Abstract
Enzymatic grafting of kraft lignin (KL) on wood surfaces is presented as a non-leachable wood protection treatment. Scots pine and European beech mini-blocks were treated with KL solution in the presence of laccase isolated from Myceliophthora thermophila and the formation of a stable interaction between wood and lignin was observed. Furthermore, the same strategy was employed to graft KL with the simultaneous entrapment of copper in the polymeric net formed. Enzymatic treatment diminished the leachability of the compounds in accordance with the EN 84 standard. The durability of the leached wood blocks was evaluated by accelerated decay tests. Samples with grafted lignin on the surface lost their antifungal activity in long-term exposure at the concentration tested. This observation is in contradiction to the preliminary tests, where KL seemed to have some biocidal activity. On the other hand, KL grafting in combination with copper entrapment improved the decay resistance and the copper leaching was reduced.
Acknowledgements
This research has been financially supported by the Xunta de Galicia and by ERDF Funds (Projects EM2014/041 and GRC2013/003). C. Fernández-Costas is grateful to Universidade de Vigo [‘Research stays call (2014)’] for the financial support for a stay at CNR-IVALSA. We are also grateful to ENCE and Novozymes for providing raw materials and CACTI-Vigo for their technological support.
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