New insights into the interaction between nanocolloid of graphene oxide and dissolved organic matter: Spectroscopic
Ang Liu1, Tuantuan Fan2, Weibo Zhang3
1State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 10012, China; College of Geo-exploration Science and Technology, Jilin University, Changchun 130026, China.
Abstract:
Graphene oxide (GO), due to its exceptional physicochemical properties, is widely used in industrial and agricultural fields and can exist as nanocolloid of GO (nGO) in aquatic environments. Dissolved organic matter (DOM), a major component of natural organic matter, significantly influences the environmental fate of nGO. However, their interaction mechanisms remain unclear. In this study, the interactions between DOM and nGO were systematically investigated under different DOM concentrations, pH values, and temperatures using excitation-emission matrix fluorescence combined with parallel factor analysis and modified Ryan-Weber quenching titration (3D-EEM-PARAFAC-QT), along with density functional theory (DFT) calculations. The Stern-Volmer model and fluorescence lifetime analysis that the quenching followed a static mechanism, suggesting the formation of stable DOM-nGO complexes. Binding constants (log K) between Elliott soil humic acid (ESHA) / Pahokee peat fulvic acid (PPFA) and nGO were estimated using a modified Ryan-Weber model and were influenced by DOM concentration and pH. Combined with DFT and Van't Hoff analysis, π-π stacking and hydrogen bonding (with bond lengths of ∼ 1.644-2.049 Å) and were identified as the dominant forces. These findings enhance the understanding of DOM-nGO interactions in aquatic systems and provide valuable insights into the environmental fate and potential ecological risks of nGO.
