the soil, which has little effect on soil physico-chemical properties. It is suitable for the remediation of severely polluted agicultural soil.

       

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