Eucalyptus oil encapsulated within calcium-crosslinked sodium alginate for natural wood preservatives against fungi and termite
Hailun Wang, Changying Ren, Weiguo Bai, Zhengjie Tang, Hong Lei, Heng Tian, Guanben Du
Abstract
Eucalyptus oil (EO) has attracted considerable interest as a promising wood preservative due to its antifungal properties, biodegradability, and low toxicity to vertebrates. However, its high volatility limits its application as a wood preservative. To resolve this problem, EO was encapsulated by sodium alginate (SA) crosslinked by calcium ions to achieve its sustainable release and the resulted EO@SA-Ca complex was then used as wood preservative to treat wood in this study. The results indicated that EO@SA-Ca showed better water resistance than EO with SA (EO@SA gel). Ca 2 + can cross-link with the carboxyl groups in SA to form a three-dimensional mesh structure wrapping EO. The rubberwood EO@SA-Ca treated achieved an acceptable decay resistance rating and could satisfy the requirements on class I defined in Chinese standard GB/T 13942.1–2009. Compared with the wood untreated, the mass loss reduced from 37.98 % to 8.73 % and 30.44–4.83 %, respectively, after 12 weeks’ exposure to white and brown rot fungi under 28 °C and 85 % relative humidity storage conditions. Microstructure analysis proved EO@SA-Ca treatment could protect internal structure of wood. The EO@SA-Ca treated rubberwood also showed significantly improvement on termite resistance. Compared with the wood untreated, the mass loss reduced from 5.72 % to 0.85 %. The results indicate that EO@SA-Ca as a wood preservative showed promising prospect in industry. • EO is a natural wood preservative, but its high volatility limits effectiveness. • Encapsulating EO in SA@SA-Ca created a sustained-release system, improving rubberwood decay resistance. • EO@SA-Ca is a natural, sustainable, and effective alternative to traditional wood preservatives for termites and fungi.