摘要
近些年来,环境研究者对纳米颗粒的迁移性进行了部分研究,但是对环境稳定性低、反应活性高的金属氧化物工程纳米颗粒在多孔介质中的运移沉积行为的系统探讨还很不足,尤其是对其在有机质(NOM)存在条件下迁移行为的了解非常有限。本研究选用四氧化三铁磁纳米颗粒(MENPs)作为研究对象,采用填充柱淋溶实验法,对其在饱和多孔介质中的迁移持留行为展开探讨,其目的是考察几种主要介质环境物理因素对其在天然有机质存在条件下的纵向淋溶过程及其在介质中持留量的影响作用。结果显示,不利吸附条件下的MENPs集聚体在多孔介质中的吸附持留及迁移性能取决于多种合力的作用效果。其中,孔隙水流速增大时,MENPs在多孔介质中的迁移性增强,持留性减弱,持留MENPs在介质中的逐层分布随孔隙水流速改变而变化;而且,MENPs在多孔介质中的迁移持留性与介质颗粒的表面物理性质也有关,天然有机质的存在一定程度上可以改善石英砂表面的异质性。另外,介质颗粒粒径大小也是影响MENP-介质间持留机制的重要因子。当多孔介质颗粒粒径大小改变时,MENPs穿透曲线及持留分布曲线随之变化明显,MENPs的吸附沉积机制也相应有所不同。
In recent years,more and more researches on the mobility of nanoparticles（NPs）in porous media have been done.However,for the metal oxide NPs which are of low environmental stability and high interactivity,the understanding of their transport and deposition behav-iors in porous media are still far from enough,especially when in the presence of NOM.In this study,we conducted a series of column experi-ments and systematically examined the effects of the physical factors on the transport and retention behaviors of magnetite（Fe3O4）engineered nanoparticles（MENPs）,selected as a model for metal oxide NPs,during leaching through the saturated porous media.The results showed that in unfavorable deposition conditions（with constant chemical factors）the mobility or deposition of MENPs substantially depended on the ef-fects of multiple forces which were induced by several physical factors.With the increase of pore velocity,the mobility of MENPs was en-hanced and the retention onto porous media was decreased obviously.Accordingly,the spatial retention profiles in porous media were found varied greatly at different pore velocities.Besides,it was also observed that the physical properties（the surface roughness and size of the grain）of porous media（collector）influenced the mobility and deposition of MENPs dramatically.The presence of NOM could reduce the surface heterogeneity of quartz sands.With the different diameters of collector grain,the BTCs and retention profiles of MENPs changed obviously and the mechanisms of retention were also found different.
出处
《农业环境科学学报》
CAS
CSCD
北大核心
2010年第10期2017-2024,共8页
Journal of Agro-Environment Science
基金
国家自然科学基金(40525003)
