Taguchi Method and Grey Relational Analysis to Improve in Situ Production of FAME from Sunflower and Jatropha curcas Kernels with Subcritical Solvent Mixture

Abstract

This study investigates the possibility of employing in situ (trans)esterification (ISTE) under the subcritical condition (200–250 °C) of the solvent mixture (methanol + acetic acid) with a high solid loading and a low solvent to solid ratio (SSR). The Taguchi method together with grey relational analysis was used to improve both FAME yield and productivity. It was found that temperature reaction time and SSR were factors which contributed the most in obtaining high FAME yields. In addition to the above‐mentioned factors the addition of acetic acid also significantly improved the productivity. Employing the following conditions: 250 °C; 8.8 MPa; 3–7 mL/g SSR; 10 % acetic acid was found to provide an improved FAME yield and productivity. A confirmatory test resulted in a FAME yield of 87.5–92.7 % for sunflower kernels and 88.2–97.22 % for Jatropha curcas L. kernels and productivity up to 37.5 kg/m3/h can be obtained with good repeatability. Furthermore, the process developed in this study can tolerate moisture and a free fatty acid content of up to 25 %. The direct application of the method using whole kernels was also investigated.

Developments in in-situ (trans) esterification for biodiesel production: A critical review

“…Since sub and supercritical may proceed with and without catalyst, (trans)esterification may well occur also within the biomass. This was observed in the subcritical ISTE study of Sutanto et al [92] where whole sunflower kernels were utilized and a mixture of FAME and unreacted AG were still found in the solid residue. Solubilization and breakdown of biomass releasing the lipids could be possible since only about 10 wt% of the initial biomass was left after the reaction [79].…”

“…Solubilization and breakdown of biomass releasing the lipids could be possible since only about 10 wt% of the initial biomass was left after the reaction [79]. It was also observed that higher FAME yield was obtained from Jatropha kernels than sunflower kernels under the same reaction conditions despite the fact that Jatropha contains relatively higher lipids [92].…”

“…Fine particles with high lipid content tend to agglomerate and reduce effective surface area, thus a particle size of 500-1000 μm is recommended for supercritical ISTE of Jatropha kernels [20]. Sutanto et al [92] investigated ISTE of sunflower and Jatropha kernels, which were grounded to similar size and reacted under the same conditions. Despite containing higher extractable lipids Jatropha kernels resulted in higher yield (based on extractable lipid).…”

“…Except for hydrothermal treatments (Section 3.3.6), most other treatments do not produce useful side products to compensate for the cost incurred. In separate studies Go et al [82,92,98,99] provided alternative routes to directly utilize whole seed kernels, which avoid the need to reduce particle size.…”

Non‐catalytic and heterogeneous acid/base‐catalyzed biodiesel production: Recent and future developments

“…However, these techniques have not been widely used yet in the biodiesel production process. Techniques used in the latest studies of non‐catalytic and heterogeneous acid/base catalytic biodiesel production include artificial neural network (ANN), 151,152 response surface methodology (RSM), 63,103,151–154 and Taguchi method or orthogonal design 155–157 . Optimization studies on catalyst preparation step 158 and biodiesel properties 159 were also reported.…”