Alteration of the unsteady sorption behaviour of maple (Acer pseudoplatanus L.) and spruce (Picea abies (L.) Karst.) due to thermal modification

Abstract The aim of the present investigation was to evaluate the influence of a thermal modification on the kinetics of the water vapour sorption of maple (Acer pseudoplatanus L.) and spruce [Picea abies (L.) Karst.] based on the assumption that the Fickian equation can be applied in this regard in the first approximation. The unsteady-state sorption process between two equilibria of humidity was modelled as a diffusion process. The rate of sorption was recorded by the gravimetric method, and then the diffusion coefficient was determined through inverse parameter identification. The thermal modification leads to an alteration of the unsteady sorption behaviour of both wood species. Transport of water vapour decreases with increasing degree of modification. Depending on wood moisture, the trends of diffusion coefficients include all three levels of modification. Furthermore, the diffusion coefficients decrease when the thickness of specimens decreases. The calculated diffusion coefficients showed a length dependency both for unmodified and thermally modified spruce and maple. Accordingly, the results clearly show that these woods have a non-Fickian moisture transport behaviour. The results are nevertheless useful for comparative purposes.

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Sorption Kinetics of High Pressure Gases in Polymeric Tubing Materials

Volume 3: Safety and Reliability; Materials Technology; Douglas Faulkner Symposium on Reliability and Ultimate Strength of Marine Structures ◽

10.1115/omae2006-92393 ◽

2006 ◽

Author(s):

P. Jaeger ◽

S. Buchner ◽

R. Eggers

Keyword(s):

Diffusion Coefficients ◽

Gas Permeability ◽

Gravimetric Method ◽

Sorption Kinetics ◽

Operating Pressure ◽

Gas Solubility ◽

Atmospheric Conditions ◽

High Solubility ◽

Industrial Practice ◽

Kinetics Of

A gravimetric method was applied to determine the sorption kinetics of gases into polymers. Diffusivity as well as sorption capacity are determined directly. Data of gas permeability that are required for calculating leakage rates in polymeric flexile gas and oil ducts may be retrieved by multiplying the obtained diffusion coefficients and the gas solubility. In general carbon dioxide enters polymers to the highest extent. In industrial practice, the high solubility of CO2 e.g. may lead to explosive decompression of sealings once the operating pressure is reduced to atmospheric conditions. Diffusion coefficients are presented in the range of 75 to 130°C at 2 to 30 MPa.

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Investigating water vapour sorption kinetics of aluminium MOFs by powder X-ray diffraction

CrystEngComm ◽

10.1039/c9ce00132h ◽

2019 ◽

Vol 21 (15) ◽

pp. 2551-2558 ◽

Cited By ~ 2

Author(s):

Dominik Fröhlich ◽

Philipp Hügenell ◽

Helge Reinsch

Keyword(s):

Water Vapour ◽

Water Sorption ◽

Sorption Kinetics ◽

X Ray Diffraction ◽

Sorption Behaviour ◽

Water Vapour Sorption ◽

X Ray ◽

Vapour Sorption ◽

Kinetics Of

The water sorption behaviour of aluminium MOF CAU-10 and CAU-15-Cit was followed by in situ powder X-ray diffraction.

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Water vapour sorption properties of thermally modified and pressurised hot-water-extracted wood powder

Holzforschung ◽

10.1515/hf-2018-0301 ◽

2019 ◽

Vol 73 (12) ◽

pp. 1059-1068 ◽

Cited By ~ 6

Author(s):

Kristiina Lillqvist ◽

Susanna Källbom ◽

Michael Altgen ◽

Tiina Belt ◽

Lauri Rautkari

Keyword(s):

Water Vapour ◽

Thermal Modification ◽

Hot Water ◽

Water Extraction ◽

Hydroxyl Group ◽

Wood Powder ◽

Sorption Behaviour ◽

Hot Water Extraction ◽

Water Vapour Sorption ◽

Vapour Sorption

Abstract The objective of the study was to investigate the water vapour sorption behaviour of thermally modified (TM) wood powder, e.g. ground wood prepared from waste streams of TM solid wood, and wood powder that was extracted in pressurised hot water. Solid spruce wood was TM in steam conditions (210°C for 3 h), milled and hot-water-extracted (HWE) at elevated pressure (140°C for 1 h). The results evidence that the hot-water extraction reduced the water sorption and the accessible hydroxyl group concentration by the removal of amorphous carbohydrates. In contrast, the enhanced cross-linking of the cell wall matrix and the annealing of amorphous matrix polymers during thermal modification reduced the sorption behaviour of wood additionally, without further reducing the hydroxyl accessibility. These additional effects of thermal modification were at least partially cancelled by hot-water extraction. The results bring novel insights into the mechanisms that reduce the water vapour sorption of wood by compositional and structural changes induced by heating.

