U.S. Environmental Protection Agency, Office of Research and Development, Cincinnati, OH, USA.
Environ Sci Technol. 2010 Feb 15;44(4):1307-12. doi: 10.1021/es9032265.
Assessments of the environmental fate and mobility of nanoparticles must consider the behavior of nanoparticles in relevant environmental systems that may result in speciation changes over time. Environmental conditions may act on nanoparticles to change their size, shape, and surface chemistry. Changing these basic characteristics of nanoparticles may result in a final reaction product that is significantly different than the initial nanomaterial. As such, basing long-term risk and toxicity on the initial properties of a nanomaterial may lead to erroneous conclusions if nanoparticles change upon release to the environment. The influence of aging on the speciation and chemical stability of silver and zinc oxide nanoparticles in kaolin suspensions was examined in batch reactors for up to 18 months. Silver nanoparticles remained unchanged in sodium nitrate suspensions; however, silver chloride was identified with the metallic silver nanoparticles in sodium chloride suspensions and may be attributed to an in situ silver chloride surface coating. Zinc oxide nanoparticles were rapidly converted via destabilization/dissolution mechanisms to Zn(2+) inner-sphere sorption complexes within 1 day of reaction and these sorption complexes were maintained through the 12 month aging processes. Chemical and physical alteration of nanomaterials in the environment must be examined to understand fate, mobility, and toxicology.
评估纳米粒子的环境归宿和迁移性必须考虑到纳米粒子在相关环境系统中的行为，这些行为可能导致纳米粒子随时间发生形态变化。环境条件可能会作用于纳米粒子，改变它们的大小、形状和表面化学性质。这些纳米粒子的基本特性的改变可能会导致最终的反应产物与初始纳米材料有显著的不同。因此，如果纳米粒子在释放到环境中后发生变化，那么基于纳米材料初始特性的长期风险和毒性评估可能会得出错误的结论。在间歇反应器中，研究了长达 18 个月的高岭土悬浮液中银和氧化锌纳米粒子的形态和化学稳定性的老化影响。在硝酸钠悬浮液中，银纳米粒子保持不变；然而，在氯化钠悬浮液中发现了与金属银纳米粒子共存的氯化银，这可能归因于原位氯化银表面涂层。氧化锌纳米粒子在反应后 1 天内通过失稳/溶解机制迅速转化为 Zn(2+)内球吸附络合物，并通过 12 个月的老化过程保持这些吸附络合物。必须检查环境中纳米材料的化学和物理变化，以了解其归宿、迁移性和毒理学。
