Determination of partition and diffusion coefficients of formaldehyde in selected building materials and impact of relative humidity

2012 ◽  
Vol 62 (6) ◽  
pp. 671-679 ◽  
Author(s):  
Jing Xu ◽  
Jianshun S. Zhang ◽  
Xiaoyu Liu ◽  
Zhi Gao
Keyword(s):  
Relative Humidity ◽  
Diffusion Coefficients ◽  
Building Materials ◽  
And Diffusion

scholarly journals Relative humidity-dependent viscosity of secondary organic material from toluene photo-oxidation and possible implications for organic particulate matter over megacities

2016 ◽  
Author(s):  
M. Song ◽  
P. F. Liu ◽  
S. J. Hanna ◽  
R. A. Zaveri ◽  
K. Potter ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Relative Humidity ◽  
Diffusion Coefficients ◽  
Organic Material ◽  
Organic Molecules ◽  
Mixing Times ◽  
Organic Particulate Matter ◽  
Photo Oxidation ◽  
Diffusion Rates ◽  
And Diffusion

Abstract. To improve predictions of air quality, visibility, and climate change, knowledge of the viscosities and diffusion rates within organic particulate matter consisting of secondary organic material (SOM) is required.Most qualitative and quantitative measurements of viscosity and diffusion rates within organic particulate matter have focused on SOM particles generated from biogenic VOCs such as α-pinene and isoprene. In this study, we quantify the relative humidity (RH)-dependent viscosities at 295 ± 1 K of SOM produced by photo-oxidation of toluene, an anthropogenic VOC. The viscosities of toluene-derived SOM were 2 × 10−1 to ∼6 × 106 Pa·s from 30 to 90 % RH, and greater than ~2 × 108 Pa·s (similar to or greater than the viscosity of tar pitch) for RH ≤ 17 %. These viscosities correspond to Stokes-Einstein-equivalent diffusion coefficients for large organic molecules of ~2 × 10−15 cm2·s−1 for 30 % RH, and lower than ~3 × 10−17 cm2·s−1 for RH ≤ 17 %. Based on these estimated diffusion coefficients, the mixing time of large organic molecules within 200 nm toluene-derived SOM particles is 0.1–5 hr for 30 % RH, and higher than ~100 hr for RH ≤ 17 %. These results were used, as a first-order approximation, to estimate if organic particulate matter will be in well-mixed over the world's top 15 most populous megacities. If the organic particulate matter in the megacities is similar to the toluene-derived SOM in this study, in Kolkata, Istanbul, Dhaka, Tokyo, Shanghai, and Mumbai, mixing times in organic particulate matter during extended periods of the year will be very short, and well-mixed particles can be assumed. On the other hand, the mixing times of large organic molecules in organic particulate matter in Delhi, Beijing, Mexico City, Cairo, and Karachi may be long and the particles may not be well-mixed in the afternoon (3:00–5:00 local time) during certain times of the year.

Determination of mobility and diffusion coefficients of Ar+ and Ar2+ ions in argon gas

2020 ◽  
Vol 23 (2) ◽  
pp. 143-151
Author(s):  
Jamiyanaa Dashdorj ◽  
William C. Pfalzgraff ◽  
Aaron Trout ◽  
Delenn Fingerlow ◽  
Michelle Cordier ◽  
...  
Keyword(s):  
Diffusion Coefficients ◽  
Argon Gas ◽  
And Diffusion

scholarly journals Determination of Diffusion Coefficients of Selected Long Chain Hydrocarbons using Reversed- Flow Gas Chromatographic Technique

2011 ◽  
Vol 8 (4) ◽  
pp. 1916-1924 ◽  
Author(s):  
Khalisanni Khalid ◽  
Rashid Atta Khan ◽  
Sharifuddin Mohd Zain
Keyword(s):  
Gas Chromatography ◽  
Diffusion Coefficients ◽  
Elution Curve ◽  
Mathematical Expression ◽  
Chromatographic Technique ◽  
Reversed Flow ◽  
Future Studies ◽  
And Diffusion ◽  
Long Chain

The reversed-flow gas chromatography (RF-GC) technique was used to study the evaporation rate and estimating the diffusion coefficient of samples. The RF-GC system comprises of six-port valve, sampling and diffusion column, detector and modified commercial gas chromatography machine. Selected long chain of hydrocarbons (99.99% purity) was used as samples. The solute (stationary phase) were carried out by carrier gas (mobile phase) to the detector. The data obtained from the RF-GC analysis were analysed by deriving the elution curve of the sample peaks using mathematical expression to find the diffusion coefficients values of respective liquids. The values obtained were compared with theoretical values to ensure the accuracy of readings. The interesting findings of the research showed the theoretical values of equilibrium at liquid-gas interphase lead to profound an agreement with the experimental evidence, which contributes for the references of future studies.

