纳米Ag在四种不同性质土壤上的吸附行为研究

纳米Ag的大量生产和使用增加了其进入土壤环境的风险, 其在土壤中的环境行为受纳米Ag胶体稳定性和土壤理化性质的影响。为探究纳米Ag颗粒在土壤上的吸附行为, 选取四种不同理化性质的土壤, 考察了土壤pH、有机质和二价阳离子Ca²⁺对纳米Ag在土壤上吸附的影响。结果表明, 纳米Ag在酸性土壤的吸附量高于中性土壤, 当土壤酸碱性相似时土壤有机质含量越高纳米Ag在其表面的吸附量越高, 纳米Ag在四种土壤上的吸附等温线都能较好地利用Freundlich方程进行拟合;Ca²⁺的存在均增加了纳米Ag在四种土壤上的吸附量, Ca²⁺浓度在0.1~10 mmol·L^-1范围内, 纳米Ag在中性土壤上的吸附量随Ca²⁺浓度的增加而增加, 而在酸性土壤上则随着Ca²⁺浓度的增加, 出现先增加后减小的趋势。这一结果有助于了解纳米银在不同性质土壤上的吸附行为, 为评价纳米Ag在环境中的毒性和生态风险提供了有用信息。

Sorption of Silver Nanoparticles on Four Soils with Different Characteristics

Large amount of silver nanoparticles(AgNPs) are being used in a wide range of aspects, which exhibited great risk to soil environment. The environmental fates of AgNPs in soil are markedly affected by AgNP stability and soil physicochemical properties. In this study,isothermal sorption of AgNPs on four types of soils with different physicochemical properties was investigated in the presence and the absence of Ca²⁺. The sorption isotherms of AgNPs on soils were well described with Freundlich isotherm equation. Soil pH and organic matter significantly affected the sorption of AgNPs by soils. The sorption amount of AgNPs on the acid soils was higher than that on the neutral soils. At the same soil pH,soil organic matter increased the AgNPs sorption capacity. The presence of Ca²⁺ generally increased the sorption capacity of AgNPs on these soils, but such effect showed slight difference between neutral and acid soils. In neutral soil, AgNPs sorption capacity increased with increasing Ca²⁺ concentrations from 0.1 mmol·L^-1 to 10 mmol·L^-1, whereas in acidic soil the sorption capacity showed "first increase and then decrease" over Ca concentrations. These results would be beneficial for environmental risk assessment of AgNPs.