FTIR Investigation of Wood Modifications Generating New Sites For Biocides (Copper) Fixation

摘要

This study was directed toward modifying the wood structure in order to generate new fixation sites for various iocide fixation. Among the functional groups targeted are carbonyl (-CH=O), carboxyl (-COO-) or carboxylic acid (-COOH), which can act as ligands to improve or increase, for example, the amount of copper fixed (leading to lower leaching rates). New copper fixation sites were generated on southern yellow pine (Pinus tadae) and soft maple sapwood (Acer rubrum) using various oxidation reagents. Crystalline cellulose powder was used as reference material to monitor the effect of these oxidation reagents. Chemical modifications observed after the treatment and the approximate amount of carboxyl/carboxylic acid groups generated by oxidation of alcohol (-CFb-OH) and/or carbonyl (-CH=O) groups from wood components relative to the untreated samples were examined using Fourier transform infrared spectroscopy (FTIR). The degree of oxidation after treatment with Na_2Cr_2O_7, agent AX, and H_2O_2 30%aqueous solutions was evaluated using the normalized values of the area ratio of the specific IR absorption bands ACOOH/A-CO-, relative to the untreated samples. The amount of carboxyl groups generated was correlated to the amount of absorbed copper. Theresults clearly suggest that significant copper fixation have occurred through the new carbonyl or carboxylic sites generated in the wood. The amount of copper retained in the treated wood, determined by atomic absorption spectroscopy (AAS), varies in the order: untreated < treated with H_2O_2 30% < Na_2Cr_2O_7 < agent AX. These findings confirm the correlation between copper fixed and the amount of active fixation sites in wood (functional groups which can act as ligands), strongly supporting a mechanism of copper fixation through coordination to -COO- sites.