A spectroscopic investigation of copper ethylenediamine fixation in wood
IRG/WP 99-20160
Xiao Jiang, J N R Ruddick
The fixation reaction which take place between copper ethylenediamine (Cu-en) solution and wood were expolored using X-ray photoelectron spectroscopy (XPS) and Fourier Transformed Infrared Spectroscopy (FTIR). The FTIR spectra revealed that copper reacts with the carboxylic acid and phenolic groups in wood to form stable complexes. The copper ethylenediamine complexes formed in wood were identified by comparing their XPS spectral parameters with those of similar compounds of known structure. The magnitude of the copper (2p3/2) binding energy of 934.64 eV is lower than that for copper(en)2 sulphate or copper acetate, suggesting that the copper is bonding to less reactive oxygen atoms in wood. This would support a principal reaction between copper and guaiacyl groups in lignin, similar to that suggested for copper-ammonia wood preservatives. The XPS spectra confirmed the ready reduction of the copper(II) in copper-amine treated wood during acquisition of the spectra. However, there was no evidence to suggest that this was occurring during fixation of the copper-amine chemicals. Further studies will explore competing reactions between copper and the wood components to form copper wood complexes with or without amine ligands present.