Acid-Catalyzed Pretreatment Of Hevea Brasiliensis (Rubber) Oil Via Esterification Process: Modeling And Optimization Studies
Keywords:
Hevea brasiliensis oil, free fatty acid, pretreatment,, esterification,, modelling,, optimization,, response surface methodologyAbstract
The present study investigated modelling and optimization of acid esterification of non-edible Hevea brasiliensis (rubber) oil towards reduction of its very high free fatty acid (FFA) content (22.2 ± 0.03%) using response surface methodology (RSM). The process variables examined in the esterification reaction were methanol-to-oil molar ratio (15:1 – 30:1), H2SO4 concentration (1 – 2 wt.%), reaction temperature (55 – 65 °C) and reaction time (1 – 2 h) by central composite design (CCD). A second-order polynomial model was developed to assess significant synergistic impact among the process variables on the FFA content of the oil. Methanol-to-oil molar ratio had the most significant impact of the process variables. Optimal condition for the FFA reduction was achieved as methanol-to-oil molar ratio of 25.74, H2SO4 concentration of 2.00 wt.%, reaction temperature of 63.04 °C and reaction time of 1.51 h with predicted FFA content of 1.02%. Confirmatory test of the predicted optimal condition in the laboratory gave an average FFA content of 0.99 ± 0.021%, which corresponds to 95.5% conversion. Thus, the model obtained could be used for processes employed for the pretreatment of oils with high FFA content, which inhibits their conversion to biodiesel via transesterification process.Hevea brasiliensis oil
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