Lifetimes of Fluorinated Compounds


Free download. Book file PDF easily for everyone and every device. You can download and read online Lifetimes of Fluorinated Compounds file PDF Book only if you are registered here. And also you can download or read online all Book PDF file that related with Lifetimes of Fluorinated Compounds book. Happy reading Lifetimes of Fluorinated Compounds Bookeveryone. Download file Free Book PDF Lifetimes of Fluorinated Compounds at Complete PDF Library. This Book have some digital formats such us :paperbook, ebook, kindle, epub, fb2 and another formats. Here is The CompletePDF Book Library. It's free to register here to get Book file PDF Lifetimes of Fluorinated Compounds Pocket Guide.
Main navigation

Schematic diagram of discharge flow reactor. Therefore, we purified the samples by means of gas chromatography. Figure 3 shows a schematic diagram of the sample purification apparatus. An evacuated sampling tube 10—25 cm3 inner volume was charged with the sample gas or vapor through an electromagnetic valve V3 and then introduced into a stainless steel column 7. For many of the samples, a column packed with Silicone DC Shimadzu was used.

Nitrogen was used as the carrier gas. The middle fraction of the main peak was collected through a four-way switching cock V2 into a trap cooled with liquid nitrogen at the timing shown in a example of chromatograph of Figure 3. The switching cock V1 and the electromagnetic valves V3 and V4 were operated by a valve controller according to the predetermined interval, and the switching cock V2 was operated at timing that depended on the retention time of the main peak. During a purification, the sampling tube was evacuated with a pump through a electromagnetic valve V4 , and new sample was introduced into the tube for the next cycle through a valve V3.

This procedure was automatically repeated hundreds of times to collect sufficient amounts of the purified sample. For purification of liquid samples, the sample was supplied to the column by an autoinjector Shimadzu, AOC i instead of the sampling tube and V1. The purification rate was approximately a few cubic centimeters purified liquid base per day at most. The actual purification rate depended on such factors as the purity of the original sample, the required purity level of the purified sample, the retention times of the impurity peaks relative to the retention time of the main peak, the sample vapor pressure, and so on.

The yield of the purified sample was approximately one-quarter of the original sample. Because the impurity level of the material collected in trap T2 was only slightly higher than that of the original sample, the material 11 Experimental Apparatus and Methods collected in traps T2 and T3 could be used in the purification cycle again. To obtain an amount of sample that was sufficient for measuring the temperature dependence of the reaction rate by means of several techniques, the purification process had to be carried out continuously for at least a month.

Schematic diagram of sample purification apparatus. The purities of the purified samples and the original samples were determined by using a gas chromatograph with an FID detector, and the integrated intensity of the main peak relative to the total area was taken as the sample purity. Usually, the samples were analyzed with a stainless steel column packed with Silicone DC 3 mm i.

The lowest of the values obtained with the various columns was taken as the sample purity. Equation 3.

Greenhouse Gases: How Long Will They Last?

Loss processes include diffusion, heterogeneous wall reactions, and reactions with trace impurities in the carrier gas. If the initial concentration of OH radicals is less than about molecule cm—3, the effect of reaction of OH radicals with reaction products can be ignored. Because the concentration of the target compound is on the order of — molecule cm—3, the reaction conditions are clearly pseudo-first-order, and the changes in the concentration of the target compound during the reaction can be ignored.

From Equations 3. As is apparent from Equation 3. Therefore, an accurate rate constant can be obtained directly. However, if the target compound contains reactive impurities such as unsaturated compounds, the reaction of OH radicals with the impurities reduces the OH radical concentration. Therefore, high-purity samples must be used to avoid the influence of reactive impurities.

The plotted points are distributed along a straight line, and the bimolecular rate constant for the reaction of OH radicals with HFC can be derived from the slope by the linear least-squares fit to the observed data. In the case of the FP and LP methods, the small intercept observed when there is no target compound kd is mainly caused by diffusion of OH radicals from the viewing zone, and partially caused by reaction of OH radicals with impurities contained in the gas mixture. Thus, the origins of kd and kw depend on the experimental conditions.


  • California Air Resources Board!
  • Lifetimes of Fluorinated Compounds.
  • Raw materials, Intermediates & Active ingredients.
  • INFONA - science communication portal.
  • Herbal Tonic Therapies.
  • Journal list menu.
  • Along the Way: The Journey of a Father and Son.

