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Inedible vegetable-oil based biodiesel in Northern Viet Nam 191

In both cases, except for the first year, the cultivation was under a rain-fed
system with annual urea, phosphorus, and potassium fertilizer input. The
amount of mineral fertilizer use was changed due to the application of
composts from Hibiscus leaves and Pongamia and Hibiscus-Vernicia
oil cake. The management of the cultivation such as tillage, pruning,
and harvesting was done manually.
– Oil extraction: A three-phase solvent extraction system is used to obtain
sugar, medicinal compounds, and oil (Fig. 6.2). This method was recently
developed by a research group in Osaka Prefecture University as con-
tracted to the SATREPS Project. Water, methanol (MeOH), and
n-hexane are applied to extract sugar, vitamin E, and phytosterol and veg-
etable crude oil, respectively. Several valuable coproducts are derived
with high extraction efficiency. Accordingly, it was reported that 90%
of vitamin E and phytosterol and 95% of sugar and oil as their contents
in the seed were derived. Most of the solvents were recycled (90%), how-
ever about 10% of the total used solvents emitted to the air due to their
high volatility. The three-phase oil extraction was applied to Pongamia
and Vernicia seeds. Nevertheless, as the low component of medical com-
pounds in Hibiscus seed, only sugar and oil extraction were preferred.
– Biodiesel production: The two-phase reaction of biodiesel production from
vegetable oil is illustrated in Fig. 6.2. Depending on free fatty acid (FFA)
value biodiesel can be obtained via one-step/two-step transesterification
(Luu et al., 2014; Thanh et al., 2010), which encompasses two main stages
including the esterification process and the transesterification process.
Firstly, the esterification is performed using the molar ratio of methanol
to free fatty acids (FFA) of 6:1, 1wt% H 2 SO 4 ,65°C, and cosolvent is 30%
(wt/wt) acetonitrile. Secondly, the transesterification process is per-
formed in 30min with a methanol-to-oil molar ratio of 1:4 and 0.3wt
% potassium hydroxide (KOH), and 10% (wt/wt) acetone as cosolvent.
After the reaction, 90% of acetone and 25% of methanol are recovered.
Following the separation of glycerin, the solution is washed and dried.
The conversion yield of biodiesel is around 99%, and a total of 93% by
mass was obtained from crude oil. Accordingly, the obtained Pongamia,
Vernicia, and Hibiscus oils were collected and transferred to a transester-
ification reactor to produce biodiesel. Since FFA value of Pongamia oil is
>5% and that of Vernicia and Hibiscus are <5%, two-step and one-step
transesterification were applied to produce Pongamia biodiesel and Hibis-
cus and Vernicia blended biodiesel, respectively. The current capacity of
the biodiesel pilot plant of the SATREPS Project in Viet Nam is
500tonnes per year and will be upgraded to 1500 tonnes per year.