Izabela Ratajczak

Fixation of copper-protein formulation in wood: Part 2. Molecular mechanism of fixation of copper(II) in cellulose, lignin and wood studied by EPR

Abstract Electron paramagnetic resonance (EPR) spectra were recorded for copper(II) ions in cellulose, lignin and pine sapwood impregnated with a water based formulation containing CuSO4·5 H2O, tannic acid and animal protein SOLUTEIN. EPR parameters were derived from computer-simulated spectra. The parameters were interpreted in terms of molecular orbital theory giving coefficients of spin delocalization onto ligands. Five different spectra of chemically fixed complexes were identified. The complexes were octahedral with a different degree of elongation. For a copper concentration higher than approximately 0.5%, the additional EPR signal from the precipitated CuSO4·5 H2O salt appears. Two possible coordination sites are proposed for fixed copper complexes in cellulose structure and a single site is proposed for copper in a lignin. These complexes are different from the copper complex in wood, where Cu(H2O)4O2 octahedral complex exists with apical coordination to two oxygen atoms of deprotonated hydroxyl groups of polymeric units. When tannic acid is added to the impregnating solution, copper ions are strongly coordinated in a square-planar geometry of CuO4 and are easily leached. The copper-SOLUTEIN complex yields a distinguished EPR spectrum only in the impregnating solution, but not in the wood. Except for the copper(II) EPR spectra, where the signals from free radicals were detected in wood and lignin with a concentration in the order of magnitude of 1017 g-1 dependent on wood treatment.

Fixation of copper(II)-protein formulation in wood: Part 1. Influence of tannic acid on fixation of copper in wood

Abstract A new waterborne CuSO4·5 H2O-based formulation containing proteins from animal plasma SOLUTEIN (0.1%) as additive was investigated. Scots pine sapwood powder, cellulose and lignin were impregnated with solutions containing 0.1% and 2.5% copper (w/v). After impregnation, the samples were additionally treated by air-drying at 100°C or by tannic acid for denaturation of the proteins. Copper concentration was determined by atomic absorption spectroscopy and electron paramagnetic resonance (EPR). Copper introduced into wood by impregnation and eliminated by leaching was controlled. The maximum retention of 5.83 g kg-1 in wood was obtained when wood was treated with tannic acid (2.5%) after impregnation. For a formulation containing more than 0.5% of CuSO·5 H2O, precipitation of the salt in wood appears. Five different EPR spectra appeared in wood, cellulose and lignin after treating with SOLUTEIN and with tannic acid.

Moisture content (MC) and multinuclear magnetic resonance imaging (MRI) study of water absorption effect on wood treated with aminofunctional silane

The aim of this study was to determine susceptibility of aminoethyl aminopropyl trimethoxysilane (AEAPTMOS)-treated wood to absorption of liquid water. Absorbability was analysed by measuring absolute moisture content of wood and by MRI. These analyses were based on the results of previous studies on resistance against decay fungi in case of wood treated with the same chemical compound. In their previous studies the authors found that AEAPTMOS exhibits enhanced hydrophobic properties and thus increased resistance to the action of specific abiotic and biotic factors. The advantageous fungicidal properties of wood treatment systems indicate that AEAPTMOS may be considered as an environmentally friendly solution, being an alternative to conventional biocidal agents. Results indicate that this method may be used in laboratory analyses assessing the relative amount of water uptake through the wood surface.ZusammenfassungZiel dieser Studie war es, den Einfluss einer Behandlung von Holz mit Aminoethylaminopropyltrimethoxysilan (AEAPTMOS) auf die Aufnahme von flüssigem Wasser zu bestimmen. Die Absorptionsfähigkeit wurde durch Untersuchung des absoluten Feuchtegehalts von Holz und mittels Magnetresonanztomographie (MRI) ermittelt. Als Grundlage dieser Studie dienten Ergebnisse früherer Untersuchungen über die Fäuleresistenz von mit der gleichen chemischen Verbindung behandeltem Holz. Die Autoren kamen darin zu dem Schluss, dass AEAPTMOS verbesserte hydrophobische Eigenschaften bewirkt und somit die Resistenz gegenüber bestimmten abiotischen und biotischen Faktoren erhöht. Die guten fungiziden Eigenschaften dieser Holzbehandlungsmethode deuten darauf hin, dass AEAPTMOS als umweltfreundliche Lösung angesehen werden kann und eine Alternative zu herkömmlichen Biozidmitteln darstellt. Die Ergebnisse zeigen, dass diese Methode in Laboruntersuchungen zur Bestimmung der relativen Menge an durch das Holz aufgenommenem Wasser verwendet werden kann.

Silicon compounds as additives improving coating performance: fixation of silicon compounds with cellulose.

In this study the reactivity of cellulose with new solvent born preparations containing organosilanes, alkyd resin and natural oil was analysed. Structural analysis of cellulose after reaction with organosilanes and after extraction was performed using Fourier-transform infrared spectroscopy (FTIR). In IR spectra the analyzed bands included 1250 cm−1 responsible for vibrations of the SiC group and 800 cm−1 responsible for vibrations of SiC and/or SiO groups. These bands are characteristic of silicon bonds with atoms of carbon and oxygen originating from the methoxy groups found in organosilanes. The presence of these bands in the spectra proves the occurrence of a reaction between cellulose and organosilanes. The concentration of silicon was determined by AAS in cellulose after reaction with preparations and after extraction.

Protein impact on the capability of the protein-borate preservative penetration and distribution into pine and aspen wood

AbstractThe aim of the research project was to determine the capability of the protein-borate preservative to penetrate into the wood of Scots pine (Pinus sylvestris L.) and aspen poplar (Populus tremula L.). This capability was assessed by the preservative retention and the measurement of the penetration depth of the treatment solution. The scope of the performed experiments comprised two methods of treatment. The treatability of the two wood species with the examined formulations was compared with their treatability with the solution of the boric acid alone or with protein. The performed quantitative analysis of the boric acid and protein in individual wood layers allowed to characterise the distribution of the formulation ingredients on the cross-section of the treated elements. Significant differences were shown to occur in the degree of wood treatment with the formulation containing globular protein using the vacuum and vacuum-pressure methods. In addition, the impact of the protein presence on the way of boric acid penetration into wood was also determined. ZusammenfassungZiel dieses Forschungsprojekts war es, die Eindringfähigkeit von Holzschutzmitteln auf Proteinborat-Basis in Kiefern- (Pinus sylvestris L.) und Aspenholz (Populus tremula L.) zu bestimmen. Diese wurde anhand der Schutzmittelaufnahme und der Messung der Eindringtiefe der Imprägnierlösung bewertet. Zwei verschiedene Tränkverfahren wurden untersucht. Die Tränkbarkeit der beiden Holzarten mit den untersuchten Rezepturen wurde mit der von reiner Borsäure und reiner Proteinlösung verglichen. Anhand der durchgeführten quantitativen Analyse von Borsäure und Protein in den einzelnen Holzschichten konnte die Verteilung der Rezepturbestandteile im Querschnitt der behandelten Proben bestimmt werden. Mittels Vakuum- und Vakuum-Druck-Verfahren ergaben sich deutliche Unterschiede im Umfang der Imprägnierung mit der Rezeptur, die globuläres Protein enthält. Darüber hinaus wurde bestimmt, wie Protein die Eindringung von Borsäure in Holz beeinflusst.