A wood-based fluid catalytic reactor with directional channels and porous inner walls for efficient degradation of 4-NP by immobilized laccase

Modern bioreactors primarily focus on fixing enzymes on materials to form fixed bed reactors, but the reaction efficiency is unstable. More importantly, the enzymes easily fall off or even inactivate, and the fluid risks leaking due to excessive pressure during flow. In this study, a directional channel continuous microfluidic reactor with laccase covalently immobilized in the internal channel is made from natural wood. After dimethylacetamide/lithium chloride (DMAc/LiCl) treatment of delignified wood, the micropores (ray cells, pits and nanopores) in directional channel walls are fully exposed. When the fluid passes through, the turbulence near the pits increases, resulting in good mass and heat transfer, which enhances the catalytic efficiency of laccase. The reactor has good stability and maintains more than 80% substrate conversion in the pH range of 3–7 and the temperature range of 15–55 ℃. In the degradation of 4-nitrophenol (4-NP), a 94.42% degradation rate is achieved in only 30 min, and 86.93% efficiency is maintained after 25 cycles of catalysis, indicating its excellent reusability. The directional reactor with porous inner walls is simple to prepare and easy to scale up, which provides excellent convenience for continuous industrial production and shows great commercial application potential.