The Henry’s law constant of volatiles in polymer systems is a crucial parameter reflecting the gas-liquid equilibrium,which is very important for devolatilization.In this research,polyolefin elastomer(POE)-cyclohexan...The Henry’s law constant of volatiles in polymer systems is a crucial parameter reflecting the gas-liquid equilibrium,which is very important for devolatilization.In this research,polyolefin elastomer(POE)-cyclohexane and polydimethylsiloxane(PDMS)-hexane systems were studied,and the Henry’s law constant was obtained by measuring the gas phase equilibrium partial pressure when polymer solutions containing different mass fractions of volatiles reached a saturated state.The effects of temperature,type of volatiles,and polymer viscosity on the gas phase equilibrium partial pressure and Henry’s law constant of the volatiles were investigated.The results indicate that,with the increase of temperature and polymer viscosity,the gas phase equilibrium partial pressure and Henry’s law constant of volatiles increase.As temperature increases,the solubility of gas in liquid decreases.The relationship between the Henry’s law constant and temperature is consistent with the Arrhenius law.In the PDMS-hexane system,the gas phase equilibrium partial pressure and Henry’s law constant of n-hexane are higher than those of cyclohexane.The obtained Henry’s law constants can be used as a reference for perfecting the devolatilization process and improving the devolatilization effect.展开更多
Hydrogen peroxide is not only an important oxidant in itself; it also serves as both sink and temporary reservoir for other important oxidants including HOx （OH and HO2） radicals and O3 in the atmosphere. Its partit...Hydrogen peroxide is not only an important oxidant in itself; it also serves as both sink and temporary reservoir for other important oxidants including HOx （OH and HO2） radicals and O3 in the atmosphere. Its partitioning between gas and aqueous phases in the atmosphere, usually described by its Henry＇s law constant （KH）, significantly influences its role in atmospheric processes. Large discrepancies between the KH values reported in previous work, however, have created uncertainty for atmospheric modelers. Based on our newly developed online instrumentation, we have re-determined the temperature and acidity dependence of KH for hydrogen peroxide at an air pressure of （0.960 ± 0.013） atm （1 atm = 1.01325 × 10^5 Pa）. The results indicated that the temperature dependence of KH for hydrogen peroxide fits to the Van＇t Hoff equation form, expressed as lnKH = a/T - b, and a = -△H/R, where KH is in M/atm （M is mol/L）, T is in degrees Kelvin, R is the ideal gas constant, and AH is the standard heat of solution. For acidity dependence, results demonstrated that the KH value of hydrogen peroxide appeared to have no obvious dependence on decreasing pH level （from pH 7 to pH 1）. Combining the dependence of both temperature and acidity, the obtained a and b were 7024 ± 138 and 11.97 ± 0.48, respectively, AH was （58.40 ± 1.15） kJ/（K.mol）, and the uncertainties represent σ. Our determined KH values for hydrogen peroxide will therefore be of great use in atmospheric models.展开更多
The Henry＇s Law constant （k） for phosphine in seawater was determined by multiple phase equilibration combined with headspace gas chromatography. The effects of pH, temperature, and salinity on k were studied. The ...The Henry＇s Law constant （k） for phosphine in seawater was determined by multiple phase equilibration combined with headspace gas chromatography. The effects of pH, temperature, and salinity on k were studied. The k value for phosphine in natural seawater was 6.415 at room temperature （approximately 23℃）. This value increases with increases in temperature and salinity, but no obvious change was observed at different pH levels. At the same temperature, there was no significant difference between the k for phosphine in natural seawater and that in artificial seawater. This implies that temperature and salinity are major determining factors for k in marine environment. Double linear regression with Henry＇s Law constants for phosphine as a function of temperature and salinity confirmed our observations. These results provide a basis for the measurement of trace phosphine concentrations in seawater, and will be helpful for future research on the status of phosphine in the oceanic biogeochemical cycle of phosphorus.展开更多