To ensure that there were no unexpected errors, the experiments were repeated at intervals ranging from several days to a few months under a variety of experimental conditions; the following parameters were varied: linear flow velocity of the gas mixture, total pressure, H2O concentration FP method , H2O and N2O concentrations LP-H2O method , H2O2 concentration LP-H2O2 method , energy of flash lamp or excimer laser FP or LP methods , and NO2 and H2 concentrations DF method. For each reaction temperature and method, the experiments were typically repeated six times, and the results are summarized in plots like the one shown in Figure 6.

All the plots give linear relationships with relatively small scatters. Plot of the observed pseudo-first-order rate constant kobs against HFC concentration. Plot of the pseudo-first-order rate constants corrected for wall loss, kobs-kd, against HFC concentration. FP-LIF method. Both traces were recorded at the same sensitivity, and the actual height of the main peak is around times as high as the height shown in the figure.

In the original sample, there were two large impurity peaks before the main peak and a few additional small peaks before and after the main peak. The impurities were not identified. After purification, the intensities of the two main impurity peaks were drastically reduced, and the smaller peaks disappeared. The purities were estimated to be Thus, the impurity level of the sample was reduced by about two orders of magnitude by a single purification process. Analytical results of HCFCb. To examine the adequacy of this purification method for kinetic measurements, we prepared samples with different purity levels by the GC method and subjected them to kinetic measurements.


  • Users Guide.
  • Atmospheric lifetimes of selected fluorinated ether compounds.
  • Flame Hardening?
  • Organic Fluorinated Compounds.

The systematic errors are not contained here. The solid line in this figure represents the result of the linear least-squares fit to the measured rate constants versus impurity concentration. The rate constant for the original sample As can be seen in the figure, the apparent rate constant decreases as the impurity level decreases and almost reaches a constant value when the impurity level falls below about 0. By extrapolating to an impurity level of zero, we obtained a rate constant of 3. From the values of the measured rate constant, we estimated the influence of the impurities to be Figure 8.

Results of Kinetic Measurements 19 If the sum total of impurities removed from the original sample was responsible for the decrease in the observed rate constant, the corresponding rate constant for reaction of the impurities with OH radicals would be 8. The estimated rate constant for the impurities contained in the original sample indicates that their influence on the measured rate constants can be no larger than 8. Therefore, we concluded that the effects of any remaining impurities in the purified HCFCb sample can be neglected and that the GC purification method is adequate for kinetic measurements.

At lower temperatures, however, because reactive impurities can strongly affect the rate constant measurement if their activation energies are low, purified samples were used for measurements of the temperature dependence of the rate constants. The purities of the original and purified samples used in the measurements are listed in Table 1 together with the measured rate constants obtained by various methods at K.

Experiments were usually repeated at least six times 40—60 measurements of OH radical decay at a given temperature for each experimental method. In all cases, the OH radical decay showed exponential behavior, and the linearity and scatter of the plotted points for individual experiments were much the same as those shown in Figure 4. In addition, the linearity and scatter of the plotted points for the pseudo-first-order rate constants versus the concentration of the target compound for individual experiments were much the same as those shown in Figures 5 and 6.

In these tables, the concentration ranges for the HCFC or HFC sixth column represent the minimum and maximum concentrations during repeated experiments. Table 1. The Arrhenius rate parameters and the room temperature rate constants obtained in the present study are summarized in oddnumbered tables from 3 to Results reported by other groups are also shown in these figures and tables. The recommended rate expressions and the room temperature rate constants based on the present work and on values reported by other groups, if available, are also listed in odd-numbered tables from 3 to In deriving the recommendations, we considered the rate constants in the temperature range — K.

Table 2. The purity of the sample used in the measurement was Therefore, we concluded that the effect of any impurities remaining in the purified samples was negligible. Figure 9 shows the Arrhenius plots. Table 3 summarizes the room temperature rate constants and Arrhenius parameters obtained in this study as well as values reported by other groups. The results of Hsu and DeMore [14] and Cavalli et al. The frequency factor and temperature dependence reported by Clyne and Holt [16] are considerably larger than ours.

Table 3. The results of other groups agree reasonably well with the present results. The recommended rate expression listed in Table 3 was derived from the present results; those of Orkin and Khamaganov [18], Atkinson et al. From the purity and the measured rate constants, the influence of impurities was estimated to be 0. The Arrhenius plots and rate parameters measured in this work and reported by other groups are shown in Figure 10 and Table 5. The results reported by Clyne and Holt [16], Nielsen [26], and Brown et al. Watson et al. As is apparent in Figure 10, the results of Watson et al.

