Fungal bioremediation of copper, chromium and boron treated wood as studied by electron paramagnetic resonance

Summary The structure of copper complexes in copper amine treated wood samples were elucidated by the application of electron paramagnetic resonance spectroscopy (EPR). EPR axial spectra were observed for all Cu-amine treated samples irrespective of the formulations. The values of A∥ and g∥ of the axial spectra indicate that the stereo-structure of copper complexes in copper amine treated wood was either tetragonal-based octahedral or square-based pyramidal. Comparison of electronic parameters of A∥ and g∥ in Cu-amine treated wood with those of the Cu-amine treating solution and the values in literature suggests that the interaction of wood with copper amine is through complexation in which wood functional groups are complexed with copper amine perpendicularly. The copper complexes in both treating solution and treated wood are in the form of CuN2O2, where copper is ligated with 2 nitrogen and 2 oxygen.

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Quantification of mobilized copper(II) levels in micronized copper-treated wood by electron paramagnetic resonance (EPR) spectroscopy

Holzforschung ◽

10.1515/hf-2012-0136 ◽

2013 ◽

Vol 67 (7) ◽

pp. 815-823 ◽

Cited By ~ 5

Author(s):

Wei Xue ◽

Pierre Kennepohl ◽

John N.R. Ruddick

Keyword(s):

Electron Paramagnetic Resonance ◽

Epr Spectroscopy ◽

Treated Wood ◽

Spectral Parameters ◽

Paramagnetic Resonance ◽

X Ray ◽

Acid Reaction ◽

Epr Signal ◽

Electron Paramagnetic ◽

Reference Samples

Abstract Sapwood sawdust from southern pine was treated with micronized copper (MC) under various conditions and the mobilized copper(II) (Cumob) concentrations were determined in the treated wood by electron paramagnetic resonance (EPR) spectroscopy. The spectral parameters for the copper sulfate (CuSO4)-treated sapwood and those of the MC-treated sapwood were very similar. A linear correlation was found between the intensities of copper (Cu) EPR spectra and those of Cu energy-dispersive X-ray fluorescence spectroscopy in a series of CuSO4-treated sapwood reference samples. Thus, the EPR signal intensities could be reliably correlated to the mass of reacted Cu present using this calibration curve. The amount of the Cumob in sawdust treated by MC suspensions increased during the first 2–3 days after the initial treatment and then reached a maximum during the 7-day monitoring period. In the case of the treatment with MC alone or MC azole, an increased MC concentration led to an elevated amount of Cu (to a maximum of ∼0.23% Cu) solubilized by the sapwood. If the wood was treated with MC quat, the Cumob initially increased, but at higher concentrations the Cumob content decreased, due to the interference by the quat cobiocide on the acid reaction between the wood and the basic Cu carbonate. An examination of commercially-treated wood confirmed the laboratory observations.

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Investigation of copper solubilization and reaction in micronized copper treated wood by electron paramagnetic resonance (EPR) spectroscopy

Holzforschung ◽

10.1515/hf.2011.188 ◽

2012 ◽

Vol 66 (7) ◽

pp. 889-895 ◽

Cited By ~ 6

Author(s):

Wei Xue ◽

Pierre Kennepohl ◽

John N.R. Ruddick

Keyword(s):

Electron Paramagnetic Resonance ◽

Copper Sulfate ◽

Epr Spectroscopy ◽

Copper Complexes ◽

Treated Wood ◽

Spectral Parameters ◽

Paramagnetic Resonance ◽

Copper Species ◽

Sulfate Solutions ◽

Electron Paramagnetic

Abstract The purpose of this study was to compare the reaction chemistry of micronized copper and alkaline copper treatments with wood and to determine how fast copper is solubilized during the reaction between the acidic functionality in wood and the basic copper carbonate (CuCO3). Copper species produced in wood by various treatment methods were analyzed by electron paramagnetic resonance (EPR) spectroscopy. The effects of time and solution concentration on the spectral parameters of copper complexes in sawdust treated with copper sulfate solutions were examined, followed by study on the structure and the rate of formation of the copper complexes in sawdust treated with basic CuCO3 suspension. The study further attempted to identify the soluble copper species formed in wood during treatment with micronized copper preservatives. Comparisons were made among the fixed copper complexes in wood treated with micronized copper preservatives, copper sulfate solutions, basic CuCO3 suspensions and alkaline copper solution. The results showed rapid formation of fixed copper complexes in wood treated with aqueous suspensions of basic CuCO3. These complexes can resist leaching, and they have similar stereochemistry to those formed between wood and copper sulfate. This finding supports the premises that soluble copper is generated during the treatment of sawdust with basic CuCO3, and it can bond to wood cell components by migrating into the cell wall in a manner similar to other soluble copper species. Such copper complexes formed are different from those of alkaline copper treated wood, which can be easily distinguished by EPR.

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