Biogenic Synthesis of Copper and Zinc Oxide from Eucalyptus dunnii Leaves for Pinus elliottii Wood Preservation

The present study aims to evaluate the mechanical properties, colorimetric characteristics, and decay resistance of Pinus elliottii woods treated with oxides synthesized via green chemistry. For this purpose, an aqueous extract from Eucalyptus dunnii leaves was used to synthesize particles based on copper- and zinc-based oxides, as well as a binary oxide system (CuO/ZnO). Sodium polyacrylate was employed as a dispersant, impregnating the oxides into the wood through a horizontal autoclave using a modified Bethell process, assisted by a compressor, applying a pressure of 0.8 MPa for 30 min. The exposure to weathering aging did not significantly alter the mechanical properties of the samples, but it caused the leaching of particles from the treated wood surface, as shown by colorimetric results. Regarding the decay resistance, the copper-based oxide proved to be the most effective treatment against Trametes versicolor (a white-rot fungus), reducing mass loss down to 1.2%. The CuO/ZnO formulation reduced the mass loss caused by Gloeophyllum trabeum to 1.1%, while the zinc oxide showed minimal efficacy. Thus, oxides synthesized via green chemistry using aqueous leaf extracts and mild thermal conditions for synthesis and calcination proved effective in enhancing the wood resistance against biotic deterioration agents.