Site Preference and Diffusion in Ni3Al Alloyed with Ir, Ta or Re at 1200°C

2010 ◽  
Vol 297-301 ◽  
pp. 1322-1327 ◽  
Author(s):  
N. Garimella ◽  
H.J. Choi ◽  
Yong Ho Sohn
Keyword(s):  
Diffusion Coefficients ◽  
Tracer Diffusion ◽  
Site Preference ◽  
Solid Diffusion ◽  
Ordered Intermetallic ◽  
Ternary Alloying ◽  
Tracer Diffusion Coefficients ◽  
Interdiffusion Coefficients ◽  
And Diffusion

Diffusion in L12-Ni3Al with ternary alloying additions of Ir, Ta and Re was investigated at 1200°C using solid-to-solid diffusion couples, and examined with respect to site preference in ordered intermetallic compound. In addition to determination of average ternary interdiffusion coefficients [1-3], average effective interdiffusion coefficients were determined directly from the experimental concentration profiles. Ni has the largest magnitude of average effective interdiffusion coefficient, followed by Al, Ir, Re and Ta. The average effective interdiffusion coefficients for Ir, Re and Ta are much smaller than those for Ni and Al. Tracer diffusion coefficients determined by extrapolation technique, and available literature also followed the same trend. The relative tendency of Ni, Al, Ir, Re and Ta to occupy the -Ni and -Al sites are correlated to these diffusion coefficients, with due consideration for diffusion mechanisms and coordination of atoms.

scholarly journals Relative humidity-dependent viscosity of secondary organic material from toluene photo-oxidation and possible implications for organic particulate matter over megacities

2016 ◽  
Vol 16 (14) ◽  
pp. 8817-8830 ◽  
Author(s):  
Mijung Song ◽  
Pengfei F. Liu ◽  
Sarah J. Hanna ◽  
Rahul A. Zaveri ◽  
Katie Potter ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Relative Humidity ◽  
Diffusion Coefficients ◽  
Organic Material ◽  
Organic Molecules ◽  
Mixing Times ◽  
Organic Particulate Matter ◽  
Photo Oxidation ◽  
Diffusion Rates ◽  
And Diffusion

Abstract. To improve predictions of air quality, visibility, and climate change, knowledge of the viscosities and diffusion rates within organic particulate matter consisting of secondary organic material (SOM) is required. Most qualitative and quantitative measurements of viscosity and diffusion rates within organic particulate matter have focused on SOM particles generated from biogenic volatile organic compounds (VOCs) such as α-pinene and isoprene. In this study, we quantify the relative humidity (RH)-dependent viscosities at 295 ± 1 K of SOM produced by photo-oxidation of toluene, an anthropogenic VOC. The viscosities of toluene-derived SOM were 2  ×  10−1 to  ∼  6  ×  106 Pa s from 30 to 90 % RH, and greater than  ∼  2  ×  108 Pa s (similar to or greater than the viscosity of tar pitch) for RH  ≤  17 %. These viscosities correspond to Stokes–Einstein-equivalent diffusion coefficients for large organic molecules of  ∼  2  ×  10−15 cm2 s−1 for 30 % RH, and lower than  ∼  3  ×  10−17 cm2 s−1 for RH  ≤  17 %. Based on these estimated diffusion coefficients, the mixing time of large organic molecules within 200 nm toluene-derived SOM particles is 0.1–5 h for 30 % RH, and higher than  ∼  100 h for RH  ≤  17 %. As a starting point for understanding the mixing times of large organic molecules in organic particulate matter over cities, we applied the mixing times determined for toluene-derived SOM particles to the world's top 15 most populous megacities. If the organic particulate matter in these megacities is similar to the toluene-derived SOM in this study, in Istanbul, Tokyo, Shanghai, and São Paulo, mixing times in organic particulate matter during certain periods of the year may be very short, and the particles may be well-mixed. On the other hand, the mixing times of large organic molecules in organic particulate matter in Beijing, Mexico City, Cairo, and Karachi may be long and the particles may not be well-mixed in the afternoon (15:00–17:00 LT) during certain times of the year.

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