Wood preservative obtained by recycling – preliminary selection of leaching inhibitor

IRG/WP 08-50252

C Ibáñez, C Mantero, G Cecchetto, M Rabinovich, M Cerdeiras

Based on recycling of used household batteries, a process was developed to enable the recovery of major manufacturing components, leading to a solution of zinc (32 g.l-1) and manganese (15 g.l-1) salts, free of heavy metals. The potential use of the above solution as wood preservative was demonstrated by means of assays both of fungicidal activity -using white and brown rot fungi- and of insecticidal effectiveness –using termites. However, the application procedure assessed in previous work did not result in durable protection on account of the leaching of constituent metals as found for outdoor or high-humidity conditions. A preliminary study is here made of potentially efficacious chemicals in fixating the solution constituents in the wood tissue, and of alternative low-cost treatment procedures. In a first series of assays, Pinus taeda wood-blocks previously impregnated with the solution obtained by recycling and later treated with a solution of sodium borate (2%) separately by immersion and by brush-coating were used; while in a second series of assays, analogous experiments were made using a 2% sodium silicate solution. Following leaching tests, wood blocks were exposed to Coriolus versicolor (white rot fungus) and to Gloeophylum trabeum (brown rot fungus). Weight losses were compared for wood-blocks from either series, the use of sodium silicate appearing to lead to better results. Based on here results, further research should address the leaching of metals by means of field assays of the alternative treatment methods.

Keywords: metals, zinc, manganese, wood preservatives, borates, silicates

Conference: 08-11-30/12-02 Flamingo Beach, Costa Rica

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