Biodiesel production and comparison using commercial lipase and chemical catalyst from Cassia auriculata oil

In this present investigation, Cassia auriculata was explored as a feedstock for production of biodiesel. Transesterification reaction was performed by both enzyme (lipase) and chemical (potassium hydroxide) catalyst with diverse acyl acceptors such as methanol, ethanol, propanol, n-propanol, butanol, n- butanol, and finally their biodiesel yield were also recorded. Process optimization was performed by both one factor at a time method and response surface method. The maximal biodiesel yield of 92% (weight/weight) was obtained at the following optimal conditions: Oil:Methanol molar ratio of 1:6 (moles/moles), the lipase concentration of 2% (weight/weight), at 35 ​°C and 120 ​min. The highest biodiesel yield from Cassia auriculata oil was occurred with excess methanol that aids the equilibrium shift in the forward direction. The kinetics of the transesterification reaction was investigated under optimal conditions and the activation energy was found to be 14.91 ​kJ/mol. Simultaneously Gas Chromatography – Mass Spectroscopy was also carried out for the biodiesel produced from Cassia auriculata and the same has been reported. The GC analysis declares the existence of fatty acid esters like hexadecanoic acid methyl ester, methyl stearate and the peak with retention time 12.8 ​min signifies the evidence of hexadecanoic acid methyl ester with 28% of yield content. This investigation also evaluated the biodiesel quality produced from lipase-transesterified Cassia auriculata oil based on fuel properties. Biodiesel properties Flash Point (FC), Pour Point (PP) and kinematic viscosity were compared with American (ASTM 6751) and European (EN 14214) Standards. Cassia auriculata oil had PP 6.7 ​°C and Kinematic viscosity (813 ​kg/m3) that agreed with both the standards. Thus this study showed that Cassia auriculata oil could be a better fuel alternative with further improvement of fuel properties. [Display omitted] •Zn doped CaO nanocatalyst was effective in biodiesel production from Cassia auriculata oil.•The size and structure of the nanocatalyst was confirmed by FESEM, EDS and XRD.•The transesterification process parameters were optimized by conventional method.•The Cassia auriculata oil was successfully transesterified to biodiesel with the yield of 88.4%.