复合纳米材料对土壤重金属离子吸持固化的模拟研究

土壤中过量重金属离子可通过食物链和地表水系统危害人群健康。通过土柱淋溶模拟实验,研究了SiO2-Al2O3-Fe2O3等复合纳米材料对土壤溶液中Cu2+、Cd2+、Pb2+、Zn2+和Ni2+的吸持与固化特征。分别向重金属含量4倍于土壤二级标准(GB15618-1995)的土壤中添加0%、4%、6%和10%的复合纳米材料,分析不同深度土壤渗滤液以及土柱上栽培植物不同部位中重金属的含量。结果表明,碱性壤质土壤中重金属向下的迁移量很少;在含4%复合纳米材料土柱中,其吸持固化土壤溶液中63%的Cu、79%的Cd、68%的Pb、89%的Zn和76%的Ni;在含6%复合纳米材料土柱中,其吸持固化土壤溶液中82%的Cu、92%的Cd、76%的Pb、91%的Zn和88%的Ni;再增加土柱中复合纳米材料的含量,其吸持固化效果并不再显著增加。

Simulation study on sorption and fixation of composite nanomaterial to heavy metal ions in soil

People may face healthy threats due to the excess of heavy metals ion in soil transferred by food chain and surface water system. Through soil column leaching methods, we studied the sorption and fixation effects of composite nanomaterials (SiO₂-Al₂O₃-Fe₂O₃, etc) upon Cu²⁺, Cd²⁺, Pb²⁺, Zn²⁺, Ni²⁺ in soil solution. Different nano-composites (0%, 4%, 6%, 10% of soil mass) were added to the soil with the heavy metals concentrations of 4 times of Grade 2 levels in Soil Quality Standard (GB15618-1995), and then, the heavy metals concentrations in soil solution at different depths and in different organs of the plants cultivated on the soil column were analyzed. Results showed that less amount of heavy metals in alkaline loamy soil moving downward, while the soil column with 4% nano-composites absorbed 63% content of Cu, 79% of Cd, 68% of Pb, 89% of Zn and 76% of Ni in soil solution, and the soil column with 6% nano-composites absorbed 82% content of Cu, 92% of Cd, 76% of Pb, 91% of Zn and 88% of Ni in soil solution. Experimental soil column with more than 6% nano-composites in soil showed no more significant ability of absorbing heavy metals.