Pickering Aqueous Foam Stabilized by Rice Bran Wax Byproduct: A Sustainable and Multiscale Approach

Rice bran wax Pickering-stabilized aqueous foams were obtained using a one-pot, fast, energy-efficient, and scalable process and a two-compound only formula: rice bran wax (RBW) powder and water. A multiscale analysis was carried out to characterize the physical properties and stability of the foam with a concentration range from 5 to 12 wt %. The study then focused on the 12 wt % foam to investigate its microstructure and provide evidence of the Pickering effect in the foam stabilization. The foam exhibits a dense structure, with a firmness of 2 N and an apparent density close to 0.5 g/mL. Even though it was subjected to rapid drainage of excess water, its overall structure remained stable over several months. Moreover, the foam could be dried, and a dry foam was obtained from which RBW could be recovered. The feasibility of recycling dried RBW powder across multiple cycles to create new foams was studied. While material losses were observed during each cycle, it was demonstrated that formulating new foams from the recovered powder is possible. This research highlights promising opportunities for sustainable and eco-designed products and opens new perspectives in the development of environmentally friendly Pickering-stabilized aqueous foams while valorizing vegetal byproducts.