At higher temperature, the results of Yamada et al. Table 4. Table 5. In contrast, at lower temperature, the results of Gierczak et al. However, these two results agree with ours in the middle temperature range about room temperature to K. The recommended rate expression was derived from the present results; the results of Liu et al. The difference between our temperature dependence and that of JPL seems to be due to the difference in the temperature ranges considered. Thus, the effect of any impurities remaining in the purified sample seems to be negligible.

Table 6. The Arrhenius plots are shown in Figure 11, and the Arrhenius rate parameters are summarized in Table 7. Table 7. The only available published data are those of Orkin and Khamaganov [18], which are also shown in Figure 11 and Table 7. The recommended rate expression was derived from this work and that of Orkin and Khamaganov [18]. Figure The Arrhenius plots and rate parameters together with results published by other groups are shown in Figure 12 and Table 9.

The recommended rate expression was derived from the present results and those of Gierczak et al. DeMore [14]. Table 8. Experimental conditions and results for measurements of OH radicals with HCFC temperature, k, , technique K cm3 molecule-1 s-1 t,sa no. Table 9.

Suggested Additional Reading:

If the sum total of impurities removed from the original sample is responsible for the decreases in the observed rate constants, the rate constant for the impurities is 1. The estimated rate constant for the impurities in the original sample indicates that their influence on the measured rate constants can be no larger than 1. Figure 13 shows the Arrhenius plots. Table 11 summarizes the room temperature rate constants and the Arrhenius parameters obtained in this study as well as values reported by other groups [29, 33, 34].

Fang et al. Our result at K derived from the Arrhenius parameters is 1. This value is in excellent agreement with the values of Watson et al. The rate constant at K reported by Jeong et al. The recommended rate expression was derived from the present results and those of Watson et al.

Table The rate constants for reaction of HCFCa with OH radicals and the experimental conditions for individual measurements over the temperature range — K are summarized in Table Figure 14 and Table 13 show the present results and the values reported by other groups. The results reported by Fang et al. The frequency factor and temperature dependence reported by Clyne and Holt [16] are very different from those reported by other groups.

The recommended rate expression was derived from the present results; those of Fang et al. From the purity and the measured rate constants of the purified sample, the influence of impurities was estimated to be 2. The results of our measurements and the experimental conditions are listed in Table The results are plotted in Figure 15 and summarized in Table Therefore, the recommended rate expression is that derived from the present results. If the sum total of impurities removed from the original sample is responsible for the decreases in the observed rate constants, the rate constant for reaction of the impurities with OH radicals is 8.

If the rate constant for the impurities is as large as 8. Talukdar et al. Figure 16 and Table 17 show the present results and the values reported by other groups. In Figure 16 and Table 17, the results of Huder and DeMore [36] are the unit-weighted averaged values obtained with these two 43 Results of Kinetic Measurements reference compounds. The room temperature rate constant reported by Brown et al. The results of Liu et al. The recommended rate expression was derived from the present results; those of Zhang et al. However, when the purified sample was used for the kinetic measurements, the rate constants were not affected by the reactive impurities.

Table 18 summarizes our experimental conditions and results. The Arrhenius plots and rate parameters are shown in Figure 17 and Table 19, along with literature data.


  • Contact Us!
  • GHG Short-Lived Climate Pollutant Inventory | California Air Resources Board;
  • Mind Change: How Digital Technologies Are Leaving Their Mark on Our Brains.
  • Toxicology of perfluorinated compounds;
  • How to Buy and Sell Real Estate for Financial Freedom: Dozens of Strategies to Fix, Flip, Rent, and Sell Your Way to Real Estate Riches.
  • Atmospheric lifetimes of selected fluorinated ether compounds.

At K, the rate constant reported by Clyne and Holt [16] is about 2 times as large as ours. The frequency factor and temperature dependence reported by Brown et al. Experimental conditions and results for measurements of OH radicals with HCFCb technique k, , t , s or cm3 molecule-1 s-1 U, m s-1 a pressure, torr no. The purity of the sample used in the measurement was higher than The recommended rate expression was derived from the present results; the results of Handwerk and Zellner [23], Watson et al. From the purity and the measured rate constants, the influence of the impurities on the rate constants of the purified sample was estimated to be 0.

The measurement results and experimental conditions are listed in Table The results are plotted in Figure 18 and summarized in Table From the purity and the measured rate constants, the influence of impurities was estimated to be 1. The results are plotted in Figure 19 and summarized in Table Experimental conditions and results for measurements of OH radicals with HCFCfb temperature, k, t , s or technique K cm3 molecule-1 s-1 U, m s-1 a no.