Vapor-liquid phase equilibrium data of tertpentanol in carbon dioxide were measured at temperatures of 313.4, 323.4, 333.5 and 343.5 K and in the pressure range of 4.56--11.44 MPa. The phase equilibium apparatus used ...Vapor-liquid phase equilibrium data of tertpentanol in carbon dioxide were measured at temperatures of 313.4, 323.4, 333.5 and 343.5 K and in the pressure range of 4.56--11.44 MPa. The phase equilibium apparatus used in the work was a variable-volume high-pressure cell. The experimental data were reasonably correlated with Peng-Robinson equation of state（PR-EOS） together with van der Waals-2 two-parameter mixing rules. Henry＇s Law constants and partial molar volumes of CO2 at infinite dilution were estimated with Krichevsky-Kasarnovsky equa- tion, and Henry＇s Law constants increase with increasing temperature, however, partial molar volumes of CO2 at infinite dilution are negative whose magnitudes decrease with temperature. Partial molar volumes of CO2 and tertpentanol in liquid phase at equilibrium were calculated.展开更多
报告了自行研制的质子转移反应质谱(Proton Transfer Reaction Mass Spectrometry,PTR-MS)装置结合动态气体提取技术直接测量水中苯浓度的新方法。N2连续地将水溶液中的苯提取出来,用质子转移反应质谱测量其在液面顶空中的分压强P随时...报告了自行研制的质子转移反应质谱(Proton Transfer Reaction Mass Spectrometry,PTR-MS)装置结合动态气体提取技术直接测量水中苯浓度的新方法。N2连续地将水溶液中的苯提取出来,用质子转移反应质谱测量其在液面顶空中的分压强P随时间的变化关系,从而得到苯的亨利常数H利用亨利定律就可以给出苯在水溶液中的浓度。考察了苯在提取气体及水溶液中达到平衡需要的液面高度,测量了28℃时苯的亨利常数。以此为基础测试了水中苯的浓度,测量结果与配制的溶液浓度相一致。PTR-MS结合动态气体提取技术测量水中苯的浓度,检出限为1μg/L。方法可以拓展到水中其它挥发性有机物浓度的测量。展开更多
Volatile organic compounds （VOCs） are widely used in various industrial processes and generate water pollutions. VOCs removal from raw water is an important task for waterworks to guarantee drinking water security. ...Volatile organic compounds （VOCs） are widely used in various industrial processes and generate water pollutions. VOCs removal from raw water is an important task for waterworks to guarantee drinking water security. The removal of VOCs such as chlorobenzene （CB） and ethylbenzene （EB） from raw water by air stripping was investigated under various conditions, inciuding the variation of temperature （5-30~C）, pH （3.5-10.5）, and air/water ratio （10-60）. The air stripping removal efficiency of VOCs decreased with VOCs concentration declining in water. And Henry＇s law constant was demonstrated as an indicator of the estimation of VOCs removal efficiency for air stripping. The effects of temperature and the ratio of air and water were found to play a great role in VOCs removal, but the effect of pH seemed to be negligible. This study demonstrates that air stripping provides a promising opportunity in removing VOCs in drinking water treatment, especially for the relatively high concentration of VOCs.展开更多
基金Polyolefin Elastomer Technology Development project(2020B-2619).
文摘The Henry’s law constant of volatiles in polymer systems is a crucial parameter reflecting the gas-liquid equilibrium,which is very important for devolatilization.In this research,polyolefin elastomer(POE)-cyclohexane and polydimethylsiloxane(PDMS)-hexane systems were studied,and the Henry’s law constant was obtained by measuring the gas phase equilibrium partial pressure when polymer solutions containing different mass fractions of volatiles reached a saturated state.The effects of temperature,type of volatiles,and polymer viscosity on the gas phase equilibrium partial pressure and Henry’s law constant of the volatiles were investigated.The results indicate that,with the increase of temperature and polymer viscosity,the gas phase equilibrium partial pressure and Henry’s law constant of volatiles increase.As temperature increases,the solubility of gas in liquid decreases.The relationship between the Henry’s law constant and temperature is consistent with the Arrhenius law.In the PDMS-hexane system,the gas phase equilibrium partial pressure and Henry’s law constant of n-hexane are higher than those of cyclohexane.The obtained Henry’s law constants can be used as a reference for perfecting the devolatilization process and improving the devolatilization effect.
