Novel Lignin-Propiconazole Nanocapsules Are an Effective Bio-Based Wood Preservative

Wood is a precious bioresource that has been utilized from ancient times for fuel, timber, and as a raw material for tools, weapons, and paper. The world produces approximately 1400 million m³ of wood annually. However, a considerable portion decays before it can be utilized, predominantly by fungi. This results in significant economic losses and resource depletion. To avoid these issues, wood preservation is employed to increase the stability and the durability of wood. Chemical preservatives are the most common treatments, but these are known to have adverse effects on the environment. Similarly, water-soluble, organic preservatives are only partially effective and are more prone to leaching. In this work, a novel, effective, sustainable, and environmentally-benign wood preservative is presented. Water-dispersible double-shell, hollow lignin nanocapsules were produced from kraft black liquor, strategically oriented to enhance the inherent biocidal properties of lignin. The nanocapsules were loaded with organic propiconazole to act as a secondary biocidal agent. The system was tested for its synergistic efficacy at combating Gleophyllum trabeum decay in southern yellow pine wood. The preservative successfully penetrated the wood block, and following three months of soil-jar incubation, only 19.95 ±2.05 % weight loss was observed from vacuum impregnation as opposed to 41.58 ±9.51 % control weight loss.