From the purity and the measured rate constants, the influence of impurities was estimated to be 9. Table 24 summarizes our experimental conditions and the results for reaction of OH radicals with HFC Figure 20 and Table 25 show the present results and the values reported by other groups. The frequency factor and temperature dependence reported by Clyne and Holt [16] are considerably larger than those of 52 Kazuaki Tokuhashi, Liang Chen, Kenji Takizawa et al. In the middle temperature range, the results of Jeong and Kaufman [22] are close to ours, whereas their values are larger than ours at higher temperature.

The recommended rate expression was derived from the present results; those of Talukdar et al. The rate constants for reaction of HFC with OH radicals and the experimental conditions used for individual measurements in the present study are summarized in Table The Arrhenius plots obtained in this work as well as values reported by other groups are plotted in Figure 21 and summarized in Table In Figure 21 and Table 27, the results of DeMore [44] are the unit-weighted averaged values obtained with these two reference compounds.

The room temperature rate constants of Clyne and Holt [16] and Brown et al. The present results agree with those of Talukdar et al. The recommended rate expression was derived from the present work and the results of Talukdar et al.

Naturally Occurring Organic Fluorine Compounds

Experimental conditions and results for measurements of OH radicals with HFCa technique k, , cm3 molecule-1 s-1 t , s or U, m s-1 a pressure, torr [HFCa], molecule cm-3 no. Results of Kinetic Measurements 59 2. If the sum total of the impurities removed from the original sample is responsible for the decreases in the observed rate constants, the rate constant for the impurities is 4.

From the estimated rate constant for the impurities contained in the original sample, their influence on the measured rate constants of 60 Kazuaki Tokuhashi, Liang Chen, Kenji Takizawa et al. Table 28 summarizes our experimental conditions and the results for reaction of HFCa with OH radicals. The Arrhenius plots and rate parameters are shown in Figure 22 and Table 29, together with literature data.

In Figure 22 and Table 29, the results of DeMore [44] are the unit-weighted averaged values obtained with these four reference compounds. The recommended rate expression was derived from the present results; those of Leu and Lee [46], Liu et al. The rate constants for reaction of HFC with OH radicals and the experimental conditions for individual measurements over the temperature range — K measured by means of the various methods are summarized in Table The Arrhenius plots and rate parameters obtained in this work as well as kinetic data reported by other groups are shown in Figure 23 and summarized in Table The result of Barry et al.

The room temperature rate constant reported by Clyne and Holt [16] is 2. In contrast, the present value agrees well with those of the relative rate study by Barry et al. In addition, the room temperature rate constant reported by Martin and Paraskevopoulos [45] is very close to our value. The recommended rate expression was derived from the present study, the results of Barry et al. Experimental conditions and results for measurements of OH radicals with HFC technique k, , cm3 molecule-1 s-1 t , s or U, m s-1 a pressure, torr [HFC], molecule cm-3 no.

Results of Kinetic Measurements 65 k , cm3 molecule-1 s-1 5. From the purity and the measured rate constants, the influence of impurities was estimated to be smaller than 0. The rate constants for reaction of HFCa with OH radicals and the experimental conditions are summarized in Table The Arrhenius plots and rate parameters measured in this work and values reported by other groups are shown in Figure 24 and listed in Table The frequency factor and temperature dependence reported by Nielsen [26] are slightly larger than ours, whereas those of Brown et al.

The rate constants of Clyne and Holt [16] are larger than ours over the entire temperature range. The recommended rate expression was derived from the present results; those of Gierczak et al. If, however, the sum total of impurities removed from the original sample is responsible for the decreases in the observed rate constants, the rate constant for the impurities is 2. If the rate constant for reaction of impurities remaining in the purified sample is as large as 2. The rate constants and the experimental conditions for reaction of OH radicals with HFCea are summarized in Table The Arrhenius plots and rate parameters obtained in this work as well as kinetic data reported by other groups are shown in Figure 25 and summarized in Table The results of Hsu and DeMore [14] obtained by the relative rate method were recalculated on the basis of the value recommended by JPL [2] for reference reaction of OH radicals with CH4.

