The Chemistry of Micronized Copper Treatments: Possible Roles for Unreacted Basic Copper Carbonate

摘要

Micronized copper preservative treatments of softwoods result in mobile copper being formed by reaction with the carboxylic acid functional groups in hemicellulose and pectic substances present in wood. Typically the amount of reacted copper formed isless than 0.3% Cu m/m. The current project describes two aspects where remaining unreacted basic copper carbonate can become mobile and complex in treated wood. The two aspects considered are a) lodgepole pine heartwood colonized by decay fungi in the living tree, and b) long term soil exposure of treated wood. Reacted copper concentrations were found to be enhanced in lodgepole pine heartwood that had been produced from trees containing white rot. The presence of the copper resin products can be detected by a change in the EPR parameters. Micronized copper treated wood exposed in soil for 40 months, showed enhanced reacted copper levels, with values as high as 0.65% Cu (m/m). It is hypothesized that fulvic acid reactions allow the reacted copper concentration to increase, although the lack of changes in the EPR parameters suggests the final products are similar to those usually formed with glucuronic acid.