Role of various nano-particles in prevention of fungal decay, mold growth and termite attack in wood, and their effect on weathering properties and water repellency

• Nano-ZnO showed promising leach resistance compared to the other nano-compounds and it was also slightly effective in decreasing water absorption.
• Nano-CuO and nano-SnO2 inhibited fungal decay by Trametes versicolor; however, almost all nano-compounds were effective in preventing decay by Gloeophyllum trabeum.
• While Nano-CuO and nano-B2O3 well-inhibited termite feeding, nano-ZnO and nano-CeO2 treatments resulted in only moderate termite resistance.
• Nano-ZnO and nano-B2O3 effectively inhibited mold growth.

The resistance of Scots pine wood vacuum-treated with nano-particles of ZnO, B2O3, CuO, TiO2, CeO2, and SnO2 against decay, mold fungi and subterranean termites was evaluated. Weathering and water absorption properties were also studied. Nano-ZnO only was resistant against leaching, while the other compounds leached out from wood specimens at more than 60% release rates. Mold growth in wood specimens was significantly inhibited by treatment with nano-ZnO and nano-B2O3. In Petri dishes, all mold fungi were also inhibited by nano-ZnO and nano-B2O3; however, nano-SnO2 inhibited Trichoderma harzianum growth only. Weight loss from fungal attack by the brown-rot fungus was significantly inhibited by all nano-compounds tested, except for leached specimens of nano-B2O3 treatments. Considerably higher weight losses were obtained in decay resistance tests by the white-rot fungus; only nano-CuO and nano-SnO2 were effective against this fungus. Nano-CuO and nano-B2O3 treatments produced favorable termite resistance in both weathered and unweathered specimens, while nano-ZnO and nano-CeO2 resulted in decreased weight loss in specimens exposed to termites. Nano-ZnO was slightly effective in decreasing water absorption. Exposing untreated wood specimens to artificial weathering resulted in significant changes in the chemical structure as determined by FT-IR analysis; however, weathering effect was somewhat decreased by the incorporation of the nano-compounds.