Valorization of tannery-derived FAMEs into bio-based epoxides via chemo-enzymatic synthesis

The urgent transition toward low-carbon chemical manufacturing has prompted the development of renewable alternatives to fossil-based epoxy intermediates. This study presents an integrated and resource-efficient chemo-enzymatic route for the synthesis of epoxidized methyl oleate (EMO) from fatty acid methyl esters (FAMEs) derived from tannery waste—a lipid-rich but underutilized industrial residue. A single-step urea complexation achieved 86.7 ± 0.6 % methyl oleate purity with a 38.1 ± 0.9 % recovery yield, while the saturated-rich co-product (∼40 %) exhibited physicochemical properties suitable for biodiesel or lubricant applications.

Subsequent epoxidation was carried out using immobilized Candida antarctica lipase B (Novozym® 435) and in situ generated performic acid, yielding an oxirane oxygen content of 6.42 ± 0.14 %, corresponding to >90 % conversion of double bonds under mild conditions. The enzyme retained 72 % of its initial activity after ten reuse cycles, significantly enhancing process circularity and reducing catalytic costs.

Green chemistry metrics were favorable: atom economy reached 86 %, solvent recovery exceeded 85 %, and the E-factor remained as low as 0.86 kg waste/kg EMO. A cradle-to-gate life cycle assessment (LCA) estimated a global warming potential (GWP) of 1.92 kg CO₂-eq/kg EMO—representing a 63 % reduction compared to petrochemical benchmarks. Economic analysis at the 1000 t/year scale yielded a production cost of €1.57/kg with an internal rate of return (IRR) of 15 %.

Overall, this work demonstrates how lipid-rich industrial residues can be converted into high-value bio-based epoxides through a scalable and environmentally sound chemo-enzymatic route, aligning with circular economy principles and green chemistry targets.