scholarly journals A New Method for the Measurement of the Diffusion Coefficient of Adsorbed Vapors in Thin Zeolite Films, Based on Magnetoelastic Sensors

Sensors ◽  
2020 ◽  
Vol 20 (11) ◽  
pp. 3251
Author(s):  
Dimitris Kouzoudis ◽  
Theodoros Baimpos ◽  
Georgios Samourgkanidis
Keyword(s):  
Diffusion Coefficient ◽  
Organic Compound ◽  
Diffusion Coefficients ◽  
Volatile Organic ◽  
Adsorption Data ◽  
Order Of Magnitude ◽  
Type Zeolite ◽  
Magnetoelastic Sensors ◽  
Zeolite Films ◽  
First Time

In the current work an experimental method is used in order to calculate the diffusivity D (diffusion coefficient) of various vapors in thin zeolite films. The method is based on adsorption data from magnetoelastic sensors on top of which a zeolite layer was synthesized, and the diffusivity is extracted by fitting the data to Fick’s laws of diffusion. In particular, the method is demonstrated for two volatile organic compound (VOC) vapors on two different zeolites, the p-Xylene adsorption in Faujasite type zeolite with D = 1.89 × 10 − 13   m 2 / s at 120   ° C and the propene adsorption in Linde Type A type zeolite with D = 5.9 × 10 − 14   m 2 / s at 80   ° C , two diffusion coefficients which are extracted experimentally for first time. Our results are within the order of magnitude of other VOC/zeolite values reported in literature.

Transport of Neutral Solute Across Articular Cartilage: The Role of Zonal Diffusivities

2015 ◽  
Vol 137 (7) ◽  
Author(s):  
V. Arbabi ◽  
B. Pouran ◽  
H. Weinans ◽  
A. A. Zadpoor
Keyword(s):  
Experimental Data ◽  
Diffusion Coefficient ◽  
Diffusion Coefficients ◽  
Equilibrium Concentration ◽  
Cartilage Tissue ◽  
Zone Model ◽  
Superficial Zone ◽  
Time Curve ◽  
Order Of Magnitude ◽  
Multizone Model

Transport of solutes through diffusion is an important metabolic mechanism for the avascular cartilage tissue. Three types of interconnected physical phenomena, namely mechanical, electrical, and chemical, are all involved in the physics of transport in cartilage. In this study, we use a carefully designed experimental-computational setup to separate the effects of mechanical and chemical factors from those of electrical charges. Axial diffusion of a neutral solute (Iodixanol) into cartilage was monitored using calibrated microcomputed tomography (micro-CT) images for up to 48 hr. A biphasic-solute computational model was fitted to the experimental data to determine the diffusion coefficients of cartilage. Cartilage was modeled either using one single diffusion coefficient (single-zone model) or using three diffusion coefficients corresponding to superficial, middle, and deep cartilage zones (multizone model). It was observed that the single-zone model cannot capture the entire concentration-time curve and under-predicts the near-equilibrium concentration values, whereas the multizone model could very well match the experimental data. The diffusion coefficient of the superficial zone was found to be at least one order of magnitude larger than that of the middle zone. Since neutral solutes were used, glycosaminoglycan (GAG) content cannot be the primary reason behind such large differences between the diffusion coefficients of the different cartilage zones. It is therefore concluded that other features of the different cartilage zones such as water content and the organization (orientation) of collagen fibers may be enough to cause large differences in diffusion coefficients through the cartilage thickness.

scholarly journals The calculation of desalination of mineralized porous ice at thawing

2016 ◽  
Vol 56 (4) ◽  
pp. 545-554
Author(s):  
A. V. Sosnovsky ◽  
I. I. Kontorovich
Keyword(s):  
Diffusion Coefficient ◽  
Chemical Composition ◽  
Diffusion Coefficients ◽  
Drainage Water ◽  
Model Calculations ◽  
Ion Concentrations ◽  
Salt Ions ◽  
Mineralized Water ◽  
Mobility Of Ions ◽  
Order Of Magnitude

The results obtained in this work demonstrate that dynamics of desalination of porous ice depends on a mobility of ions of salts, and the mobility is determined by the diffusion coefficient. The ice was made by freezing of mineralized water of different chemical composition. Model calculations of average mineralization of the porous ice at its thawing were made, and the ion concentrations of different salts were defined. Values of the diffusion coefficients of the salt ions in the film of brine ice pellets were obtained by means of comparison of results of measurements and calculations of dynamics of content of the salt ions in a porous ice at its thawing. The diffusion coefficient of ions Na+, Cl−, SO4 2− is by order of magnitude larger than that of Ca2+ and by two orders of magnitudethan HCO3 −. This results in that the content of ions Na+, Cl−, SO42− decreases in porous ice at its thawing 3 times faster than the content of the ions Ca2+. Basing on analysis of chemical composition of drainage water in some regions in Russia a possibility to desalinate the porous ice formed during the winter sprinkling is demonstrated.

scholarly journals Are BVOC exchanges in agricultural ecosystems overestimated? Insights from fluxes measured in a maize field over a whole growing season

2016 ◽  
Author(s):  
A. Bachy ◽  
M. Aubinet ◽  
N. Schoon ◽  
C. Amelynck ◽  
B. Bodson ◽  
...  
Keyword(s):  
Western Europe ◽  
Growing Season ◽  
Bare Soil ◽  
High Variability ◽  
Agricultural Ecosystems ◽  
Maize Field ◽  
Volatile Organic ◽  
Order Of Magnitude ◽  
First Time ◽  
North Western

