Copper Fixation by Way of a Pyrolytic Resin

CCA has been banned for residential use as a wood preservative in North America by the end of 2003. The alternatives will be copper-based chemicals, such as Ammonium Copper Quat (ACQ) or Copper Azole (CA). Leaching of copper from treated wood to environment will become one of the most important issues for the wood preserving industry. So far, no wood treatment with the new copper alternatives offers a long term fixation of copper in wood that last as long as CCA does. As a mean to improve the fixation of copper in treated wood, the formulation of a resin designed to penetrate and immobilize copper in the wood cells was undertaken. The use of a biomass-derived pyrolytic oil in the composition of this resin as a percentage of the total phenol base can also reduce the environmental impact associated with the use of petroleum-born phenol. Leaching tests have been conducted with 3 different formulations of resins, containing different ratios of pyrolytic oil : total phenol. The leachates were analyzed for the presence of copper using atomic absorption techniques. A reduction of copper leaching of around 20 times was observed when comparing the treatment with and without the resin. Variations were observed between wood species as well as between the resins containing different concentrations of pyrolytic oil. The organic leachate was characterized using gas chromatography and mass spectroscopy (GC/MS). Trace amount of organics, mostly acetic acid, was found in the leachate.