Parametric effects on kinetics of esterification for biodiesel production: A Taguchi approach

•Study of parametric effects on FFA-esterification kinetics for biodiesel production.•Taguchi method with standard orthogonal array design is used in this study.•Relative dominancy of parameters on XFFA is time-dependent.•Temperature dominates in the beginning but MR is more dominant in the later period.•Catalyst amount: minimal effect, constant-effect to rate of XFFAafter 75 min.

Parametric-effects on kinetics for biodiesel production from H2SO4–catalyzed esterification of free fatty acids (FFA) with methanol are evaluated at different intervals of reaction using Taguchi method. The parameters studied with orthogonal array design are catalyst loading, temperature, and methanol-to-FFA mole ratio (MR). Within the range of the parameters studied, each parameter has positive effect on conversion of FFA (XFFA) throughout the reaction wherein trans-esterification of oil is found negligible. But relative-contribution of temperature to XFFA declined ~23.5% (from 55.77% at 10 min to 32.39% at 180 min) and that of MR increased ~29% (from 21.46% at 10 min to 50.45% at 180 min). Catalyst loading has minimal effect on XFFA throughout the reaction (contribution varied within 15–24%) and has constant effect on FFA-esterification rate beyond 75 min. The relative effect of reaction time (as an independent parameter) along with other parameters is also evaluated at different reaction-phases and the orders of parametric-effects are compared with the results of the detailed analyses (using Taguchi approach) of esterification-kinetics data of published works for biodiesel synthesis. The relative parametric-effects on kinetics are found to be a function of reaction duration; parametric-order changes as reaction progresses toward equilibrium. However, temperature and MR are the more dominant parameters than catalyst loading and reaction time. Taguchi additivity model is validated with experiments and the predictions deviated within ±5%.

Graphical abstractRelative-contribution of reaction parameters to conversion of free fatty acids is a function of reaction time.Figure optionsDownload full-size imageDownload high-quality image (150 K)Download as PowerPoint slide