New insights into the impact of graphene oxide characteristics on foam stability: from bulk behavior to bubble dynamics

Foam stability is critical for various engineering applications. Despite this, foam generated from pure surfactant solutions is often highly unstable, limiting its practical effectiveness. In this study, we investigate the potential of graphene oxide (GO) as an aqueous foam stabilizer under highly saline conditions, using bulk- and bubble-scale experiments. Previous studies have shown that GO, at very low concentrations (~300 ppm), can negatively impact foam stability, highlighting the importance of surface modification to enhance its performance as a foam stabilizer. In contrast, our research offers a novel perspective by exploring the intrinsic characteristics of unmodified GO. Bulk-scale experiments were conducted using GO particles of different lateral sizes: GO ( ~ 20 μm), GO-son ( ~ 500 nm), and NGO ( ~ 20 nm), at concentrations ranging from 70 ppm to 300 ppm. Our results demonstrate that reducing the particle size of GO significantly improves foam stability by promoting the formation of a network of aggregates at the lamellae and Plateau borders, outperforming the foam produced with larger GO variants. The bulk-scale experiments were further complemented by bubble-scale observations, which revealed that NGO particles pack efficiently at the liquid-air interface, thereby strengthening the lamella structure and preventing Ostwald ripening. Moreover, our results show that the NGO maintains enhanced foam stability even in the presence of decane. Overall, we demonstrate that unmodified GO can effectively stabilize foam at low concentrations, eliminating the need for multi-step chemical modification, which often increases costs and raises environmental concerns. • Experiments were conducted with different sizes of GO particles at low concentrations. • Reducing the particle size of GO enhances foam stability without surface modification. • Under saline conditions, NGO reinforces foam via formation of aggregates. • NGO can stabilize foam in the presence of hydrocarbons.