Wood-Gelatin Bio-Composite Membranes with Tunable Flux

Wood is an attractive bioresource for the production of functional materials, as it provides a complex hierarchical structure with unique properties. It is particularly promising for membrane applications due to its aligned micropores, which enable directed flow of liquids. However, wood-based functional membranes often rely on the combination of wood with nonecofriendly compounds or production methods. Furthermore, the performance of such membranes is predetermined by wood's intrinsic porosity, which cannot be regulated. Here we present a green sustainable biocomposite material for an application as tunable membrane by the combination of beech wood and gelatin. Investigation of the composite material with electron microscopy, X-ray microtomography, as well as FTIR-and Raman-spectroscopy shows, that the gelatin is distributed inside the cell lumina as thin film at the cell wall/lumen interface. The thickness of this film is tunable by the feed gelatin concentration. Furthermore, the gelatin forms meniscus-like structures that block vessels and hence impede capillary water transport through the wood structure. As a result, the flux of wood-gelatin composite membranes is tunable by both the sample thickness and the gelatin loading. The composites offer straightforward separation of wood and gelatin by immersion in warm water. Therefore, separate reuse or recycling of the constituents is possible. Due to its adjustability and eco-friendliness, the developed biocomposite provides a sustainable and versatile platform for membrane applications.