Characterization of CDDC (Copper dimethyl dithiocarbamate) Treated Wood

Abstract

This study investigates the chemical interaction between copper dimethyl dithiocarbamate (CDDC) and wood using various analytical tools such as environmental scanning electron microscopy (ESEM), X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transform-infrared spectroscopy (FTIR). ESEM and XRD reveal CDDC crystalline deposits on wood cell wall-lumen interface with approximate particle size of 29nm. XRD patterns specific to SDDC (sodium dimethyl dithiocarbamate) were observed on treated wood but disappeared after water washing. XPS confirms the presence of copper (II) on CDDC treated wood similar to that of pure CDDC powder. FTIR suggests that copper from the copper monoethanolamine complex interacts with wood components through ligand exchange. The exchange is likely between carboxyl groups from carboxylic acids or lignin phenolic groups and the 2-ethanolamine ligand of the copper complex. In the second step treatment, CDDC is formed through interaction between copper retained by carboxyl groups and dimethyl dithiocarbamate from SDDC. The negligible solubility of CDDC in water and the 95 % removal by organic solvent extraction suggest that CDDC crystals are attached in wood through physical interaction.