Fe3O4-poly(AGE-DVB-GMA) composites immobilized with guanidine as a magnetically recyclable catalyst for enhanced biodiesel production

This present research aims at developing an efficient and reusable base catalyst to improve the biodiesel production for the need of green chemistry and sustainable development. To achieve this, the copolymer, namely poly(allylglycidyl ether-divinylbenzene-glycidyl methacrylate) (poly(AGE-DVB-GMA)), was firstly incorporated in the Fe3O4 nanoparticles forming magnetic Fe3O4-poly(AGE-DVB-GMA) composites, and then organic guanidine was bound on the magnetic matrices via covalent bonds with active epoxy groups. The characterization of the as-made magnetic copolymer support and solid base catalysts was performed by several techniques, and the results revealed that the guanidine base was successfully tethered on the magnetic copolymer support. This developed solid catalyst possessed large surface basicity of 2.45 mmol/g and highly magnetic responsiveness with saturation magnetization value of 18.13 emu/g, displaying good activity to the transesterification of soybean oil to biodiesel in a heterogeneous manner. Under the transesterification conditions of methanol/oil molar ratio of 20:1, catalyst dosage of 7 wt%, reaction temperature of 65 °C, reaction duration of 8 h, the biodiesel yield of 92.6% was attained over the guanidine-based solid catalyst. Moreover, the catalyst could be easily separated under an external magnetic field, and showed satisfactory catalytic activity even after four reuse cycles, thus posing considerable potential for the sustainable and clean production of biodiesel.