Efficient production of biodiesel with promising fuel properties from Koelreuteria integrifoliola oil using a magnetically recyclable acidic ionic liquid

In the present study, catalytic production of biodiesel from a new alternative non-edible feedstock Koelreuteria integrifoliola ( K. integrifoliola ) with a Brönsted-Lewis acidic ionic liquid (IL) immobilized on a magnetic support Fe 3 O 4 @SiO 2 (FS-B-L-IL) was investigated for the first time. Excitingly, K. integrifoliola contains a high oil content (54.05%) with an average acid value (AV) of 4.66   mg KOH/g. Furthermore, the FS-B-L-IL catalyst was characterized with XRD, FT-IR, SEM, HR-TEM, TG, pyridine-IR and VSM. It was found that FS-B-L-IL possessed a uniform core-shell structure with strong magnetic responsiveness, and showed high activity in simultaneously catalytic transesterification and esterification of crude K. integrifoliola seed oil (CKISO), giving fatty acid methyl ester (FAME) yield of 93.7% under optimal conditions. The reaction followed pseudo-first order kinetics and the activation energy was calculated to be 62.6   kJ/mol. In addition, FS-B-L-IL exhibited a heterogeneous catalytic behavior and could be recycled for at least five times with negligible loss of activity. The main fuel properties of the obtained K. integrifoliola biodiesel were also evaluated, which were comparable to specifications prescribed in the ASTM D6751 and EN 14214.