Interaction between Al 2 O 3 and different sizes of GO in aqueous environment.

Although the aggregation of graphene oxide (GO) has been widely researched, the influence of the GO size on the homoaggregation behavior and its interaction with environmental media are still unexplored. In this work, critical coagulation concentration (CCC) values for GO with different sizes, from micro to nanosheet, were measured with NaCl and CaCl2 electrolytes, and the results indicated that GO with the largest size presented the smallest CCC value. Aluminum oxide (Al2 O3 ) was selected as a natural solid particle representative to mimic the interaction between GO and environmental media. Batch experiments were conducted in solution with different pH and ionic strength. Results indicated that the attachment capacity of large GO onto Al2 O3 particles was greater than that of small GO. The experimental data were well fitted with Freundlich model. The electrostatic attraction and hydrogen-bonding interaction dominated the interaction process between GO and Al2 O3 . These findings are important for better understanding in the environmental fate and transport of GO.