Reducing copper leaching from treated wood by sol-gel derived TiO₂ and SiO₂ depositions

Abstract

Abstract The antileaching efficacy of sol-gel-derived TiO 2 - and SiO 2 -based precursors has been evaluated through laboratory leaching trials with pine sapwood in two different ways. In a one-step process, wood was vacuum impregnated by the precursor solutions containing CuCl 2 . The copper (Cu) emission rates of the sol-gel-based impregnated woods were up to 70% lower than that of wood treated with pure CuCl 2 solution at the same level of concentration. More improvement (80%) could be achieved in a two-step process, in which sol-gel precursors were introduced into an already CuCl 2 -treated wood. The refinement was attributed to several effects. In the one-step approach, Cu was embedded in the TiO 2 /SiO 2 gels formed in the wood texture. During a two-step impregnation, gel layers that were formed in the wooden interior acted as an effective diffusion barrier. The sol-gel impregnations made wood more hydrophobic; therefore, the low amount of water that penetrated the cell wall was less efficient to leach out Cu.