Abstract:
The aim of this work was to produce biodiesel from oil of tropical almond
(Terminalia catappa) seed using response surface method (Box-Behnken
design). Tropical almond seed oil was extracted using the Soxhlet extraction
technique, and the yield was 58.24%. The free fatty acid value was
1.48 mgKOH/g. A bifunctional heterogeneous catalyst of NaOH (20%)/kaolin
was synthesized to convert tropical almond (Terminalia catappa L.) seed oil
into biodiesel. NaOH and modified bifunctional kaolin were used as catalysts
via transesterification process to turn the oil into biodiesel. The
transesterification study findings demonstrated the effectiveness of the catalyst
for producing biodiesel. At modelling conditions of methanol-oil ratio (6:1),
catalyst amount (1.0 g), temperature (65 oC), stirring speed (600 rpm) and time
(30 minutes), the RSM predicted and validated biodiesel yields using NaOH as
catalyst were 96.38%, and 96.81% respectively. The synthesized bifunctional
catalyst (NaOH(20%)/kaolin) was characterised by means of XRD, FTIR,
SEM, and TGA. The yield of biodiesel generated using the
NaOH(20%)/kaolin catalyst was 95.94% at optimal parameter of catalyst
amount (2 g), temperature (65 °C), methanol-oil ratio (8:1), time (90 minutes).
For the forward response, a second-order kinetic process employing second
sections was suggested. The process of converting triglycerides to diglycerides
served as the rate-determining step for the whole NaOH (20 %)/kaolin
catalysed transesterification. The rate constant saw an increment from 0.014 to
0.037 min-1 as temperature was elevated from 50 to 65 oC. Based on how well
the physical and chemical characteristics of the produced biodiesel compared to ASTM D6751 standards, tropical almond seed oil was deemed to be
suitable feedstock for producing biodiesel.
