Effects of new fixative additives on leachability of boron wood preservatives

IRG/WP 09-30507

A Mohareb, J Henry, E Wozniak, P Gérardin

Borates are well known with their protective capacity against both fungi and insects with low mammalian toxicity and environmental acceptable. However, boron itself does not ensure the appropriate protection for wood in the exterior applications because of their easily depletion from the treated wood under wet conditions. In this study, the potential use of monoglyceride and polyvinyl alcohol products as boron fixative agents was investigated. Two levels of these selected compounds (10%, 15% for the monoglyceride and 2.5%, 4% for the polyvinyl alcohol) were evaluated separately with three boric acid equivalent concentrations (1%, 2% and 4% BAE) in double vacuum impregnation processes using Scots pine sapwood and European beech specimens. Leaching was performed according to a laboratory leaching procedure (ENV 1250-2). Results of boron analysis using atomic absorption spectrometer (AAS) for the wood specimens and the leachates showed a significant reduction in boron leachability for the samples treated with both tested fixation additives when compared to the stand-alone boron-treated specimens. For boron protective additive treatments, the percentages of residual boron ranged from 20% – 37% of the initial boron retention. In all cases for these treatments, the detected boron retentions were above the toxic limit (1 kg BAE/m3) set for wood protection against basidiomycete fungi. Polyvinyl alcohol additive was the most promising product with approximately the same boron fixation effect but at lower levels when compared to the high levels of the tested monoglyceride compound.


Keywords: wood preservation, boron, fixation, leachability, monoglyceride, polyvinyl alcohol

Conference: 09-05-24/28 Beijing, China


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