“…Biodiesel is mainly composed of various fatty acid alkyl esters, which are related to the composition of raw materials ( Pan et al, 2018 ; Wang et al, 2018 ; Alagumalai et al, 2021 ). In general, biodiesel can be produced mainly through the transesterification of triglycerides of edible oil, vegetable oil, and waste edible oil, such as soybean ( Hu et al, 2020 ; Xie et al, 2021b ; Zhu et al, 2021 ), rapeseed ( Hájek et al, 2020 ; Gaidukevič et al, 2021 ), and Jatropha curcas oil ( Gutiérrez-López et al, 2021 ; Laskar et al, 2021 ), as well as the esterification of free fatty acids (FFAs) such as oleic acid (OA) with methanol. Recently, on account of the merits of microalgae, biodiesel production directly from microalgae oil has also attracted attention ( Zhang et al, 2015 ; Bauer et al, 2017 ; Abdala et al, 2020 ).…”