Castor (Ricinus communis) and Sesame (Sesamum indicum) Biodiesel Optimization by Alkaline Na+/K+ Catalytic Conversion.

For the optimization of refined castor biodiesel (RCB) and refined sesame biodiesel (RSB), the impacts of specified conditions such as catalysts (NaOH and KOH), catalyst concentration (0.3–1.5), speed (500–750 rpm), and time (20–60 min) were investigated. The physicochemical properties of the RCB and RSB were measured using the American Standard for Testing Materials (ASTM) approved protocols for acid, peroxide, iodine, and saponification; density, kinematic viscosity, and refractive index values. Box–Behnken Design's Response Surface Methodology (RSM) was used for optimization. The results for four optimization methods were catalyst concentration (0.300–0.435 percent), speed (500.000–643.242 rpm), and time (20.000–31.386 min). The yield ranged from 81.062 to 102.648 percent, with a desirability range of 0.812 to 0.980 %. These yields were higher when compared to ASTM D 6751 which required a range of 46–55 % in regular biodiesel production. The RSB achieved a maximum yield of 102.649 % while using KOH, compared to 92.017 % in the RCB when using NaOH. The optimum yield of RCB using the KOH catalyst (89.461%) was higher to that of RSB using the NaOH catalyst (81.062%). The catalyst dosage and its nature, were the most essential factor during biodiesel optimization