Research Article Potential Wood Preservatives from Wood-Based Pyrolysis Oil Jerome E. Cooper, El-Barbary M. Hassan, Philip H. Steele and Brian Mitchell Forest Products Department, Mississippi State University, Box 9820, Mississippi State, MS 39762 USA jcooper@cfr.msstate.edu; emhassan@cfr.msstate.edu; psteele@cfr.msstate.edu; bmitchell@cfr.msstate.edu Correspondence should be addressed to Jerome E. Cooper, jcooper@cfr.msstate.edu Research to determine the potential for developing an alternative organic wood preservative system was conducted utilizing bio-oil produced from southern pine clear wood biomass. Southern pine feedstock was dried and pyrolyzed in an auger-feed reactor. Bio-oil treatments were diluted with 75% methanol to produce a bio-oil diluted to 25% concentration and impregnated into southern pine wafers either alone or with added biocides. The intrinsic fungicidal activity was evaluated against the brown-rot fungus, Gloeophyllum trabeum, using the AWPA Standard E-22 accelerated soil-block decay test. Three biocides (disodium octaborate tetrahydrate, tebuconazole and copper sulfate) were evaluated. Impregnated wafers were tested for compression strength loss following a 7-day leaching period. Treatments that combined tebuconazole or copper sulfate fungicides with 25% bio-oil resulted in reduced compression strength loss. Study results suggest that treating solutions combining 25% bio-oil with tebuconazole or copper sulfate fungicides may have potential as wood preservatives. 1. Introduction Wood products are attacked and degraded by many different organisms and must be treated with preservatives to perform satisfactorily in adverse environments. The estimated annual loss from bio-deterioration of wood products in the U. S. amounts to $500 million. Currently, the major wood preservative is chromated copper arsenate (CCA). Approximately 80% by volume of all treated wood products in North America, and over 95% of the treated lumber for residential applications, has been chemically treated with CCA [1]. However, due to recent public concerns over arsenic exposure, and beginning in January 2004, CCA is restricted to industrial applications. Several second-generation copper-organic preservative systems are currently available as alternatives to CCA for residential application, but these systems are about three-fold more expensive. Furthermore, these alternatives still contain toxic metals making them vulnerable to changes in public perception and restrictions on permissible products and end-uses. Indeed, this trend is already apparent in regulatory restrictions that are being applied in several European countries. Consequently, there is a need to develop cost-effective environmentally benign wood preservative systems for residential applications. Proper formulation of such a product would minimize concerns about human health as well as environmental issues. Previous research indicated limited fungicidal activity for neat bio-oil but a very significant synergistic effect was observed when bio-oil was combined with low levels of organic or metal biocides [2, 3]. Shultz and Nicholas indicated the potential for development of less expensive preservative systems from addition of antioxidants and water repellents to biocides with resultant synergistic multiplication of fungicidal activity [4, 5, 6]. Recent experimentation to determine the antifungal activity of bio-oils made from pine and oak wood and bark showed some effectiveness against both the Gloeophyllum trabeum (GT) brown-rot and the Trametes versicolor (TV) white- rot wood destroying fungi [7]. It appears that bio-oil has inherent antioxidant properties that result in a similar synergistic increase in biocide efficacy.