Impact of Al₂O₃ on the Aggregation and Deposition of Graphene Oxide

To assess the environmental behavior and impact of graphene oxide (GO) on living organisms more accurately, the aggregation of GO and its deposition on Al₂O₃ particles were systematically investigated using batch experiments across a wide range of solution chemistries. The results indicated that the aggregation of GO and its deposition on Al₂O₃ depended on the solution pH and the types and concentrations of electrolytes. MgCl₂ and CaCl₂ destabilized GO because of their effective charge screening and neutralization, and the presence of NaH₂PO₄ and poly­(acrylic acid) (PAA) improved the stability of GO with the increase in pH values as a result of electrostatic interactions and steric repulsion. Specifically, the dissolution of Al₂O₃ contributed to GO aggregation at relatively low pH or high pH values. Results from this study provide critical information for predicting the fate of GO in aquatic-terrestrial transition zones, where aluminum (hydro)­oxides are present