Exploring the thermal properties of biodiesel after purification via solvent-aided crystallization

Abstract

Cooking oil undergoes rigorous purification stages before reaching the market, which likely contributes to the elevated purity achieved through solvent-aided crystallization (SAC). However, the utilization of cooking oil as biodiesel feedstock is not suitable as it is expensive, resource inefficiency and lack of sustainability. Therefore, utilization of unpurified crude palm oil (CPO) for biodiesel production is an effective replacement. This study aims to assess the efficacy of SAC using unpurified CPO as the biodiesel feedstock. Parameters investigated include crystallization temperature (6 °C–14 °C), crystallization time (20–40 min), and shaking speed (32 rpm–84 rpm). Analysis reveals that CPO exhibits a high pour point of 15.7 °C and a cloud point of 10.8 °C, indicating potential operational and storage challenges. However, crude biodiesel derived from CPO demonstrates improved characteristics, including reduced pour point, cloud point, viscosity, and density, similar to the improvements seen in purified biodiesel obtained after SAC. The findings indicate that the most suitable operating conditions to maintain low pour and cloud points are a crystallization temperature of 10 °C, crystallization time of 30 min, and shaking speed of 61 rpm. Despite these improvements, both crude and purified biodiesel surpass ASTM D6751 limits for pour and cloud points, underscoring the necessity for further optimization in biodiesel production to meet industry standards. This research highlights the potential of SAC in enhancing biodiesel quality from unrefined feedstocks, offering a cost-effective and scalable method for producing higher-quality biodiesel while addressing current limitations.