Comparison of the Release in Water of PCP Used for Preservation of Wood

Depending on their nature, chemicals used for preservation of wood behave differently when the treated wood samples are in contact with water. Pentachlorophenol and sodium pentachlorophenate are tested in this study. Picea specimens previously treated with each of these two chemicals, are immersed in water in two different ways: with a very large amount of water, with finite amounts of water in succession. The process of release in each case is controlled by diffusion with free principal diffusivities and a finite convective mass transfer coefficient. The principal diffusivities and convective coefficient are about the same for each chemical. The partition factor is quite different for these two chemicals. As a result, the kinetics of release are about the same for the two chemicals in a very large amount of water, while these kinetics differ notably when the release is made in a finite volume of water. A simple equation enables to calculate the amount of chemical remaining in the wood after several immersion stages made in succession in finite volumes of pure water