Isopropyl myristate oil-based pickering emulsions stabilized by N-[3-(trimethoxysilyl)propyl]ethylenediamine-modified biosilica nanoparticles from rice husk.

Rice husk is an agricultural waste generated during rice milling and very rich in biosilica. Extraction, and modification of biosilica from rice husk were performed, and the isopropyl myristate oil-based emulsions stabilized by the modified biosilica nanoparticles were also studied. The native biosilica was modified by N-[3-(trimethoxysilyl)propyl] ethylenediamine. Characterization by energy-dispersive x-ray spectroscope showed that native biosilica contains oxygen (25.3%), silica (66.2%), and sodium (8.5%), and modified biosilica compositions are oxygen (31.6%), silica (39.4%), carbon (25.5%), and sodium (1.2%). X-ray diffraction analysis revealed that crystallite sizes of native biosilica and modified biosilica are 2.05 nm and 2.03 nm, respectively. The change in surface morphology as revealed by scanning electron microscopy confirmed that modification occurred. The emulsions stabilized by the modified biosilica nanoparticles were stable, while the emulsion stabilized by the native biosilica was not stable. The influence of pH on the stability and physical appearance of the emulsions was not significant. However, the water–oil ratio has significant influence on the stability of the emulsions and the optimal oil:water ratio was 80:20. The utilization of rice husk ash for the production of biosilica nanoparticles would reduce environmental pollution and health challenges associated with fly ash. The results from this study showed that modified biosilica nanoparticles is a good emulsifier and promising material in cosmetics and pharmaceutical applications. [ABSTRACT FROM AUTHOR]