基金supported by the National Natural Science Foundation of China (No.40875072,20677002)
文摘Hydrogen peroxide is not only an important oxidant in itself; it also serves as both sink and temporary reservoir for other important oxidants including HOx （OH and HO2） radicals and O3 in the atmosphere. Its partitioning between gas and aqueous phases in the atmosphere, usually described by its Henry＇s law constant （KH）, significantly influences its role in atmospheric processes. Large discrepancies between the KH values reported in previous work, however, have created uncertainty for atmospheric modelers. Based on our newly developed online instrumentation, we have re-determined the temperature and acidity dependence of KH for hydrogen peroxide at an air pressure of （0.960 ± 0.013） atm （1 atm = 1.01325 × 10^5 Pa）. The results indicated that the temperature dependence of KH for hydrogen peroxide fits to the Van＇t Hoff equation form, expressed as lnKH = a/T - b, and a = -△H/R, where KH is in M/atm （M is mol/L）, T is in degrees Kelvin, R is the ideal gas constant, and AH is the standard heat of solution. For acidity dependence, results demonstrated that the KH value of hydrogen peroxide appeared to have no obvious dependence on decreasing pH level （from pH 7 to pH 1）. Combining the dependence of both temperature and acidity, the obtained a and b were 7024 ± 138 and 11.97 ± 0.48, respectively, AH was （58.40 ± 1.15） kJ/（K.mol）, and the uncertainties represent σ. Our determined KH values for hydrogen peroxide will therefore be of great use in atmospheric models.
基金Supported by the National Natural Science Foundation of China (Nos.30970522,40576058)the National Natural Science Foundation of China for Creative Research Groups (No.41121064)
文摘The Henry＇s Law constant （k） for phosphine in seawater was determined by multiple phase equilibration combined with headspace gas chromatography. The effects of pH, temperature, and salinity on k were studied. The k value for phosphine in natural seawater was 6.415 at room temperature （approximately 23℃）. This value increases with increases in temperature and salinity, but no obvious change was observed at different pH levels. At the same temperature, there was no significant difference between the k for phosphine in natural seawater and that in artificial seawater. This implies that temperature and salinity are major determining factors for k in marine environment. Double linear regression with Henry＇s Law constants for phosphine as a function of temperature and salinity confirmed our observations. These results provide a basis for the measurement of trace phosphine concentrations in seawater, and will be helpful for future research on the status of phosphine in the oceanic biogeochemical cycle of phosphorus.
基金Supported by the Youth Key Teacher Foundation of Henan Educational Committee,China(No.2010GGJS-162)
文摘Vapor-liquid phase equilibrium data of tertpentanol in carbon dioxide were measured at temperatures of 313.4, 323.4, 333.5 and 343.5 K and in the pressure range of 4.56--11.44 MPa. The phase equilibium apparatus used in the work was a variable-volume high-pressure cell. The experimental data were reasonably correlated with Peng-Robinson equation of state（PR-EOS） together with van der Waals-2 two-parameter mixing rules. Henry＇s Law constants and partial molar volumes of CO2 at infinite dilution were estimated with Krichevsky-Kasarnovsky equa- tion, and Henry＇s Law constants increase with increasing temperature, however, partial molar volumes of CO2 at infinite dilution are negative whose magnitudes decrease with temperature. Partial molar volumes of CO2 and tertpentanol in liquid phase at equilibrium were calculated.
文摘报告了自行研制的质子转移反应质谱(Proton Transfer Reaction Mass Spectrometry,PTR-MS)装置结合动态气体提取技术直接测量水中苯浓度的新方法。N2连续地将水溶液中的苯提取出来,用质子转移反应质谱测量其在液面顶空中的分压强P随时间的变化关系,从而得到苯的亨利常数H利用亨利定律就可以给出苯在水溶液中的浓度。考察了苯在提取气体及水溶液中达到平衡需要的液面高度,测量了28℃时苯的亨利常数。以此为基础测试了水中苯的浓度,测量结果与配制的溶液浓度相一致。PTR-MS结合动态气体提取技术测量水中苯的浓度,检出限为1μg/L。方法可以拓展到水中其它挥发性有机物浓度的测量。
基金National High Technology Research and Development Program of China(863 program)(No.2008AA06A414)Major Science and Technology Proyran for Water Pollution Control and Treatment,China(No.2008ZX07421-003)
文摘Volatile organic compounds （VOCs） are widely used in various industrial processes and generate water pollutions. VOCs removal from raw water is an important task for waterworks to guarantee drinking water security. The removal of VOCs such as chlorobenzene （CB） and ethylbenzene （EB） from raw water by air stripping was investigated under various conditions, inciuding the variation of temperature （5-30~C）, pH （3.5-10.5）, and air/water ratio （10-60）. The air stripping removal efficiency of VOCs decreased with VOCs concentration declining in water. And Henry＇s law constant was demonstrated as an indicator of the estimation of VOCs removal efficiency for air stripping. The effects of temperature and the ratio of air and water were found to play a great role in VOCs removal, but the effect of pH seemed to be negligible. This study demonstrates that air stripping provides a promising opportunity in removing VOCs in drinking water treatment, especially for the relatively high concentration of VOCs.
