Department of Civil Engineering, McGill University , Montreal, Quebec, Canada.
Environment and Climate Change Canada , Gatineau, Quebec, Canada.
Environ Sci Technol. 2016 Dec 20;50(24):13318-13327. doi: 10.1021/acs.est.6b03957. Epub 2016 Dec 6.
Ag nanoparticles (nAg) are used in various consumer products and a significant fraction is eventually discharged with municipal wastewater (WW). In this study we assessed the release of Ag from polyvinylpyrrolidone (PVP)- and citrate-coated 80 nm nAg in aerobic WW effluent and mixed liquor and the related changes in nAg size, using single particle ICP-MS (spICP-MS). The concentration of dissolved (nonparticulate) Ag in WW effluent was 0.89 ± 0.05 ppb at 168 h and was 71% lower than in deionized (DI) water, in batch reactors spiked with 5 × 10 PVP-nAg particles/mL (10 μg/L), an environmentally relevant concentration. Dissolved Ag in WW was partly reformed into ∼22 nm nAgS by inorganic sulfides and organosulfur dissolved organic carbon (DOC) after 120 h, whereas the parent nAg mean diameter decreased to 65.89 ± 0.9 nm. Reformation of nAgS from Ag also occurred in cysteine solutions but not in DI water, or humic and fulvic acid solutions. Dissolution experiments with nAg in WW mixed liquor showed qualitatively similar dissolution trends. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS) analyses indicated binding of thiol- and amine-containing DOC as well as inorganic sulfides with nAg. Those WW components, as well as limited dissolved oxygen, decreased dissolution in WW.
纳米银颗粒（nAg）被广泛应用于各种消费产品中，其中相当一部分最终会随着城市污水（WW）排放。在本研究中，我们使用单颗粒电感耦合等离子体质谱（spICP-MS）评估了在有氧 WW 废水和混合液中，聚维酮（PVP）和柠檬酸盐包覆的 80nm nAg 的银释放情况，以及 nAg 粒径的相关变化。在 168 小时时，WW 废水中溶解（非颗粒）银的浓度为 0.89 ± 0.05 ppb，比用去离子（DI）水在批式反应器中连续加入 5×10 PVP-nAg 颗粒/mL（10μg/L）时低 71%，这是一个与环境相关的浓度。120 小时后，WW 中的溶解银部分被无机硫化物和有机硫溶解的有机碳（DOC）还原为~22nm 的 nAgS，而原始 nAg 的平均粒径减小至 65.89 ± 0.9nm。在半胱氨酸溶液中，nAgS 也可以从银中重新形成，但在 DI 水、腐殖酸和富里酸溶液中则不会。在 WW 混合液中进行的 nAg 溶解实验也显示出了类似的溶解趋势。飞行时间二次离子质谱（ToF-SIMS）和 X 射线光电子能谱（XPS）分析表明，DOC 中的巯基和胺基以及无机硫化物与 nAg 发生了结合。这些 WW 成分以及有限的溶解氧，降低了 WW 中的溶解速度。
