Unique 3D interpenetrating capillary network of wood veneer for highly efficient cross flow filtration

Natural wood is mainly comprised of numerous long, partially aligned channels which are connected by micropores (such as ray cells, pits) providing high-efficiency nutrient transportation corridor. Here, thin wood veneer (the thickness of 400 μm) was used to design catalytic membrane for water treatment with reversed-tree transport pathways. As filtering direction is nearly perpendicular to wood growth direction, wood veneer possesses abundant sinuous water channels based on partially aligned and interconnected cell lumens which provide long enough micro reaction and suitable water transfer pathways in a greatly reduced thickness. Meanwhile due to a small rotary cutting angle, large number of incisions of vessels and fibers were formed ensuring large inlet area for fluid transport. And mussel-inspired polydopamine (PDA) was used to modify the surface of wood pores with highly active functional groups. Then, Pd nanoparticles could be in situ grown and immobilized onto wood channels via these groups (Pd/PDA/wood veneer). On account of the unique 3D interpenetrating capillary network structure, Pd/PDA/wood veneer shows a highly efficient water treatment for methylene blue (MB) solution. The flux of Pd/PDA/wood veneer can reach 3462 L/(m2h) with high MB removal efficiency (> 95%), meanwhile it shows good mechanical strength and flexibility. The designed thin wood veneer with unique structure exhibits promising results for practical wastewater treatment and even wider applications such as solar-thermal conversion, microreactor design.