Green Synthesis of Silica Nanoparticles from Sugarcane Bagasse Ash for Stable Pickering Oil-in-Water Emulsions

The present study explores novel alternatives for the exploitation of sugarcane bagasse ash by obtaining and modifying SiO₂ nanoparticles through a green synthesis method. The hydrophilic nature of the nanoparticles was modified using oleic acid. The nanoparticles were characterized using FTIR, FESEM, and DLS, and their performance in the stabilization of Pickering emulsions was also studied. FESEM micrographs of the nanoparticles revealed an irregular and agglomerated structure. EDS confirmed that their main components are oxygen and silicon, and ATR-FTIR spectra demonstrated that oleic acid effectively modified the nanoparticles. Subsequently, O/W Pickering emulsions were fabricated by combining rotor–stator homogenization and probe ultra-sonication, using dodecane and liquid paraffin as model oil phases and SiO₂ NPs as stabilizers. Static light scattering measurements showed that the emulsions exhibited polydispersity, while photographic monitoring confirmed that their physical stability was affected by the concentrations of oleic acid and nanoparticles: concentrations of up to 20.0 wt% and 1.0 wt%, respectively, produced emulsions that remained stable for 7 to 15 days. This study identifies the behavior and challenges associated with novel pathways for the valorization of sugarcane bagasse ash. The stabilization of Pickering emulsions using the obtained SiO₂ NPs highlights their potential in pharmaceutical, cosmetic, and food applications.