天然水体中多壁纳米碳管对纳米氧化锌颗粒团聚与沉降行为的影响

研究了淡水湖泊水体中氧化多壁纳米碳管(Oxidized-multiwalled carbon nanotubes,o-MWCNTs)对纳米氧化锌(ZnO nanoparticles,nZnO)颗粒团聚与沉降行为的影响,探讨了天然胶体及o-MWCNTs的浓度对nZnO颗粒团聚粒径、团聚速率及沉降行为的作用.结果表明,nZnO在天然水体中会发生明显沉降,相比去除天然胶体的天然水而言,天然胶体的存在显著减少了nZnO的沉降.这主要归因于nZnO-天然胶体颗粒间的作用能垒高于nZnO-nZnO颗粒间的作用能垒,使得天然胶体的存在降低了nZnO-nZnO之间的颗粒碰撞效率,从而促进nZnO悬浮.o-MWCNTs对nZnO在天然水体中沉降行为的影响与天然胶体密切相关.相比于nZnO的单独沉降,在不过膜天然水中(含天然胶体),低浓度o-MWCNTs的存在增加了颗粒间的团聚速率,从而促进nZnO的沉降,而高浓度o-MWCNTs降低了颗粒间的团聚速率和团聚体粒径,从而降低了nZnO的沉降.而在过膜天然水中(不含天然胶体),o-MWCNTs的存在显著降低了颗粒间的团聚粒径和团聚速率,从而降低了nZnO的沉降,且o-MWCNTs的浓度越高,对nZnO悬浮稳定性的促进作用越明显.

Effect of oxidized-multiwalled carbon nanotubes on the aggregation and sedimentation behaviors of ZnO nanoparticles in natural water

This study investigated the influence of oxidized-multiwalled carbon nanotubes(o-MWCNTs) on the aggregation and sedimentation behaviors of ZnO nanoparticles in lake water, and particularly explored the effect of natural colloids and the concentration of o-MWCNTs on the size, rates of nZnO aggregation and its sedimentation behavior. The results show that the nZnO settled obviously in the natural water and the presence of natural colloidal significantly reduced the sedimentation of nZnO comparing to that in the filtered natural water without natural colloid.The interaction energy barrier between nZnO and natural colloids was higher than that between nZnO particles. The existence of natural colloidal particles could reduce the collision efficiency between nZnO particles, thus promoting nZnO suspension. The influences of natural colloids and o-MWCNTs on nZnO sedimentation behavior in natural water are closely related. In the natural water with colloids, compared to the nZnO individual sedimentation process, low concentration of o-MWCNTs increased the aggregation rate between the particles, so as to promote the sedimentation of nZnO. While high concentration of o-MWCNTs decreased aggregation rate and size between the particles, which reduced the nZnO sedimentation. In the filtered natural water, the addition of o-MWCNTs significantly reduced the aggregation rate and size between the particles, which reduced the nZnO sedimentation. The higher the o-MWCNTs concentration, the more significant stalbe of nZnO in suspension.