Laboratory Evaluation of Borate: Amine: Copper Derivatives in Wood for Fungal Decay Protection

This study aimed to evaluate borate:amine:copper derivatives in wood for fungal decay protection as well as the permanence of copper and boron in wood. Each of four derivatives of borate: amine:copper prevented fungal decay in wood. Disodium tetraborate decahydrate (borax):amine:copper derivatives with 0.61-0.63% retention after water leaching prevented decay by Gloeophyllum trabeum (Gt) and with 0.64% retention prevented decay by Trametes versicolor (Tv). Leaching did not decrease decay resistance for either Gt or Tv. Disodium octaborate tetrahydrate (DOT):amine:copper derivatives with 1.14-2.93% retention after water leaching prevented decay by Gt and with 0.54-1.19% retention prevented decay by Tv. Leaching decreased decay resistance to Gt but not to Tv. Higher copper and boron in disodium borax:amine:copper derivatives contributed to more decay resistance to Gt and Tv than that of DOT:amine:copper derivatives as evidenced by elemental analysis. IR spectra of wood treated with 5% borate:amine:copper derivatives after water leaching showed increased absorption at 1632-1635 cm-1 compared with the control. This increased absorption was partly attributable to carbonyl of copper carboxylates from oxidation of hemiacetals of hemicelluloses and cellulose by copper (II) ions and carbonyls of copper (II) quinone methides by oxidation of guaicyls by copper (II) ions. It was also partly attributable to carbonyls of copper carboxylates from hemicelluloses and phenolates from lignin through ion exchange reactions. These oxidation and ion exchange reactions of copper with wood components may account for their efficacy and long-term performance