Decay Resistance of Nano-Zinc Oxide, and PEG 6000, and Thermally Modified Wood

Abstract

In Central Europe, European beech (Fagus sylvatica L.) wood has a high potential for the production of construction and decorative materials, with the aim of replacing Norway spruce, oaks, and other traditionally used tree species. However, the biological resistance of beech wood—to decaying fungi, molds, and insects—is low, and in damp conditions its resistance must be increased with suitable preservatives or modification methods. In the present experiment, beech wood was first treated with water systems of nano-zinc oxide (0.1 to 3.3 wt.% of nano-ZnO) and/or polyethylene glycol 6000 (20 wt.% of PEG 6000), without/with additional thermal modification at 190 °C/2 h. In the presence of nano-ZnO, the decay resistance of beech wood to the brown-rot fungus Rhodonia placenta and the white-rot fungus Trametes versicolor significantly increased, mainly after its additional thermal modification. The presence of nano-ZnO in beech wood—(a) alone, (b) with a subsequent application of PEG 6000, (c) with additional thermal modification—had a more apparent inhibition effect on T. versicolor than on R. placenta. PEG 6000 alone did not improve the resistance of beech wood to rot.

Changes in Chemical Structure of Thermally Modified Spruce Wood Due to Decaying Fungi

“…As shown earlier [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 38 , 39 , 40 , 41 , 42 , 52 ], the higher mass loss of wood in the heating process, the more biologically durable the heat-treated wood. One of the generally accepted reasons for the higher decay resistance in heat-treated wood is due to the loss of hemicelluloses polymers in the cell walls [ 11 , 13 , 15 ].…”

“…Another important indicator of the degradability of wood during heat treatment is the lignin content, as it is a very thermally stable polymer [ 8 , 41 , 42 , 46 ]. The amount of lignin in the thermally treated spruce wood increased with an increase in the intensity of the treatment, that is, as a result of degradation of polysaccharides ( Figure 4 ).…”

“…Correlations between the content of wood components and the mass loss of the Norway spruce wood samples caused by thermal treatments. Heat treatment is generally less effective in protection against white-rot fungi compared to brown-rot fungi, which was shown at [40] for Pleurotus ostreatus and Coniophora puteana in Scotch pine (Pinus sylvestris) wood, at [41] for T. versicolor and Rhodonia placenta in thermally treated beech wood in presence of polyethylene glycol or at [42] for T. versicolor and Oligoporus placentus in Chir pine (Pinus roxburghii) wood.…”

“…The portion of galactose and arabinose in thermally-fungally attacked wood varied minimally. As shown earlier [11][12][13][14][15][16][17][18][19][20][21][22][23][38][39][40][41][42]52], the higher mass loss of wood in the heating process, the more biologically durable the heat-treated wood. One of the generally accepted reasons for the higher decay resistance in heat-treated wood is due to the loss of hemicelluloses polymers in the cell walls [11,13,15].…”

Decolorization of reactive dyes by the white rot fungus Phanerochaete velutina in presence of Zn and ZnO nanoparticles

“…In addition, ZnO-NP showed to have the most favorable properties compared to other wood protective nanoparticles (Kartal et al 2009). Therefore, ZnO-NP, along with copper and silver-based nanoparticles, are currently strongly investigated as wood protection agents (Kora 2022;Reinprecht et al 2022).…”