Hazard Evaluation of Nitrocellulose Synthesized from Okara (soy bean-curd refuse) as a Raw Material

Abstract. Nitrocellulose (NC), used in gunpowder and paints, is synthesized by nitrating cellulose through a reaction with mixed acids (sulfuric acid and nitric acid). While cotton linter and wood chips are commonly used as cellulose-containing raw materials, recent studies have explored NC synthesis techniques using previously untapped materials such as nata de coco. In this study, nitrocellulose was successfully synthesized using 'Okara' (soybean-curd refuse), a waste byproduct containing 42% insoluble dietary fiber, generated during the production of 'Tofu,' a traditional Japanese food. The raw Okara was pretreated to remove impurities using an alkaline solution, and followed by a nitration reaction. Finally, the product was collected after repeated hot water washing. Structural analysis of the resulting pale yellow powder using Fourier-transform infrared spectroscopy (FTIR) revealed three peaks derived from nitrate groups, suggesting the formation of NC. Thermal analysis and friction sensitivity tests were conducted on the obtained NC, and the results were compared with those of conventional NC used as a propellant material. DSC results revealed that the exothermic onset temperature of Okara-derived NC was lower than that of conventional NC, but the peak shape mostly corresponded to that of conventional NC.