Topic: Continuous Enzymatic Peracids Synthesis in Pickering Emulsions: Influence of Nanoparticles Modification,...

The lipase-catalyzed oxidative functionalization of alkenes in Pickering emulsions (PE) offers a green and efficient alternative to conventional processes involving hazardous oxidants. Other investigated reaction media used for this alternative green pathway still suffer from enzyme deactivation and /or low specific reaction rate which limits their industrial adaptability. This study investigates the enzymatic synthesis of peroxyacetic acid, the first step in lipase-catalyzed oxidative functionalization, in a continuous membrane reactor. The effects of aqueous phase composition, modified silica nanoparticles, and operational parameters on reaction performance were systematically studied. Optimal conditions were obtained at pH 7, 100 mM buffer, and 5 g L_dp ^{- 1} enzyme concentration. Surface-modified silica nanoparticles improved PE stability and interfacial catalytic efficiency, while maintaining comparable catalytic productivity. Hydrogen peroxide outperformed urea hydrogen peroxide, yielding a maximum product yield of 83% at a concentration of 45 mM in the influent solution and a space-time yield of 44.9 g_PAL^{- 1}d^{- 1} at 386 mM. At 386 mM, the specific reaction rate (17.5 mmol g^{- 1} h^{- 1}) was over twice that of reported single organic-phase systems. Despite the high peroxide concentrations, the enzyme displayed remarkable stability in PE due to the protective role of nanoparticles. This work provides critical insights into optimizing enzymatic oxidative functionalization in PE and their potential for sustainable industrial applications. Practical application: This study provides a foundation for the development of sustainable and efficient continuous processes for oxidative biotransformations using Pickering emulsions (PE). By enabling the enzymatic production of peracids, the first step in lipase-catalyzed oxidative functionalization, the process addresses key limitations of previously explored green reaction systems, such as enzyme deactivation and low specific activity. The PE system enhances emulsion stability and preserves enzyme activity under high oxidant concentrations, achieving high yields and space-time productivity in a membrane-based continuous reactor. Surface-modified silica nanoparticles further improve interfacial catalytic efficiency as well as emulsion stability. This approach is well-suited for selective and eco-friendly oxidation in the synthesis of fine chemicals, active pharmaceutical ingredients, and specialty materials. Additionally, the robustness of the system allows stable operation under harsh conditions, supporting the efficient integration of the second, chemical epoxidation step. These findings contribute to the broader implementation of continuous green chemistry technologies in industrial biocatalysis.