Adsorption of pinosylvin onto the structure of wood : mechanism and adsorption parameters

Abstract: Pinosylvin and polyhydroxybenzene derivatives are natural components of wood, known for their fungicidal/fungistatic properties. These components were used as adsorbates in the present investigation. Lignin and a-cellulose powder were used as model substrates in order to aquire information about the attachment of the adsorbates to the structure of wood. The adsorbate-substrate interaction was investigateded by the diffuse reflectance technique, commonly known as DRIFT. Furthermore, the adsorption of pinosylvin onto twelve different types of wood was studied, by means of the Raman microprobe technique. The effects of the solvents used, B.E.T. specific surface area, heat treatment and lignin content (as measured by the k-value), have been quantified by means of the Raman intensity ratios of characteristic peaks. The amount of solvent residue in each sample has been measured by the DRIFT technique. The morphology of the samples was investigated with the aid of scanning electron microscopy. In this licentiate work it was found that the adsorption is mainly due to the formation of hydrogen bonds. The lignin content and the composition of wood have significant effects on the surface concentration of pinosylvin adsorbed. The specific surface area of wood, as measured by the B.E.T. method, is rather low and does not diretly correlate with the amount adsorbed. The chemical changes after prolonged wood storage cause an increase in the hydrophobicity of wood, resulting in reduced adsorption efficiency.