College of Environmental Science and Engineering, Ministry of Education Key Laboratory of Pollution Processes and Environmental Criteria, Tianjin Key Laboratory of Environmental Remediation and Pollution Control, Nankai University, Tianjin, China.
Environ Toxicol Chem. 2014 May;33(5):998-1004. doi: 10.1002/etc.2525. Epub 2014 Mar 12.
The authors conducted column experiments and a modeling study to understand the effects of several environmental factors on the aggregation and transport of graphene oxide nanoparticles (GONPs) in saturated quartz sand. The GONPs were negatively charged and stable under the test conditions (0-50 mM NaCl; pH 4.8-9.0), and the Derjaguin-Landau-Verwey-Overbeek (DLVO) calculation indicated that deposition of GONPs was under unfavorable attachment conditions. The GONPs exhibited high mobility even at an ionic strength of 25 mM NaCl. The transport of GONPs was insensitive to the changes of pH (from 5.1 to 9.0), but the presence of 10 mg/L Suwannee River humic acid (SRHA) considerably enhanced transport at high ionic strength (35 mM NaCl), likely via enhanced steric repulsion and significantly inhibited stacking of GO flakes. Varying flow velocity also enhanced transport at high ionic strength. In general, GONPs exhibit greater mobility compared with other carbon nanoparticles because the aggregation and transport of GONPs are more resilient to changes in solution chemistry and hydrodynamic forces that favor aggregation and deposition of nanoparticles. A 2-site transport model incorporating both the blocking-affected attachment process and straining effects can effectively model the transport of GONPs. The high mobility of GONPs should be given full consideration in assessing their environmental risks.
作者进行了柱实验和建模研究，以了解几种环境因素对饱和石英砂中氧化石墨烯纳米颗粒（GONPs）聚集和迁移的影响。在测试条件下（0-50 mM NaCl；pH 4.8-9.0），GONPs 带负电荷且稳定，德加古林-兰德维厄-奥弗贝克（DLVO）计算表明 GONPs 的沉积处于不利附着条件下。即使在 25 mM NaCl 的离子强度下，GONPs 也表现出很高的迁移率。GONPs 的迁移对 pH 的变化（从 5.1 到 9.0）不敏感，但存在 10 mg/L 苏万尼河腐殖酸（SRHA）时，在高离子强度（35 mM NaCl）下会显著增强迁移，这可能是由于增强了空间排斥作用，并显著抑制了 GO 薄片的堆积。改变流速也会在高离子强度下增强迁移。总的来说，与其他碳纳米粒子相比，GONPs 表现出更大的迁移性，因为 GONPs 的聚集和迁移对溶液化学和有利于纳米颗粒聚集和沉积的流体动力变化的抵抗力更强。一个包含阻塞影响附着过程和应变效应的双位置传输模型可以有效地模拟 GONPs 的传输。在评估其环境风险时，应充分考虑 GONPs 的高迁移性。
