Process intensification of NaOH-catalyzed transesterification for biodiesel production by the use of bentonite and co-solvent (diethyl ether)

- The presence of bentonite and diethyl ether intensified the transesterification.
- High yield and fast reaction could be obtained at relatively low temperature.
- Response surface methodology was applied to optimize the process parameters.
- The optimal conditions led to a high FAME yield of 98.35 ± 0.69%.
- Kinetics and thermodynamic parameters of the transesterification were determined.

A novel transesterification process for biodiesel production has been developed. Bentonite was used as a water adsorbent to remove moisture from the biodiesel synthesis reaction system. Diethyl ether (DEE) was used as a co-solvent to improve the mutual solubility of oil and methanol. The influence of concentration of NaOH, DEE/methanol molar ratio, methanol/oil molar ratio, amount of bentonite, agitation rate, reaction temperature and reaction time was investigated. Response surface methodology was applied to optimize the main process parameters. The maximum FAME yield of 98.35 ± 0.69% was achieved under the optimized conditions of 0.56:1 of DEE/methanol molar ratio, 1.07 wt% concentration of NaOH and 5.65:1 methanol/oil molar ratio. The kinetics and thermodynamic analysis for this process was also carried out. The activation energy for the process was 23.73 kJ mol−1, and the thermodynamic analysis reveals that the net Gibbs energy change for the process was almost same as that for the bentonite-enhanced transesterification process.

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