Process analysis and optimization of biocompatible diesel production from blended vegetable oils using KOH-impregnated eggshells derived CaO catalyst

The approach of feedstock blending for biodiesel production is one of the viable and cost-effective ways to reduce costs and overcome the logjams in feedstock availability. The present study investigates biodiesel synthesis from blended linseed-baobab seed oil (LOBO) via a transesterification process using a KOH-impregnated eggshell-CaO nano-catalyst (KOH/es-CaO NC). The catalyst was prepared through in-situ impregnation and calcination methods to obtain a K-modified CaO, which was further characterized using scientific analytical equipment: SEM, EDS, XRD, TGA, and FT-IR. The results revealed a meso-porous structured composite catalyst with a high content of CaO, and potassium containing species; K 2 Ca (CO 3 ) 2 , indicating its high basicity and potential activity in the transesterification of LOBO. A central composite design - response surface methodology (CCD-RSM) was used to examine the effects of independent variables on process efficiency. The model established an optimal yield of 94.04 wt% under the process conditions of molar ratio MeOH/LOBO of 18:1, KOH/es-CaO-900 loading of 5.5 wt%, and reaction 64 min, at a fixed temperature of 65 o C and agitation speed of 650 rpm. The statistical model, R 2 (0.9758), RMSE (0.46%), SEP (0.51%), and AAD (0.005%), confirmed the high ability and accuracy of the model with minimal deviation between experimental and predicted data. P < 0.0001 suggests a highly statistically significant regression model. Furthermore, the physicochemical properties of the synthesized catalyst revealed an enhanced durability and sustained activity potential for recycling across multiple applications in the biodiesel production process. The fuel characteristics of the biodiesel produced were found to conform to ASTM D6751, EN 14214, and SANS 1935:2011, making it a viable alternative fuel source to petroleum-derived diesel.