Impact of an Antioxidant on the Efficacy of Quaternary Ammonium Compounds (Quats) and Triazoles – Seven Year Above-Ground Study
Xiao Jiang, D Biro, W Holcombe
It has been reported that antioxidants have great potential for use with organic biocides in the area of wood protection. This paper demonstrates the impact of a low level of the antioxidant butylated hydroxytoluene (BHT) on the efficacy of quat-based and triazole-based formulations. A seven year lap joint test revealed a positive effect of BHT on the efficacy of quat-based formulations, especially at the low quat retention. The incorporation of BHT in a propiconazole-based system, however, showed an unexpected negative antioxidant effect at all levels tested. For tebuconazole- and cyproconazole-based formulations, the antioxidant effect on efficacy is slightly positive but insignificant. The influence of BHT on efficacy appears to diminish with increased active retentions in wood for both quat-based and triazole-based formulations, and in fact yields an adverse efficacy impact at high active retention levels. It is hypothesized that a larger amount of BHT is needed at high active retention levels to ensure the positive antioxidant effect. In addition, wood treated with BHT only showed slight protection for fungal decay, while the untreated controls exhibited severe decay with numerous failures.
Keywords: antioxidant, BHT, quats, triazoles, antioxidant effect, efficacy, above ground, and lap joints