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Water vapour sorption of wood modified by acetylation and formalisation – analysed by a sorption kinetics model and thermodynamic considerations

Holzforschung ◽

10.1515/hf-2015-0015 ◽

2016 ◽

Vol 70 (3) ◽

pp. 203-213 ◽

Cited By ~ 20

Author(s):

Sarah Himmel ◽

Carsten Mai

Keyword(s):

Cell Wall ◽

Water Vapour ◽

Sorption Process ◽

Sorption Kinetics ◽

Constant Factor ◽

Sorption Data ◽

Sorption Behaviour ◽

Water Vapour Sorption ◽

Vapour Sorption ◽

Surface Work

Abstract The water vapour sorption data of untreated (Wuntr), acetylated (Wac) and formaldehyde-treated (WFA) Scots pine (Pinus sylvestris L.) sapwood were analysed in terms of their sorption kinetics and were transformed into excess surface work (ESW) isotherms. The sorption kinetics were studied by fitting the non-linear parallel exponential kinetics (PEK) model to the experimental data in which the sorption kinetics curve is composed of two processes (fast and slow components). Wac and WFA showed evident differences in their sorption kinetics and their thermodynamic sorption behaviour. In contrast to acetylation, formalisation influenced both the extent of the slow sorption process and the shape of its pseudoisotherm. For Wuntr and Wac, it appears that some water associated with the slow process is adsorbed at sites for fast sorption newly generated upon swelling (previously postulated as extra water) and subsequently desorbed by the fast process. For WFA, the formation of extra water hardly occurs. ESW was reduced through acetylation with a constant factor over the whole hydroscopic range, whereas the ESW of WFA was reduced only after reaching the monolayer capacity compared to its control. The sorption behaviour of Wac was solely determined by cell wall bulking, whereas that of WFA was governed by the increased matrix stiffness due to cross-linking of the cell wall polymers.

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Kinetics of catalytic conversion of methanol at higher pressures

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19803402 ◽

1980 ◽

Vol 45 (12) ◽

pp. 3402-3407 ◽

Cited By ~ 26

Author(s):

Jaroslav Bartoň ◽

Vladimír Pour

Keyword(s):

Low Temperature ◽

Reaction Kinetics ◽

Water Vapour ◽

Kinetic Data ◽

Catalytic Conversion ◽

The Given ◽

Kinetics Of

The course of the conversion of methanol with water vapour was followed on a low-temperature Cu-Zn-Cr-Al catalyst at pressures of 0.2 and 0.6 MPa. The kinetic data were evaluated together with those obtained at 0.1 MPa and the following equation for the reaction kinetics at the given conditions was derived: r = [p(CH3OH)p(H2O)]0.5[p(H2)]-1.3.

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Biosorption and Diffusion Modeling of Pb(II) by Malt Bagasse

International Journal of Chemical Engineering ◽

10.1155/2016/4210561 ◽

2016 ◽

Vol 2016 ◽

pp. 1-11 ◽

Cited By ~ 4

Author(s):

Klaiani B. Fontana ◽

Giane Gonçalves Lenzi ◽

Erica R. L. R. Watanabe ◽

Ervin Kaminski Lenzi ◽

Juliana A. M. T. Pietrobelli ◽

...

Keyword(s):

Sorption Process ◽

Isotherm Models ◽

Diffusion Modeling ◽

Biosorption Capacity ◽

Kinetic And Thermodynamic Parameters ◽

Pseudo Second Order ◽

Ph Optimization ◽

Kinetics Of ◽

And Diffusion

The removal of Pb(II) from water by biosorption processes onto malt bagasse was investigated and the kinetic and thermodynamic parameters were obtained; additionally a diffusion modeling was proposed. The characterization of malt bagasse was performed by FTIR and SEM/EDS. The experiments were conducted in batch system and an experimental design based response surface methodology was applied for agitation speed and pH optimization. The kinetics of biosorption followed pseudo-second-order model and the temperature of the process affected the biosorption capacity. Isotherm models of Langmuir, Freundlich, and Elovich were applied and the Langmuir model showed better fit and the estimated biosorption capacity was 29.1 mg g−1. The negative values obtained for ΔG° and positive values of ΔH° confirm, respectively, the spontaneous and endothermic nature of the process. The diffusion modeling was performed based on experiments in the absence of agitation to investigate the influence of the biosorbent on the sorption process of Pb(II) ions.

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A model to predict the kinetics of mass loss in wood during thermo-vacuum modification

Holzforschung ◽

10.1515/hf-2020-0127 ◽

2020 ◽

Vol 0 (0) ◽

Author(s):

Ottaviano Allegretti ◽

Ignazia Cuccui ◽

Nasko Terziev ◽

Laerte Sorini

Keyword(s):

Mass Loss ◽

Treatment Process ◽

Linear Trend ◽

Thermal Modification ◽

Thermal Treatments ◽

Temperature Profiles ◽

Relative Area ◽

Heat Power ◽

Kinetics Of

AbstractMass loss (ML) of wood caused by thermal degradation is one of the most important features of the thermal treatments and referred to as an indicator of intensity and quality of the process. The ML is proportional to the quantity of the effective heat power exchanged during the treatment process, represented by the area of the temperature profile versus time during the process. In this paper a model for the ML prediction based on the relative area was discussed. The model proposed an analytical solution to take into account the non-linear trend of ML when plotted versus temperature and time as observed in isothermal experiments. The model was validated comparing calculated and measured final ML of samples treated during thermal modification tests with different temperature profiles. The results showed that the relative area calculated in a transformed time-temperature space improves the correlation with the measured ML.

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