Compilation and evaluation of gas phase diffusion coefficients of halogenated organic compounds

Organic halogens are of great environmental and climatic concern. In this work, we have compiled their gas phase diffusivities (pressure-normalized diffusion coefficients) in a variety of bath gases experimentally measured by previous studies. It is found that diffusivities estimated using Fuller's semi-empirical method agree very well with measured values for organic halogens. In addition, we find that at a given temperature and pressure, different molecules exhibit very similar mean free paths in the same bath gas, and then propose a method to estimate mean free paths in different bath gases. For example, the pressure-normalized mean free paths are estimated to be 90, 350, 90, 80, 120 nm atm in air (and N2/O2), He, argon, CO2 and CH4, respectively, with estimated errors of around ±25%. A generic method, which requires less input parameter than Fuller's method, is proposed to calculate gas phase diffusivities. We find that gas phase diffusivities in He (and air as well) calculated using our method show fairly good agreement with those measured experimentally and estimated using Fuller's method. Our method is particularly useful for the estimation of gas phase diffusivities when the trace gas contains atoms whose diffusion volumes are not known.


I
The diffusivity of CH3Cl in air at 298 K was measured by Cowie and Watts, [1] and the measured diffusivity is 10% larger than the estimated value.
Gotoh et al. measured the diffisitivities of CH3Cl in CH4 from 298 to 438 K, [2] and the differences between the measured and estimated diffusivities are <5% across the entire temperature range.
The diffusitivities of CH3Cl in SO2 and CH3OCH3, measured by Chakraborti and Gray, [3] are around 20% smaller than estimated values for temperatures in the range of 303 to 333 K. The diffusivity of CH3I in He, measured at 431 K by Fuller et al., [1] is only 1% smaller than the estimated value.
References: The diffusivity of CH2F2 in He, measured at 431 K by Fuller et al., [1] is 5% laregr than the estimated value.
References: The diffusivity of CH2Cl2 in He at 428 K, measured Fuller et al., [1] is 3% larger than the estimated value.
The diffusivities of CH2Cl2 in air, measured at 298 K by Cowie and Watts [2 ] and by Lugg [3] and from 288 to 308 K by Watts, [4] show excellent agreement with estimated values, with difference being 1% or smaller.
The diffusivities of CH2Cl2 in Kr, measured by Singh and Srivastava from 278 to 318 K, [5] are 15% to 17% smaller than the estimated values. The measured diffusivity of CH2ClBr in air at 298 K [1] is 10% smaller than the estimated value. The measured diffusivity of CH2Br2 in He at 428 K [1] is 8% smaller than the estimated value.

