Using the transesterification capacity of lipase to produce eco-friendly biodiesel is a promising method for the achievement of a Net Zero future. The method of immobilized lipase enhances the usability of the enzyme and improves its stability. Carbon-based magnetic nano-particles (C-MNPs) with nano-biochar as the precipitation core were prepared as the support to immobilize Candida antarctica lipase B (CalB) for biodiesel preparation. The nano-biochar particles were derived through the calcination of rice straw powder and subsequently ground to the nanoscale. FT-IR, XRD, SEM, and VSM results showed that the obtained C-MNPs with a diameter of 13–17 nm were showing excellent superparamagnetism, and effectively immobilized the lipase on them (CalB@C-MNPs). The optimal reaction conditions in a 100-mL stoppered flask for biodiesel production were dissolving 5 g soybean oil in 3 mL tert-butanol solvent, adding 1.16 mL methanol (molar ratio of methanol to oil 5:1), 0.15 mL water, and 0.2 g CalB@C-MNPs, and then shaking at 200 rpm and 30 °C for 24 h. Its primarily optimized conversion efficiency of biodiesel was 83.1 %. After repeated use of immobilized CalB for 8 cycles, the remaining activity and biodiesel yield were 79.7 % and 66.3 %, respectively. As a robust catalyst, CalB@C-MNPs exhibited outstanding transesterification efficiency, the ability for rapid recovery under an external magnetic field, and a promising candidate in biodiesel production.
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