Abstract. Although maize is the second most important crop worldwide, and the most important C4 crop, no study on biogenic volatile organic compounds (BVOCs) has yet been conducted on this crop at ecosystem scale and over a whole growing season. This has led to large uncertainties in cropland BVOC emission estimations. This paper seeks to fill this gap by presenting, for the first time, BVOC fluxes measured in a maize field at ecosystem scale (using the disjunct eddy covariance by mass scanning technique) over a whole growing season in Belgium. The maize field emitted mainly methanol, although exchanges were bi-directional. The second most exchanged compound was acetic acid, which was taken up mainly in the growing season. Bi-directional exchanges of acetaldehyde, acetone and other oxygenated VOCs also occurred, whereas the terpenes, benzene and toluene exchanges were small, albeit significant. Surprinsingly, BVOC exchanges were as same order of magnitude on bare soil and on well developped vegetation, suggesting that soil is a major BVOC reservoir in agricultural ecosystems. Quantitatively, the maize BVOC emissions observed were lower than those reported in other maize, crops and grasses studies. The standard emission factors (SEFs) estimated in this study (231 ± 19 µgm−2h−1 for methanol, 8 ± 5 µgm−2h−1 for isoprene and 4 ± 6 µgm−2h−1 for monoterpenes) were also much lower than those currently used by models for C4 crops, particularly for terpenes. These results suggest that maize fields are small BVOC exchangers in north-western Europe, with a lower BVOC emission impact than that modelled for growing C4 crops in this in this part of the world. They also reveal the high variability in BVOC exchanges across world regions for maize and suggest that SEFs should be estimated for each region separately.

scholarly journals Are BVOC exchanges in agricultural ecosystems overestimated? Insights from fluxes measured in a maize field over a whole growing season

2016 ◽  
Vol 16 (8) ◽  
pp. 5343-5356 ◽  
Author(s):  
Aurélie Bachy ◽  
Marc Aubinet ◽  
Niels Schoon ◽  
Crist Amelynck ◽  
Bernard Bodson ◽  
...  
Keyword(s):  
Western Europe ◽  
Growing Season ◽  
Bare Soil ◽  
High Variability ◽  
Agricultural Ecosystems ◽  
Maize Field ◽  
Volatile Organic ◽  
Order Of Magnitude ◽  
First Time ◽  
North Western

Abstract. Although maize is the second most important crop worldwide, and the most important C4 crop, no study on biogenic volatile organic compounds (BVOCs) has yet been conducted on this crop at ecosystem scale and over a whole growing season. This has led to large uncertainties in cropland BVOC emission estimations. This paper seeks to fill this gap by presenting, for the first time, BVOC fluxes measured in a maize field at ecosystem scale (using the disjunct eddy covariance by mass scanning technique) over a whole growing season in Belgium. The maize field emitted mainly methanol, although exchanges were bi-directional. The second most exchanged compound was acetic acid, which was taken up mainly in the growing season. Bi-directional exchanges of acetaldehyde, acetone and other oxygenated VOCs also occurred, whereas the terpenes, benzene and toluene exchanges were small, albeit significant. Surprisingly, BVOC exchanges were of the same order of magnitude on bare soil and on well developed vegetation, suggesting that soil is a major BVOC reservoir in agricultural ecosystems. Quantitatively, the maize BVOC emissions observed were lower than those reported in other maize, crops and grasses studies. The standard emission factors (SEFs) estimated in this study (231 ± 19 µg m−2 h−1 for methanol, 8 ± 5 µg m−2 h−1 for isoprene and 4 ± 6 µg m−2 h−1 for monoterpenes) were also much lower than those currently used by models for C4 crops, particularly for terpenes. These results suggest that maize fields are small BVOC exchangers in north-western Europe, with a lower BVOC emission impact than that modelled for growing C4 crops in this part of the world. They also reveal the high variability in BVOC exchanges across world regions for maize and suggest that SEFs should be estimated for each region separately.

scholarly journals Effects of biogenic nitrate chemistry on the NO<sub>x</sub> lifetime in remote continental regions

2012 ◽  
Vol 12 (8) ◽  
pp. 20673-20716 ◽  
Author(s):  
E. C. Browne ◽  
R. C. Cohen
Keyword(s):  
Steady State ◽  
Organic Compound ◽  
Volatile Organic Compound ◽  
Transport Model ◽  
Chemical Transport ◽  
Organic Nitrate ◽  
Chemical Transport Model ◽  
Steady State Model ◽  
Volatile Organic ◽  
Order Of Magnitude

Abstract. We present an analysis of the NOx budget in conditions of low NOx (NOx = NO + NO2) chemistry and high biogenic volatile organic compound (BVOC) concentrations that are characteristic of most continental boundary layers. Using a steady-state model, we show that below 500 pptv of NOx, the NOx lifetime is extremely sensitive to organic nitrate (RONO2) formation rates. We find that even for RONO2 formation values that are an order of magnitude smaller than is typical for continental conditions significant reductions in NOx lifetime are caused by nitrate forming reactions. Comparison of the steady-state box model to a 3-D chemical transport model (CTM) confirms that the concepts illustrated by the simpler model are a useful approximation of predictions provided by the full CTM.

Pilot plant plasma-catalytic system for the decomposition of a volatile organic compound

2016 ◽  
Vol 15 (3) ◽  
pp. 251-259
Author(s):  
Shreedhar Devkota ◽  
◽  
Jin Oh Jo ◽  
Dong Lyong Jang ◽  
Young Jin Hyun ◽  
...  
Keyword(s):  
Organic Compound ◽  
Catalytic System ◽  
Volatile Organic Compound ◽  
Pilot Plant ◽  
Volatile Organic
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