Central composite design for the optimization of CaO and Fe2(SO4)3 facilitated transesterification of Scenedesmus sp. oil for fatty acid methyl ester production

•Effect of CaO and Fe2(SO4)3 catalysts on FAME content of Scenedesmus sp. was tested.•Temperature, time, catalyst dose, methanol volume was optimized using CCD.•3% CaO, 80 °C, 120 min time, 6:1 methanol:oil showed 93% FAME.•FAME contains majorly 31.42%- C16:0, 23.45%- C18:1 and other PUFAs. The present research focuses on optimization of CaO and Fe2(SO4)3 facilitated transesterification conditions through central composite design (CCD) for maximal fatty acid methyl ester yield from Scenedesmus sp. At the outset, neutral lipid extraction of Scenedesmus sp. was done by Soxhlet method using hexane and it showed 13.6% neutral lipid. Conversion of neutral lipids to biodiesel was optimized using CCD and the parameters were 80 °C, 120 min reaction time, 3% CaO or Fe2(SO4)3 catalyst concentration and 6:1 methanol:oil ratio. Among the catalysts, 93% of FAME was produced at 3% CaO concentration in the above-said optimized process conditions. Biodiesel from Scenedesmus sp. oil facilitated by CaO catalyst showed 31.42% of C16:0 followed by 23.45% oleic acid and further, palmitoleic acid, linoleic acid and linolenic acid contents were at about 10.12, 10.67 and 11.92%, respectively, which signifies the use of CaO catalyst for industrial scale biodiesel production from Scenedesmus sp.