Diffusion in Wood.

Burr, Horace K.; Stamm, Alfred J.

doi:10.1021/j150451a019

Cited by 36 publications

(22 citation statements)

References 10 publications

(9 reference statements)

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“…Previous experiments on diffusion in wood have mostly utilized diffusion cells, measuring through diffusion of various ions (e.g., Cady and Williams 1935;Burr and Stamm 1947;Behr et al 1952;Narayanamurti and Kumar 1953). More recent studies attempt to study the time-dependent ion concentration profiles by cutting the wood samples at different times prior to analysis (Kazi et al 1996;Jacobson et al 2006;Kolavali and Theliander 2013).…”

Section: Introductionmentioning

confidence: 99%

Using fluorescent probes and FRAP to investigate macromolecule diffusion in steam-exploded wood

et al. 2018

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Diffusion of fluorescently labeled dextran of varying molecular weight in wood pretreated by steam explosion was studied with a confocal microscope. The steam explosion experiments were conducted at relatively mild conditions relevant for materials biorefinery at a pressure of 14 bars for 10 min. The method of fluorescence recovery after photobleaching (FRAP) was used to perform diffusion measurements locally in the wood microstructure. It was found that the FRAP methodology can be used to observe differences in the diffusion coefficient based on localization in the microstructure, i.e., earlywood, latewood, and cell wall. Microscopic changes due to steam explosion were seen to increase diffusion of the smaller 3-kDa dextran diffusion probe in the earlywood, while the latewood structure was not affected in any significant way. Macroscopic changes to the structure in the form of ruptures due to the steam explosion pretreatment were observed to increase the rate of diffusion for the larger 40-kDa dextran probe.

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Section: Introductionmentioning

confidence: 99%

Using fluorescent probes and FRAP to investigate macromolecule diffusion in steam-exploded wood

et al. 2018

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“…Another effect lowering both pore size distribution and porosity is the delineation of the cell wall. Reported average cell wall thickness values of Norway spruce are 3.52 µm and 2.90 µm in radial and tangential direction, respectively (Brändström 2002), while even values as low as 2.1-2.2 µm are reported by Havimo et al (2008) for cell wall thickness in tangential direction. Measurements on micrographs taken with a confocal microscope of a native wood sample yielded a cell wall thickness of 3-4 μm.…”

Section: Figmentioning

confidence: 96%

Lattice Boltzmann simulations of diffusion in steam-exploded wood

et al. 2019

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Diffusion of large molecules throughout the porous microstructure of wood pretreated with steam explosion was investigated by using the lattice Boltzmann method for simulations. Wood samples were investigated with high-resolution X-ray tomography to effectively reconstruct an accurate geometry of the structural changes that ensue after pretreatment. Samples of approximately 1 mm 3 with voxel sizes from 0.5 to 1 μm were examined with X-ray imaging. These large volumes, relative to what reasonably can be simulated, were divided into sub-volumes and were further reconstructed into geometries suited for the LBM simulations. The transient development of the concentration was investigated, and the effective diffusion coefficient at steady state was computed. Diffusion rates were found to increase significantly in the transversal direction due to the steam explosion pretreatment. The increase was observed both in the time needed for solutes to diffuse throughout the pores and in the effective diffusion coefficient. A shorter diffusion pathway and a higher connectivity between pores were found for the pretreated samples, even though the porosity was similar and the pore size distribution narrower than the native sample. These results show that local mass transport depends not only on porosity but also, in a complex manner, on pore structure. Thus, a more detailed analysis of pore space structure using tomography data, in combination with simulations, enables a more general understanding of the diffusional process.

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“…These methods have limitations and are not suitable to determine the concentration profiles. The most relevant investigations in this context have been identified (Cady and Williams 1935 ;Stamm 1946 ;Burr and Stamm 1947 ;Christensen 1951a,b ;Christensen and Williams 1951 ;Narayanamurti and Ratra 1951 ;Behr et al 1953 ;Narayanamurti and Kumar 1953 ;Stone and Green 1959 ;Fukuyama and Urakami 1980, 1982, 1986Siau 1984 ;Bengtsson and Simonson 1988 ;Robertsen 1993 ;Meijer et al 1996 ;Sharareh et al 1996 ;Kazi et al 1997 ;Cooper 1998 ;Ra et al 2001 ;T ö rnqvist et al 2001 ;Gindl et al 2002 ;Tsuchikawa and Siesler 2003 ;Jacobson et al 2006 ). There is no standard method for measuring diffusion into wood.…”

Section: Introductionmentioning

confidence: 99%

Determination of the diffusion of monovalent cations into wood under isothermal conditions based on LiCl impregnation of Norway spruce

Kolavali

Theliander

2013

Holzforschung

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Abstract:The impregnation of wood pieces in the course of pulping can be divided into primary (advective mass transport) and secondary (diffusive mass transport) penetration. Little is known about the latter partly because of the difficulties in the determination of the relevant diffusivities for this system. In the present article, a precise experimental methodology has been developed to measure the concentration profiles of cations as a function of wood piece dimensions, impregnation time, temperature, and wood structure. The cation concentration can be measured at any position in the impregnated wood piece. The impregnation of Norway spruce wood samples with LiCl was investigated. The impregnated wood pieces were cut mechanically into cubes, which were cut in slices by means of a microtome, and the eluate of the 0.4-mm-thick slices in HNO 3 was analyzed by flame atomic emission spectroscopy. The method gave reasonable results, and defects in the wood piece (microcracks) were detectable. The preliminary results presented here have to be verified with more replicates due to the heterogeneity of wood.

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Diffusion in Wood.

Abstract: Thesis submitted by . K. Burr to the University of Wisconsin in partial fulfillment of the requirements for the degree of Doctor of Philosophy, September, 1941.

Cited by 36 publications

References 10 publications

Using fluorescent probes and FRAP to investigate macromolecule diffusion in steam-exploded wood

Using fluorescent probes and FRAP to investigate macromolecule diffusion in steam-exploded wood

Lattice Boltzmann simulations of diffusion in steam-exploded wood

Determination of the diffusion of monovalent cations into wood under isothermal conditions based on LiCl impregnation of Norway spruce

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