Pre-extracted radial sections of southern yellow pine sapwood were treated with CCA-C and analyzed by X-ray photoelectron spectroscopy (XPS). The ratio of C1 (carbon bonded to carbon and/or hydrogen) to C2 (carbon bonded to one oxygen) in XPS Cls spectra was taken as a measure of the progress of oxidation of wood components during CCA fixation. This ratio was 0.82 before CCA treatment and increased to 0.85 after 10 minutes soaking, to 1.0 after 1 hour soaking and decreased to 0.5 after 3 hours soaking. Oxidation of C2 to C3 (carbon bonded to two oxygens or a carbonyl group) was demonstrated by in situ trapping of C3 with ethylene glycol as they were formed. Further oxidation of C3 to C4 (carboxylic carbon: O-C=O) was not observed in the XPS spectra, as found by others. The hypothesis that rapid decarboxylation results in loss of C4 as evolved CO2 is supported by the observation that the C4 component of untreated wood was reduced by more than 90% after 10 minutes of CCA soaking followed by accelerated fixation and by the observation of CO2 evolution during early stages of accelerated fixation. The Cr(2p) spectra of CrVI and CrIII were established at 580.2 and 577.8 eV respectively. Accelerated fixation of CCA-C treated specimens resulted in complete reduction of CrVI to CrIII.

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