Potential contribution of organosilicon compounds to reduced leaching of biocides in wood protection

Abstract

Abstract• Leaching of biocide treated wood leads to reduced effectiveness and potential threat to the environment.• Therefore the effectiveness of organosilicons as protective systems of biocides was evaluated. Scots pine sapwood specimens were impregnated with solely organosilicons and biocides as well as with combinations of both.• The biocides 3-iodo-2-propynylbutylcarbamate, propiconazole and 3-(trimethoxysilyl)propyldimethyloctadecyl ammonium chloride confirmed their effectiveness regardless the addition of an organosilicon. Low leachate toxicities to the crustacean Daphnia magna were found for the organosilicons, whereas significant leachate toxicities were measured for the biocides. Combining both did not considerably diminish the leachate toxicities.• It must therefore be concluded that under the circumstances as described in this article, organosilicons do not interfere with the efficacy of the biocides, but they do not contribute to a reduced leaching of the biocides either. Mots-clés :biocide / durabilité / écotoxicologie / organosilicone / protection du bois Résumé -Contribution potentielle des composes à base d'organosilicone pour réduire le lessivage de biocides dans le domaine de la protection du bois.• Le lessivage de bois traité avec des biocides conduit à une perte d'efficacité du traitement et à une menace pour l'environnement.• Nous avons donc évalué l'efficacité des organosilicones en tant que systèmes de protection des biocides. Des échantillons d'aubier de pin sylvestre ont été imprégnés selon trois modalités (i) avec uniquement des organosilicones, (ii) avec des biocides et (iii) avec une combinaison des deux.• Les biocides 3-iodo-2-propynylbutylcarbamate, propiconazole et 3-(trimethoxysilyl) propyldimethyloctadecyl chlorure d'ammonium ont confirmé leur efficacité quelle que soit l'organosilicone ajouté. Pour les traitements à base d'organosilicone, nous avons trouvé une faible toxicité des lixiviats (pour Daphnia magna) et une toxicité significative dans le cas des biocides seuls.• On peut conclure que dans les conditions expérimentales présentées les organosilicones n'interfèrent pas avec l'efficacité des biocides mais ils ne contribuent pas à une réduction de la lixiviation des biocides.

Durability of Epoxi-Oil Modified and Alkoxysilane Treated Wood in Field Testing

“…The above results suggest addition of biocides to further improve wood durability. On the other hand, De Vetter et al (2009) combination of organosilanes and biocides neither change the protective effectiveness of the treated wood nor reduce the toxicity of their leachates either. However, the authors have tested other alkoxysilanes and only in laboratory conditions.…”

Performances of white pine and white spruce treated with organic fungicides using an aqueous buffered amine oxide preservation system

“…Although similar performances were obtained for the white spruce while using only propiconazole, the use of AOs could also improve the depth of the impregnation of the fungicides and increase their resistance to leaching. De Vetter et al (2009) vacuum treated Scots pine with IPBC (1.5-2 kg/m 3 ) and a mix of IPBC (1.5-2 kg/m 3 ) and propiconazole (2.5-4 kg/m 3 ). They found nearly no mass loss after 16 weeks of exposure to C. puteana, which isn't surprising as this retention is way higher than the suggested retention for these products (EC Directive 98/8/EC 2007; EC Directive 98/8/EC 2008).…”

Preventive action of organosilicon treatments against disfigurement of wood under laboratory and outdoor conditions

“…The same combinations of organosilicons and biocides as used in De Vetter et al (2009b) were applied. Briefly, a 5 % solution of the DMS/n-OTES 2 was combined with (1) 0.3 % 3-iodo-2-propynyl-butyl carbamate (IPBC); (2) 0.3 % IPBC in combination with 0.6 % (±)-(cis+trans)-1-(2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolan-2-yl-methyl)-1H-1,2,4-triazole (propiconazole) and (3) 2 % 3-(trimethoxysilyl)propyldimethyloctadecyl ammonium chloride (Si-Quat).…”

“…However, most studies found that treatment of wood with organosilicons can only lead to a significant improvement of the investigated property when applied at (very) high concentrations (Hill et al 2004;Weigenand et al 2007;De Vetter et al 2009a). Treatments at lower, economically feasible concentrations lead to only modest improvements of the wood properties (Goethals and Stevens 1994;Mai et al 2005;De Vetter et al 2009b). Nevertheless, most of these authors conclude that wood treatment with an organosilicon may contribute significantly to prolong the service life of the wooden element when applied as part of a more complex (preservative containing) formulation for use class three applications like exterior cladding (Mai et al 2005;Donath et al 2006;De Vetter et al 2009a;b).…”