Laboratory of Analytical Chemistry and Applied Ecochemistry, Department of Applied Analytical and Physical Chemistry, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, Ghent, Belgium.
Laboratory of Analytical Chemistry and Applied Ecochemistry, Department of Applied Analytical and Physical Chemistry, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, Ghent, Belgium.
Environ Res. 2015 Oct;142:207-14. doi: 10.1016/j.envres.2015.06.028. Epub 2015 Jul 10.
The stability of engineered nanoparticles (ENPs) in complex aqueous matrices is a key determinant of their fate and potential toxicity towards the aquatic environment and human health. Metal oxide nanoparticles, such as CeO2 ENPs, are increasingly being incorporated into a wide range of industrial and commercial applications, which will undoubtedly result in their (unintentional) release into the environment. Hereby, the behaviour and fate of CeO2 ENPs could potentially serve as model for other nanoparticles that possess similar characteristics. The present study examined the stability and settling of CeO2 ENPs (7.3±1.4 nm) as well as Ce(3+) ions in 10 distinct natural surface waters during 7d, under stagnant and isothermal experimental conditions. Natural water samples were collected throughout Flanders (Belgium) and were thoroughly characterized. For the majority of the surface waters, a substantial depletion (>95%) of the initially added CeO2 ENPs was observed just below the liquid surface of the water samples after 7d. In all cases, the reduction was considerably higher for CeO2 ENPs than for Ce(3+) ions (<68%). A first-order kinetics model was able to describe the observed time-dependant removal of both CeO2 ENPs (R(2)≥0.998) and Ce(3+) ions (R(2)≥0.812) from the water column, at least in case notable sedimentation occurred over time. Solution-pH appeared to be a prime parameter governing nanoparticle colloidal stability. Moreover, the suspended solids (TSS) content also seemed to be an important factor affecting the settling rate and residual fraction of CeO2 ENPs as well as Ce(3+) ions in natural surface waters. Correlation results also suggest potential association and co-precipitation of CeO2 ENPs with aluminium- and iron-containing natural colloidal material. The CeO2 ENPs remained stable in dispersion in surface water characterized by a low pH, ionic strength (IS), and TSS content, indicating the eventual stability and settling behaviour of the nanoparticles was likely determined by a combination of physicochemical parameters. Finally, ionic release from the nanoparticle surface was also examined and appeared to be negligible in all of the tested natural waters.
工程纳米粒子（ENPs）在复杂水介质中的稳定性是决定其命运和对水生环境及人类健康潜在毒性的关键因素。金属氧化物纳米粒子，如 CeO2 ENPs，越来越多地被纳入各种工业和商业应用中，这无疑将导致它们（无意）释放到环境中。因此，CeO2 ENPs 的行为和命运可能可以作为其他具有相似特性的纳米粒子的模型。本研究考察了 CeO2 ENPs（7.3±1.4nm）以及 Ce（3+）离子在 7d 内，在静止和等温实验条件下，在 10 种不同天然地表水中的稳定性和沉降情况。天然水样采集自整个比利时的弗兰德斯地区，并进行了全面的特性描述。对于大多数地表水，在 7d 后，水样的液体表面下观察到最初添加的 CeO2 ENPs 大量耗尽（>95%）。在所有情况下，CeO2 ENPs 的还原量都明显高于 Ce（3+）离子（<68%）。一级动力学模型能够描述观察到的 CeO2 ENPs（R（2）≥0.998）和 Ce（3+）离子（R（2）≥0.812）在水柱中随时间的去除情况，至少在长时间内发生明显沉降的情况下是这样。溶液 pH 值似乎是控制纳米颗粒胶体稳定性的主要参数。此外，悬浮固体（TSS）含量似乎也是影响 CeO2 ENPs 以及 Ce（3+）离子在天然地表水中沉降速率和残留分数的重要因素。相关结果还表明，CeO2 ENPs 可能与含铝和铁的天然胶体物质发生潜在的缔合和共沉淀。在 pH 值、离子强度（IS）和 TSS 含量低的地表水表面，CeO2 ENPs 保持稳定分散，表明纳米颗粒的最终稳定性和沉降行为可能由一系列物理化学参数决定。最后，还检查了从纳米颗粒表面释放的离子，在所有测试的天然水中似乎都可以忽略不计。