References
References: The diffusivity of CHCl3 in He at 429 K, measured by Fuller et al., [1] is 2% smaller than the estimated value.
Nagata and Hasegawa investigated the temperature dependence of diffusivities of CHCl3 in N2 from 361 to 418 K, [2] and differences between the measured and estimated values are not larger than 3%.
Nagata and Hasegawa measured the diffusivities of CHCl3 in CO2 at 363, 383, and 404 K. [2] The differences between the measured and estimated diffusivities are around 10% or smaller.
Srivastava and Saran measured the diffusivities of CHCl3 in Kr at 284, 293, 303, and 313 K, [8] and the measured diffusivities are around 13% smaller than the estimated values.
The diffusivity of CHCl3 in C2H5OC2H5 at 293 K, measured by Weissman, [9] is 25% smaller than the estimated value.
References:  The measured diffusivity of CHBr3 in air at 298 K [1] is 18% smaller than the estimated value.
Briks et al. [3] measurd the diffusivities of CF2Cl2 in di-n-butyl phthalate at 293 and 303 K, and the measured diffusivities are 29% and 26% smaller than the measured values. Mueller and Cahill [1] measured the diffusivities of CF4 in CH4 from 298-383 K, and the differences between the measured and estimated diffusivities are around 8% or smaller.
Raw and Tang [2] measured the diffusivities of CF4 in SF6 from 303 to 342 K, and the differences between the measured and estimated diffusivities are around 12%.
Wilhelm and Battino [3] measured the diffusivities of CF4 in n-haxane from 283 to 328 K, and the measuered diffusivities are 11% to 15% larger than the estimated values.
Wilhelm et al. [4] measured the diffusivities of CF4 in cyclohaxane from 283 to 343 K, and the measured diffusivities are ~15% larger than the estimated values.
The diffusivities of CF4 in benzene are measuered by Wilhelm from 283 to 343 K, [4] and the differences between the measured and estimated diffusivities are around 15% or smaller.
Wilhelm and Battino [3] measured the diffusivities of CF4 in n-heptane from 283 to 343 K, and the differences between the measured and estimated diffusivities are 17% or smaller.
Wilhelm et al. [4] measured the diffusivities of CF4 in methylcyclohexane from 283 to 343 K, and the measured diffusivities are 5% to 14% larger than the estimated values.
Wilhelm et al. [4] measured the diffusivities of CF4 in toluene from 283 to 343 K, and the differences between the measured and estimated values are 14% or smaller.
15 Wilhelm and Battino [3] measured the diffusivities of CF4 in octane from 283 to 343 K, and the difference between the measured and estimated diffusivities are 19% or smaller. The diffusivities of CCl4 in N2 were measured by Nagata and Hasegawa [1] from 364 to 423 K and by Arinikar [2] at 353 K. The measured diffusivities are 2% to 6% smaller than the estimated values.
Five studies measured the diffusivities of CCl4 in air at 295-298 K, [3,4,[6][7][8] and the differences between the measured and estimated diffusivities are 7% or smaller. Getzinger and Wilke [5] and Richardson [9] measured the diffusivities of CCl4 in air at 308 and 313 K, and the differences between the measured and estimated values are 4% or smaller. The temperature dependence of diffusivities of CCl4 in air was investigated from 298 to 348 K by Watts. [7] The differences between the measured and estimated diffusivities are 5% or smaller across the entire temperature range investigated.
Nagata and Hasegawa [1] measured the diffusivities of CCl4 in CO2 from 363 to 423 K, and the measured diffusivities are around 6% smaller than the estimated values.
Weissman [10] measured the diffusivity of CCl4 in benzene at 293 K, and the measured diffusivity is 12% larger than the estimated value.
Weissman [10] measured the diffusivities of CCl4 in CH2Cl2 at 293, 353, and 413 K, and the measured diffusivities are all around 25% smaller than estimated values.
The diffusivity of CCl4 in CHCl3 was measured by Weissman at 293 K, [10] and the measured diffusivity is 17% smaller than the estimated value. The measured diffusivities in air are 9% larger than the estimated value for CCl2O and 1% larger for CNCl. [1] Two studies measured the diffusivities of CCl3NO2 in air at 298 K, and the measured values are 7% larger [1] and 2% smaller [2] than the estimated ones. Gotoh et al. [1] measured the diffusivities in CH3Cl from 298 to 438 K, and the differences between the measured and estimated diffusivities are around 22% or less.
The diffusivities of CH3CH2Cl in Kr were measured from 275 to 318 K by Singh and Srivastava, [2] and the differences between the measured and estimated diffusivitiies are smaller than 10%.
Lugg [2] and Grob and Elwakil [3] measurd the diffusivities of CH3CH2Br in air at around room temperature, and the differences between measured and estimated diffusivities are 4% to 6%. The average diffusivity of CH3CH2I in air at 295 K, measured by Grob and Elwakil, [1] is ~3% larger then the estimated value.
The diffusivity of CH3CH2I in He at 428 K, measured by Fuller et al., [2] is 3% smaller than the estimated value. The diffusivity in He at 430 K, measured by Fuller et al., [1] is 9% larger than the estimated value.
The diffusivities of CH2ClCH2Cl in air were measured by two studies at around room temperature, [2,3] and the differences between the measured and estimated values are 4% or less.
References:  The diffusivity of CH2BrCH2Br in air at 298 K, measured by Lugg, [1] is 13% smaller than the estimated value.
References: Barr and Watts [1] measured the diffusivities of CH2=CHCl and CHCl=CHCl in air at 298 K, and Lugg [2] measured the diffusivities of CHCl=CCl2 and CCl2=CCl2 in air at 298 K. The measured diffusivities are all 2% smaller than the estimated values. The measured diffusivity of CH3CH2CH2Cl in He at 428 K [1] is only 1% larger than the estimated value.
The measured diffusivities of CH3CH2CH2Br in He at 428 K [1] and in air at 298 K [2] are 5% and 8% smaller than the estimated values, respectively.
The measured diffusivities of CH3CHBrCH3 in He at 428 K [1] and in air at 298 K [2] are 3% and 4% smaller than the estimated values, respectively. The measured diffusivities of CH3CH2CH2I in He at 430 K, [1] in H2 at 303 K, [2] in N2 at 303 K, [2] and in air at 298 K [3] are 2% smaller, 13% smaller, 11% smaller, and 5% larger than the estimated values.
The measured diffusivities of CH3CHICH3 in He at 430 K [1] and in air at 298 K [3] are 2% smaller and 6% larger than the estimated values. The measured diffusivities in air at 298 K [1] are 3% smaller than the estimated value for CH3CHCH2Cl, 9% smaller for CH3CHBrCH2Cl, and 2% larger for CH2=CHCH2Cl, respectively.

