Paul I. Morris

Western red cedar extractives associated with durability in ground contact

Western red cedar (WRC) is well known for its natural durability. However, the roles of all the extractives that may be associated with this durability are not fully understood. The literature primarily credits the thujaplicins, with a lesser role for the lignans; however, previous work has identified highly durable material with low thujaplicin content. To elucidate the relative importance of various extractives, the decay resistance of WRC stakes at four test sites was compared with data on the content of specific extractives to determine whether there was any detectable association. The concentration of plicatic acid, a lignan, was associated with the decay resistance of WRC lumber in ground contact. An unidentified, unquantified compound (B) appeared to be similarly associated with decay resistance. The thujaplicins were only weakly associated with the decay resistance of WRC in ground contact.

Optimization of Copper Removal from ACQ-, CA-, and MCQ-Treated Wood Using an Experimental Design Methodology

AbstractThe development of appropriate disposal options for copper-based treated wood waste has been encouraged owing to stringent regulations regarding solid-waste landfilling or burning. Previous studies identified an efficient chemical process for removing metals from wood treated with chromated copper arsenate (CCA), alkaline copper quaternary (ACQ), copper azole (CA), and micronized copper quaternary (MCQ). The objective of this research was to identify optimal leaching parameters for removing copper from ACQ-, CA-, and MCQ-treated wood in terms of efficiency and operating costs. A 24 Box-Behnken design was used for determining influential parameters (sulfuric acid concentration, temperature, retention time, and number of leaching steps) on the copper removal and for identifying optimal leaching conditions. The results obtained showed that sulfuric acid concentration and number of leaching steps were the main influential parameters on copper solubilization from alternatively treated wood. The values ...

Sorption and capillary condensation in wood and the moisture content of red pine

The major purpose of this study is to improve hygrothermal simulation of wood responses to environmental vapor and moisture conditions under high relative humidity conditions. The article first reviews moisture property–related wood microstructures, sorption behavior, the concept of fiber saturation point, the potential for vapor to condense in wood under high relative humidity conditions, the measurement of equilibrium moisture content using traditional sorption methods, and the use of pressure plate test method at relative humidities above 95%. It then summarizes the results of equilibrium moisture content measurements for red pine sapwood at high relative humidity conditions using both sorption and pressure plate methods, with capillary saturation as maximum moisture content. It also discusses a number of wood microstructure and end-use-related factors that could influence the moisture content in service and the measurement of equilibrium moisture content in laboratory. Inconsistencies were found with other equilibrium moisture content data using the pressure plate test method.

Field Tests of Naturally Durable Species

Six wood species generally accepted to represent a range of natural durability were exposed in American Wood Protection Association (AWPA) E7-09 (ground-contact) and AWPA E25-08 (aboveground) decay...

Counter-current acid leaching process for copper azole treated wood waste.

This study explores the performance of a counter-current leaching process (CCLP) for copper extraction from copper azole treated wood waste for recycling of wood and copper. The leaching process uses three acid leaching steps with 0.1 M H2SO4 at 75°C and 15% slurry density followed by three rinses with water. Copper is recovered from the leachate using electrodeposition at 5 amperes (A) for 75 min. Ten counter-current remediation cycles were completed achieving≥94% copper extraction from the wood during the 10 cycles; 80–90% of the copper was recovered from the extract solution by electrodeposition. The counter-current leaching process reduced acid consumption by 86% and effluent discharge volume was 12 times lower compared with the same process without use of counter-current leaching. However, the reuse of leachates from one leaching step to another released dissolved organic carbon and caused its build-up in the early cycles.

Potential contributions of lignans to decay resistance in western red cedar

Abstract Recent work examining the correlations between heartwood extractives in western red cedar and decay resistance in ground-contact field tests identified two compounds that were moderately correlated with decay resistance—plicatic acid and an unknown compound. The aim of the present work was to identify the latter compound and to further probe the correlation between both of these lignans and decay resistance. Chromatographic and mass spectral data indicated that the latter compound was plicatin—the lactone of plicatic acid. Extractives fractions containing plicatic acid, plicatin, and polymeric lignans, believed to be derived from these compounds, were impregnated into ponderosa pine sapwood blocks and evaluated for their ability to resist decay by two brown-rot fungi. Impregnation of plicatic acid, plicatin, their combination, or polymeric western red cedar extractives in pine sapwood did not inhibit decay by the fungi evaluated. However, both plicatic acid and plicatin had high radical scavenging activity, and moderate ferrous iron chelating activity. It is proposed that these compounds contribute to decay resistance not as fungicides, but rather via alternative pathways. These could include interference with redox cycles associated with decay, and restricting moisture by reducing cell wall void volume.

Pilot-scale investigation of the robustness and efficiency of a copper-based treated wood wastes recycling process.

The disposal of metal-bearing treated wood wastes is becoming an environmental challenge. An efficient recycling process based on sulfuric acid leaching has been developed to remove metals from copper-based treated wood chips (0<x<12 mm). The present study explored the performance and the robustness of this technology in removing metals from copper-based treated wood wastes at a pilot plant scale (130-L reactor tank). After 3 × 2 h leaching steps followed by 3 × 7 min rinsing steps, up to 97.5% of As, 87.9% of Cr, and 96.1% of Cu were removed from CCA-treated wood wastes with different initial metal loading (>7.3 kgm(-3)) and more than 94.5% of Cu was removed from ACQ-, CA- and MCQ-treated wood. The treatment of effluents by precipitation-coagulation was highly efficient; allowing removals more than 93% for the As, Cr, and Cu contained in the effluent. The economic analysis included operating costs, indirect costs and revenues related to remediated wood sales. The economic analysis concluded that CCA-treated wood wastes remediation can lead to a benefit of 53.7 US

Improved Coating Performance on Wood Treated with Carbon-Based Preservatives and an Ultraviolet/Visible Light Protective Precoat

t(-1) or a cost of 35.5 US

Twenty-Year Performance of Decking with Two Levels of Preservative Penetration

t(-1) and that ACQ-, CA- and MCQ-treated wood wastes recycling led to benefits ranging from 9.3 to 21.2 US

Kraft pulping of wood treated with carbon-based preservatives.

t(-1).