Biodiesel production from tropical almond (Terminalia Cattapa L.) Seed oil

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.