State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University , Beijing 100875, People's Republic of China.
Environ Sci Technol. 2014 May 6;48(9):4946-53. doi: 10.1021/es500596a. Epub 2014 Apr 8.
The impact of perfluorocarboxylic acids (PFCAs) with carbon chain length C2 to C8 on the dissolution, aggregation, reactive oxygen species (ROS) generation, and toxicity of citrate-coated AgNPs was investigated under UV irradiation. The presence of PFCAs decreased dissolution, aggregation, ROS generation, and toxicity of AgNPs because the negatively charged PFCAs sorbed on AgNP surface enhanced their stability. Both dissolution and aggregation rate of AgNPs decreased with chain length of PFCAs under UV irradiation, primarily because PFCAs with longer chain length sorbed on AgNP surface could form thicker coatings. The dissolution of AgNPs followed pseudo-first-order kinetics, and the rate constant decreased from 0.58 h(-1) with C2 to 0.30 h(-1) with C8. The hydrodynamic diameters of AgNPs linearly increased under UV irradiation with aggregation rates ranged from 72.1 to 143.5 nm/h. O2(•-) generation was observed in AgNP suspension with quantum yield of 0.12%, but was completely suppressed by PFCAs because they inhibited the interaction between photoelectrons and O2. A linear correlation was established between dissolved Ag(+) and bacterial survival rates of AgNPs with and without PFCAs under UV irradiation. This study highlights the necessity of considering coexisting organic contaminants when investigating the environmental behaviors of AgNPs.
研究了碳链长为 C2 至 C8 的全氟羧酸（PFCAs）对柠檬酸包覆的 AgNPs 在紫外光照射下的溶解、聚集、活性氧物种（ROS）生成和毒性的影响。由于带负电荷的 PFCAs 吸附在 AgNP 表面上，增强了它们的稳定性，因此 PFCAs 的存在降低了 AgNPs 的溶解、聚集、ROS 生成和毒性。在紫外光照射下，AgNPs 的溶解和聚集速率均随 PFCAs 链长的增加而降低，这主要是因为长链 PFCAs 吸附在 AgNP 表面上可以形成更厚的涂层。AgNPs 的溶解遵循准一级动力学，速率常数从 C2 的 0.58 h(-1)降低到 C8 的 0.30 h(-1)。在紫外光照射下，AgNPs 的水动力直径随聚集速率线性增加，范围从 72.1nm/h 到 143.5nm/h。在 AgNP 悬浮液中观察到 O2(•-)的生成，量子产率为 0.12%，但被 PFCAs 完全抑制，因为它们抑制了光电子和 O2 之间的相互作用。在紫外光照射下，有和没有 PFCAs 时 AgNPs 的溶解 Ag(+)和细菌存活率之间建立了线性相关性。本研究强调了在研究 AgNPs 的环境行为时，必须考虑共存的有机污染物。
