Natural durability of subfossil oak: wood chemical composition changes through the ages

Baar, Jan; Paschová, Zuzana; Hofmann, Thilo; Kolář, Tomáš; Koch, Gerald; Saake, Bodo; Rademacher, Peter

doi:10.1515/hf-2018-0309

Cited by 26 publications

(31 citation statements)

References 53 publications

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“…The findings indicate lower cellulose content and higher lignin content in fossil oak wood relative to recent wood. The proportion of lignin increased at the expense of polysaccharides, which are more sensitive to degradation and loss, especially in waterlogged conditions (Krutul et al 2010;Łucejko et al 2012;Bader et al 2013;Kolář et al 2014;Capano et al 2015;Baar et al 2019;Moosavinejad et al 2019). The disappearance of acetyl side chains and the cleavage of backbones in hemicelluloses are the main chemical alterations of waterlogged cell wall components in wood material.…”

Section: Introductionmentioning

confidence: 99%

Comparative archaeometric characterization of recent and historical oak (Quercus spp.) wood

et al. 2020

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The present paper studied the chemical composition of recent and historical oak wood comparing the extractive, holocellulose, α-cellulose, lignin, and ash contents. Comprehensive knowledge of the chemical components in recent and historical oak wood will facilitate the use of conservation agent in the restoration and conservation process of the investigated artifacts. The cyclohexane–ethanol extract of historical oak wood was significantly lower compared to recent wood, which can be explained by the leaching of extractives into the soil. No significant differences in the holocellulose and α-cellulose content of recent and historical oak wood were found. The lignin and the ash contents were significantly higher in the historical samples. The EDX analysis of the ash of historical oak wood showed remarkably higher iron content compared to the recent material. The result indicated the degradation of hemicelluloses in the historical sample. The significant difference in the amount of ash between the samples was explained by sediment materials that have been introduced into the wood from the soil. SEM imaging made these materials clearly visible as depositions in the cell lumens.

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Section: Introductionmentioning

confidence: 99%

Comparative archaeometric characterization of recent and historical oak (Quercus spp.) wood

et al. 2020

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“…In addition, the present animal feed analysis for the used raw material reports about an acidic detergent lignin (ADL) value of 1.6%. With respect to the reported values, the measured acidic insoluble residues, which are reported to be mainly analogous to Klason lignin [ 62 , 63 ], seem to be overestimated due to present proteins in the maize silage. Notwithstanding, an extraction step is regularly used before raw material analysis and is reported as important due to the possible precipitation of extracts or a limited access to the substrate resulting in incorrect lignin contents or too low carbohydrate yields [ 64 ].…”

Section: Resultsmentioning

confidence: 84%

Maize Silage Pretreatment via Steam Refining and Subsequent Enzymatic Hydrolysis for the Production of Fermentable Carbohydrates

Krafft¹,

Frey²,

Schwarz³

et al. 2020

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Maize, also called corn, is one of the most available feedstocks worldwide for lignocellulosic biorefineries. However, a permanent biomass supply over the year is essential for industrial biorefinery application. In that context, ensiling is a well-known agricultural application to produce durable animal feed for the whole year. In this study, ensiled maize was used for steam refining experiments with subsequent enzymatic hydrolysis using the Cellic® CTec2 to test the application possibilities of an ensiled material for the biorefinery purpose of fermentable carbohydrate production. Steam refining was conducted from mild (log R0 = 1.59) to severe conditions (log R0 = 4.12). The yields were determined, and the resulting fractions were characterized. Hereafter, enzymatic hydrolysis of the solid fiber fraction was conducted, and the carbohydrate recovery was calculated. A conversion to monomers of around 50% was found for the mildest pretreatment (log R0 = 1.59). After pretreatment at the highest severity of 4.12, it was possible to achieve a conversion of 100% of the theoretical available carbohydrates. From these results, it is clear that a sufficient pretreatment is necessary to achieve sufficient recovery rates. Thus, it can be concluded that ensiled maize pretreated by steam refining is a suitable and highly available feedstock for lignocellulosic biorefineries. Ultimately, it can be assumed that ensiling is a promising storage method to pave the way for a full-year biomass supply for lignocellulosic biorefinery concepts.

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“…Sessile oak is less rich in extractives than most of the other oak species. The total extractive content of sessile oak was found to be 3.4% in a recent study (Baar et al 2020).…”

Section: Resultsmentioning

confidence: 88%

Leaching effect of water on photodegraded hardwood species monitored by IR spectroscopy

et al. 2020

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Black locust (Robinia pseudoacacia L.), beech (Fagus sylvatica L.), aspen (Populus tremula L.) and sessile oak (Quercus petraea Liebl.) hardwood samples were irradiated by a strong ultraviolet (UV) emitter mercury lamp at 50 °C. Other series of specimens were exposed to a combined treatment of UV irradiation and water leaching. Ratio of UV radiation and water leaching time was 2:1. While the total duration of UV radiation was 20 days for both test series that of water leaching was 10 days. IR measurement was taken after both UV radiation and water leaching to monitor both effects separately. Lignin degradation proved to be more intensive in leached samples than in purely UV-irradiated samples. Guaiacyl and syringyl lignin showed similar degradation properties. Unconjugated carbonyl groups generated by the photodegradation were the most sensitive chemical components to leaching. Photodegradation generated two absorption bands of unconjugated carbonyl groups at around 1710 and 1760 cm−1 wavenumbers. The band at 1760 cm−1 was much more sensitive to water leaching than the band at 1710 cm−1. Three to ten days of water leaching was enough to remove all unconjugated carbonyls generated by the photodegradation, depending on the species. Sessile oak was the most sensitive species to water leaching, whereas black locust proved to be the most stable against both photodegradation and water leaching. Water was able to leach out unconjugated carbonyl groups (absorbing at 1745 cm−1) originally present in all investigated wood species.

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Natural durability of subfossil oak: wood chemical composition changes through the ages

Cited by 26 publications

References 53 publications

Comparative archaeometric characterization of recent and historical oak (Quercus spp.) wood

Comparative archaeometric characterization of recent and historical oak (Quercus spp.) wood

Maize Silage Pretreatment via Steam Refining and Subsequent Enzymatic Hydrolysis for the Production of Fermentable Carbohydrates

Leaching effect of water on photodegraded hardwood species monitored by IR spectroscopy

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