Department of Civil and Environmental Engineering, Duke University , Durham, North Carolina 27708, United States.
Center for the Environmental Implications of NanoTechnology (CEINT), Duke University , Durham, North Carolina 27708, United States.
Environ Sci Technol. 2017 Nov 21;51(22):13288-13294. doi: 10.1021/acs.est.7b04612. Epub 2017 Oct 31.
As process-based environmental fate and transport models for engineered nanoparticles are developed, there is a need for relevant and reliable measures of nanoparticle behavior. The affinity of nanoparticles for various surfaces (α) is one such measure. Measurements of the affinity of nanoparticles obtained by flowing particles through a porous medium are constrained by the types of materials or exposure scenarios that can be configured into such column studies. Utilizing glass beads and kaolinite as model collector surfaces, we evaluate a previously developed mixing method for measuring nanoparticle attachment to environmental surfaces, and validate this method with an equivalent static column system over a range of organic matter concentrations and ionic strengths. We found that, while both impacted heteroaggregation rates in a predictable manner when varied individually, neither dominated when both parameters were varied. The theory behind observed nanoparticle heteroaggregation rates (αβB) to background particles in mixed systems is also experimentally validated, demonstrating both collision frequency (β) and background particle concentration (B) to be independent for use in fate modeling. We further examined the effects of collector particle composition (kaolinite vs glass beads) and nanoparticle surface chemistry (PVP, citrate, or humic acid) on α, and found a strong dependence on both.
随着基于过程的工程纳米颗粒环境归趋和迁移模型的发展，人们需要对纳米颗粒的行为进行相关且可靠的测量。纳米颗粒对各种表面的亲和力（α）就是这样一种测量方法。通过让颗粒在多孔介质中流动来测量纳米颗粒亲和力的方法受到可以配置成这种柱状研究的材料类型或暴露场景的限制。本文利用玻璃珠和高岭土作为模型收集表面，评估了一种先前开发的用于测量纳米颗粒与环境表面附着的混合方法，并在一系列有机物浓度和离子强度范围内，通过等效静态柱状系统对该方法进行了验证。我们发现，虽然当这两个参数单独变化时，它们都可以以可预测的方式影响非均相聚集速率，但当两个参数都变化时，它们都没有占主导地位。混合体系中背景颗粒上观察到的纳米颗粒非均相聚集速率（αβB）背后的理论也通过实验得到了验证，这表明碰撞频率（β）和背景颗粒浓度（B）在用于归趋建模时是相互独立的。我们进一步研究了收集颗粒成分（高岭土与玻璃珠）和纳米颗粒表面化学性质（PVP、柠檬酸或腐殖酸）对α的影响，发现这两者都有很强的依赖性。
