Influence of minor components on precipitate formation and filterability of palm oil biodiesel

• Cold soak filtration time is only affected by free steryl glucosides.
• Increasing free steryl glucosides increases precipitation at low levels of moisture.
• In contrast, when monoglycerides increases, the precipitate content decreases.
• Interaction with moisture exacerbates precipitation.
• Models to predict cold soak filtration time and precipitate content are provided.

Precipitate formation has become an issue of concern for biodiesel producers in the last few years. Precipitate induces a number of undesired consequences. Characterization of precipitate has revealed the preponderant presence of free steryl glucosides (FSG) and monoglycerides (MG). These minor components may interact with moisture, exacerbating precipitate formation. Therefore, the effect of FSG, MG, and moisture content on precipitate formation and filterability of palm oil biodiesel (POB) was investigated. Blends of distilled palm oil biodiesel spiked with the minor components were prepared following a three-factor, five-level center composite design and tested for the cold soak filtration time (CSFT) and the precipitate content. CSFT was found to be influenced only by FSG whereas the precipitate content was found to be influenced by FSG, MG, and moisture. Increasing FSG increased precipitation at low levels of moisture; in contrast, when MG increased, the precipitate content decreased. Interaction with moisture exacerbated precipitation. A model capable of explaining 80% of the CSFT variability and a model capable of explaining more than 96% of the precipitate content variability were obtained using multiple regression analysis.