CH3CHClCH2Cl, CH3CHBrCH2Cl, CH3BrCHBrCH2Cl, and CH2=CHCH2Cl
The measured diffusivity of CH3CHBrCH2Cl in He at 427 K [2] is 2% larger than the estimated value. The differences between the measured and estimated diffusivities in He at 429 K are around 1% for both 1-chlorobutane and 2-chlorobutane. [1] The average measured diffusivity of 1-chlorobutane in air at 296 K [2] is 8% larger than the estimated value. The measured diffusivities of 1-bromobutane in He at 427 K, [1] in H2 at 303 K, [2] and in N2 at 303 K [2] are 2%, 10%, and 10% smaller than the estimated values.

1-bromobutane and 2-bromobutane
The difference between the measured [1] and estimated diffusivities of 2-bromobutane in He at 427 K is less than 1%. The differences between the measured and estimated diffusivities are 1% for 1-iodobutane in He at 428 K, [1] 3% for 2-iodobutane in He at 427 K, [1] and 5% for dichloroethyl ether in air at 298 K, [2] respectively. Fuller et al. [1] measured the diffusivities of 1-fluorohexane, 1-bromohexane, 2-bromohexane, and 3bromohexane in He at ~430 K. The differences between the measured and estimated diffusivities are around 1% for all the four compounds.

1-iodobutane, 2-iodobutane, and dichloroethyl ether
The diffusivity of fluorobenzene in He at 430 K was measured by Fuller et al., [1] and the measured diffusivity is 9% larger than the estimated value.
The diffusivity of fluorobenzene in H2 at 303 K was measured by Byrne et al., [2] and the measured diffusivity is 9% larger than the estimated value.
The diffusivity of fluorobenzene in Ar at 303 K was measured by Byrne et al., [2] and the measured diffusivity is 10% larger than the estimated value.
The diffusivity of fluorobenzene in N2 at 303 K, measured by Byrne et al., [2] is 11% larger than the estimated value.
The average diffusivity of fluorobenzene in N2 at 295 K, measured by Grob and Elwakil, [3] is ~5% larger than the estimated value.
Fuller et al. [1] measured the diffusivity of chlorobenzene in He, and the measured diffusivity is 7% larger than the estimated value.
The diffusivities of chlorobenzene in air were measured by two studies. [4,5] The diffusivities from 299 to 332 K, measured by Gilliland, [4] are around 3% (or less) smaller than the estimated values, and the diffusivity at 298 K, measured by Lugg, [5] is only 1% smaller than the estimated value.

39
The diffusivity of bromobenzene in He, measured by Fuller et al., [1] is 9% larger than the estimated value. The diffusivity of hexafluorobenzene in He at 429 K, measured by Fuller et al., [1] is 10% larger than the estimated value.