Distribution and oxidation state of copper in the cell walls of treated wood examined by synchrotron based XANES and XFM

Abstract

Recently, synchrotron based X-ray fluorescence microscopy (XFM) and X-ray absorption near edge spectroscopy (XANES) were used to examine the metal fastener corrosion in copper-treated wood. XFM is able to map the copper concentration in the wood with a spatial resolution of 0.5 µm and is able to quantify the copper concentration to within 0.05 µg cm^-3. XANES was used as a complimentary technique to differentiate between oxidation states of copper in the wood. While the primary goal of these measurements was to better understand the corrosion mechanisms, the measurements also give insights into the amount, distribution, and ionic states of copper in various wood preservatives. In this paper we show how synchrotron based XFM and XANES can be used to map out the concentration of copper within the cell walls along with the oxidation state, as a potential tool for better understanding treatment and fixation with copper based preservatives. Data are presented for alkaline copper quaternary (ACQ-D), chromated copper arsenate (CCA-C), copper azole (CA-C), and a micronized copper quaternary formulation (MCQ). The data suggest a large fraction of the copper is in a copper (I) oxidation state.

Citation

Zelinka, Samuel L.; Kirker, Grant T.; Jakes, Joseph E.; Passarini, Leandro; Lai, Barryl. 2016. Distribution and oxidation state of copper in the cell walls of treated wood examined by synchrotron based XANES and XFM. In: Proceedings of CORROSION 2017. American Wood Protection Association: 172-178.