Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education)/Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering , Nankai University , Tianjin 300350 , China.
Guangzhou Key Laboratory of Environmental Catalysis and Pollution Control, Institute of Environmental Health and Pollution Control, School of Environmental Science and Engineering , Guangdong University of Technology , Guangzhou , 510006 , China.
Environ Sci Technol. 2019 Apr 2;53(7):3773-3781. doi: 10.1021/acs.est.8b05232. Epub 2019 Mar 21.
The interactions between nanoparticles and humic acid (HA) are critical to understanding the environmental risks and applications of nanoparticles. However, the interactions between HA fractions and graphene oxide (GO, a popular carbon nanosheet) at the molecular level remain largely unclear. Four HA fractions with molecular weights ranging from 4.6 to 23.8 kDa were separated, and the large HA fractions presented low oxygen contents and many aromatic structures. The binding constants of the large HA fractions on GO were 2.6- to 3551-fold higher than those of the small HA fractions, while the maximum adsorption capacities of the larger HA fractions onto GO were much higher. Atomic force microscopy (AFM) found that the small and large HA fractions were spread over the center and the edge of the GO nanosheets, respectively. Density functional theory (DFT) simulation and nuclear magnetic resonance spectroscopy confirmed the above phenomena (three adsorption patterns, "vs", "ps", and "pea") and revealed that HA bonded to the GO nanosheets mainly through van der Waals force and π-π interactions. The integrating analysis of binding affinity, AFM, and DFT provides new insights into the environmental behavior of GO and the applications of GO in pollutant removal under exposure from HA.
纳米颗粒与腐殖酸（HA）之间的相互作用对于理解纳米颗粒的环境风险和应用至关重要。然而，HA 分馏物与氧化石墨烯（GO，一种常见的碳纳米片）之间在分子水平上的相互作用在很大程度上仍不清楚。分离出分子量在 4.6 至 23.8 kDa 之间的 4 种 HA 分馏物，较大的 HA 分馏物含氧较低且具有许多芳香结构。大 HA 分馏物与 GO 的结合常数比小 HA 分馏物高 2.6 至 3551 倍，而较大的 HA 分馏物在 GO 上的最大吸附容量要高得多。原子力显微镜（AFM）发现小 HA 分馏物和大 HA 分馏物分别分布在 GO 纳米片的中心和边缘。密度泛函理论（DFT）模拟和核磁共振波谱学证实了上述现象（三种吸附模式，"vs"、"ps"和"pea"），并表明 HA 主要通过范德华力和 π-π 相互作用与 GO 纳米片结合。结合亲和力、AFM 和 DFT 的综合分析为 GO 的环境行为以及在 HA 暴露下用于去除污染物的 GO 的应用提供了新的见解。