As shown in Figure 25, the present results agree with those of Nelson et al. The room temperature rate constants of Garland et al. The recommended rate expression was derived from the present results and those of Nelson et al. Experimental conditions and results for measurements of OH radicals with HFCea k, ,cm3 molecule-1 s-1 t,sa pressure, torr [HFCea], molecule cm-3 no. Summary of the rate constants for the reaction of OH radicals with HFCea A a, cm3 molecule-1 s-1 k a, cm3 molecule-1 s-1 T range, K technique b reference 5.

If, however, the sum total of impurities removed from the original sample is responsible for the decreases in the observed rate constants, the rate constant for reaction of the impurities with OH radicals is 1. From the estimated rate constant for impurities contained in the original sample, their influence on the measured rate constants can be no larger than 0.

Table 36 summarizes our experimental conditions and results for reaction of OH radicals with HFCca. The Arrhenius plots and rate parameters are shown in Figure 26 and Table 37, together with results reported by other groups. Experimental conditions and results for measurements of OH radicals with HFCca k, , cm3 molecule-1 s-1 t,sa pressure, torr [HFCca], molecule cm-3 no. The temperature dependencies of the present results and the results of two other groups agree with one another, and the results of Zhang et al. Our results are in excellent agreement with those of Hsu and DeMore [14] over the entire temperature range.

The recommended rate expression was derived from the present results and those of Hsu and DeMore [14]. If you previously purchased this article, Log in to Readcube. Log out of Readcube. Click on an option below to access. Log out of ReadCube. Volume , Issue D1. If you do not receive an email within 10 minutes, your email address may not be registered, and you may need to create a new Wiley Online Library account.

If the address matches an existing account you will receive an email with instructions to retrieve your username. Open access. Robert A. Morris Search for more papers by this author. Thomas M. Miller Search for more papers by this author. Viggiano Search for more papers by this author. John F. Paulson Search for more papers by this author. Susan Solomon Search for more papers by this author. This is my first response to an article here and certainly hope that the science taskers here will listen carefully to any process or information I share as it will be different than what you have been trained to be true.

The earths grid system provides the gases for our eco-system and carbon is the result of a carbohydrate. All of the GHG warming folks have to find a vehicle to support that theory,and it is just their theory. Grid energy enhancement from processes in the universe have provided the weather anomalies and heating of the magma from grid energy being fed into it.

Science folks who are not curious enough to seek out grid science are not scientists,they just dont meet the standard definition. As a scientist,you have the responsibility to not make assumptions about someones science theory without a proper inspection of all of the evidence. I suspect that all of the old science teachers are well retired or gone as that used to be trained into every science tasker. Grid scientists such as myself are tougher environmentalists than most of the GHG folks,we really are.

But when the earths processes are more understood,folks may be champions for the problems we need to face first. But the facts are that Jets are responsible for more atmospheric carbon than any other mechanism. Would the industry stop those jets as we have called for and built a complete train system as designed by us?? Here is a statement that I make from time to time that speaks to earths processes and gives a tickle to so many science folks,but is totally true.

You can remove every plant on this planet and still breathe for centuries,you just cannot eat. How many science folks are in favor of their economy being destroyed with their own hands on the haft of the knife?? Much of the CO2 gets reabsorbed into the oceans when the global temperature drops. But when there is global warming, and the oceans release CO2 and extra H2O, the best thing to do is grow crops, and put extra wheat, rye, oats, rice, etc. Russ, In my paradigm, plants that create a carbohydrate in the root system flow the liquid sugar to the plant for its growth processes as fuel.

When that fuel is exhausted,a tone opens the stomata or gas pressure opens the stomata by force and exhausts the carbon waste. The plant always has oxygen around it as the aether is connected to the oxygens and seeks ground,therefore plants like trees with roots into the earth become a conductor. So you see,this grid scientist does not agree with the photosynthesis theory as he knows all oxygenation for the planet comes from the gas planet that has the proper speed and tone to provide the oxygens frequency and the sun which also has oxygen lines flowing to it for its frequency burn does not require the geneticists to build a plant that produces any oxygen as it is physically impossible.

Lifetimes of Fluorinated Compounds Lifetimes of Fluorinated Compounds
Lifetimes of Fluorinated Compounds Lifetimes of Fluorinated Compounds
Lifetimes of Fluorinated Compounds Lifetimes of Fluorinated Compounds
Lifetimes of Fluorinated Compounds Lifetimes of Fluorinated Compounds
Lifetimes of Fluorinated Compounds Lifetimes of Fluorinated Compounds
Lifetimes of Fluorinated Compounds Lifetimes of Fluorinated Compounds

Related Lifetimes of Fluorinated Compounds



Copyright 2019 - All Right Reserved