Optimizing processes and performance of chromium- and arsenic-free wood preservatives

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Copper amine based wood preservatives such as alkaline copper quaternary ammonium compound (ACQ) have been given temporary registration as alternatives to chromated copper arsenate for consumer and residential uses. Relatively little is known about the fundamental mode of fixation or stabilization of these preservatives in wood and on processing variables that result in improved resistance to preservative leaching at the treating plant and in service. This project investigates the fundamental fixation mechanism of copper and quaternary ammonium compound components of copper amine preservatives in wood, by examining the speciation of stabilized copper and the changes to the wood chemistry. Effects of processing variables such as temperature, RH, solution concentration and wood species on rate and extent of stabilization of components will be evaluated.  Because of the importance of quality control procedures to ensure that the treated wood has been processed for optimal stabilization, methods of assessing degree of stabilization at the treating plant will be developed and evaluated. Implications of stabilization procedures on leaching of preservative components from wood in service will be assessed and diffusion models will be evaluated for their ability to predict emissions of both organic and inorganic components from wood when exposed to leaching conditions. The economic and technical feasibility of remediating treated wood removed from service by chemical extraction of active ingredients from spent wood as a potential recycling option will be investigated.