Effects Of Oxygen Ultrafine Bubble Injection On The Storage Stability And Physicochemical Properties Of B35 Biodiesel

Abstract

The implementation of B35 biodiesel has significantly contributed to renewable energy utilization in the transportation sector. However, the higher fatty acid methyl ester (FAME) content in B35 biodiesel increases its susceptibility to physicochemical degradation during storage, making storage stability a critical concern. Oxygen ultrafine bubble (UFB) technology has recently been reported to improve diesel combustion performance, yet its influence on the storage stability of biodiesel has not been comprehensively investigated. This study evaluated the effects of oxygen UFB injection on the physicochemical properties and storage stability of B35 biodiesel during seven weeks of storage. Normal B35 biodiesel (CN48) and oxygen UFB-treated B35 biodiesel were comparatively evaluated based on kinematic viscosity, density, water content, total acid number, and oxidation stability at weekly intervals. The experimental results demonstrated that oxygen UFB treatment increased viscosity and density while reducing water content and oxidation stability, whereas the total acid number remained relatively unaffected immediately after treatment. During storage, both untreated and UFB-treated fuels exhibited gradual increases in viscosity, density, water content, and acid number, accompanied by a decline in oxidation stability. Nevertheless, all measured parameters remained within the quality limits specified by the Indonesian Directorate General of Oil and Gas Standard No. 170.K/HK.02/DJM/2023 after seven weeks of storage. These findings indicate that although oxygen ultrafine bubble injection modifies several physicochemical characteristics of B35 biodiesel, it does not compromise its storage quality within the investigated storage period. The results provide important insights into the feasibility of applying oxygen ultrafine bubble technology to biodiesel fuels while maintaining compliance with national fuel quality standards.