Under simulated atmospheric condition, photoomdation for HCFC-22 + H2O2, HCFC-22 + H2O2+O2, HFC-134A + H2O2 and HFC-134A + H2O2+ O2 systems were studied.H2O2 was irradiated by low pressure mercury lamp and produced OH...Under simulated atmospheric condition, photoomdation for HCFC-22 + H2O2, HCFC-22 + H2O2+O2, HFC-134A + H2O2 and HFC-134A + H2O2+ O2 systems were studied.H2O2 was irradiated by low pressure mercury lamp and produced OH radicals. The OH radicals can initiate photooxidation of HCFC-22 and 134A. The products of photooxidation were determined by a Fourier Transform infrared Spectroscopy with a 20ml long path cell. The products were COF2,CO2, HCI, H2O and HF for HCFC-22 + H2O2 system, HO, CO2, HCI and HF for HCFC-22 +H2O2 +O2 system, HCOF, CF3OOCF3,CO2, H2O and HF for HFC-134A +H2O2 system, HCOF, CO2, H2O, and HF for HFC-134A + H2O2+ O2 system. Based on those results, the mechanisms of photooxidation were suggested.展开更多
An accurate and reasonable technique combining direct absorption spectroscopy and laser-induced fluorescence（LIF）methods is developed to quantitatively measure the concentrations of hydroxyl in CH;/air flat laminar ...An accurate and reasonable technique combining direct absorption spectroscopy and laser-induced fluorescence（LIF）methods is developed to quantitatively measure the concentrations of hydroxyl in CH;/air flat laminar flame. In our approach, particular attention is paid to the linear laser-induced fluorescence and absorption processes, and experimental details as well. Through measuring the temperature, LIF signal distribution and integrated absorption, spatially absolute OH concentrations profiles are successfully resolved. These experimental results are then compared with the numerical simulation. It is proved that the good quality of the results implies that this method is suitable for calibrating the OH-PLIF measurement in a practical combustor.展开更多
UV-pulsed laser cavity ringdown spectroscopy of the hydroxyl radical OH(A–X)(0–0)band in the wavelength range of 306–310 nm was employed to determine absolute number densities of OH in the atmospheric helium plasma...UV-pulsed laser cavity ringdown spectroscopy of the hydroxyl radical OH(A–X)(0–0)band in the wavelength range of 306–310 nm was employed to determine absolute number densities of OH in the atmospheric helium plasma jets generated by a 2.45 GHz microwave plasma source.The effect of the addition of molecular gases N2 and O2 to He plasma jets on OH generation was studied.Optical emission spectroscopy was simultaneously employed to monitor reactive plasma species.Stark broadening of the hydrogen Balmer emission line(Hβ)was used to estimate the electron density ne in the jets.For both He/N2 and He/O2 jets,ne was estimated to be on the order of 10^15 cm^?3.The effects of plasma power and gas flow rate were also studied.With increase in N2 and O2 flow rates,ne tended to decrease.Gas temperature in the He/O2 plasma jets was elevated compared to the temperatures in the pure He and He/N2 plasma jets.The highest OH densities in the He/N2 and He/O2 plasma jets were determined to be 1.0×10^16 molecules/cm^3 at x=4 mm(from the jet orifice)and 1.8×10^16 molecules/cm^3 at x=3 mm,respectively.Electron impact dissociation of water and water ion dissociative recombination were the dominant reaction pathways,respectively,for OH formation within the jet column and in the downstream and far downstream regions.The presence of strong emissions of the N2^+ bands in both He/N2 and He/O2 plasma jets,as against the absence of the N2^+ emissions in the Ar plasma jets,suggests that the Penning ionization process is a key reaction channel leading to the formation of N2^+ in these He plasma jets.展开更多
In this paper the OH radicals produced by a needle-plate negative DC discharge in water vapor,N_(2)+H_(2)O mixture gas and He+H_(2)O mixture gas are investigated by a laser-induced fluorescence(LIF)system.With a balla...In this paper the OH radicals produced by a needle-plate negative DC discharge in water vapor,N_(2)+H_(2)O mixture gas and He+H_(2)O mixture gas are investigated by a laser-induced fluorescence(LIF)system.With a ballast resistor in the circuit,the discharge current is limited and the discharges remain in glow.The OH rotation temperature is obtained from fluorescence rotational branch fitting,and is about 350 K in pure water vapor.The effects of the discharge current and gas pressure on the production and quenching processes of OH radicals are investigated.The results show that in water vapor and He+H_(2)O mixture gas the fluorescence intensity of OH stays nearly constant with increasing discharge current,and in N_(2)+H_(2)O mixture gas the fluorescence intensity of OH increases with increasing discharge current.In water vapor and N_(2)+H_(2)O mixture gas the fluorescence intensity of OH decreases with increasing gas pressure in the studied pressure range,and in He+H_(2)O mixture gas the fluorescence intensity of OH shows a maximum value within the studied gas pressure range.The physicochemical reactions between electrons,radicals,ground and metastable molecules are discussed.The results in this work contribute to the optimization of plasma reactivity and the establishment of a molecule reaction dynamics model.展开更多
Activated carbon （AC） supported silver catalysts were prepared by incipient wetness impregnation method and their catalytic performance for CO preferential oxidation （PROX） in excess H2 was evaluated. Ag/AC cataly...Activated carbon （AC） supported silver catalysts were prepared by incipient wetness impregnation method and their catalytic performance for CO preferential oxidation （PROX） in excess H2 was evaluated. Ag/AC catalysts, after reduction in H2 at low temperatures （≤200 ℃） following heat treatment in He at 200 ℃ （He200H200）, exhibited the best catalytic properties. Temperature-programmed desorption （TPD）, X-ray diffraction （XRD） and temperature-programmed reduction （TPR） results indicated that silver oxides were produced during heat treatment in He at 200 ℃ which were reduced to metal silver nanoparticles in H2 at low temperatures （≤200 ℃）, simultaneously generating the adsorbed water/OH. CO conversion was enhanced 40% after water treatment following heat treatment in He at 600 ℃. These results imply that the metal silver nanoparticles are the active species and the adsorbed water/OH has noticeable promotion effects on CO oxidation. However, the promotion effect is still limited compared to gold catalysts under the similar conditions, which may be the reason of low selectivity to CO oxidation in PROX over silver catalysts. The reported Ag/AC-S-He catalyst after He200H200 treatment displayed similar PROX of CO reaction properties to Ag/SiO2. This means that Ag/AC catalyst is also an efficient low-temperature CO oxidation catalyst.展开更多
In recent years,significant increases in waste processing and material engineering have been seen by using advanced oxidation processes.The treatment results and energy yields of these processes are largely determined...In recent years,significant increases in waste processing and material engineering have been seen by using advanced oxidation processes.The treatment results and energy yields of these processes are largely determined by the generation and retention of reactive oxygen species(ROS).However,increasing the amount of ROS remains a key challenge because of the unavailability of performance-and energy-efficient techniques.In this study,plasma electrolysis,ultrasound,and plasma electrolysis combined with ultrasound were used to treat dimethyl sulfoxide(DMSO)solutions,and the results showed that the two methods can synergistically convert filament discharge into spark discharge,and the conversion of the discharge mode can significantly increase the concentration of OH radicals and effectively improve the efficiency of DMSO degradation.We verified the rationality of the results by analyzing the mass transfer path of ROS based on the reaction coefficients and found that the OH radicals in aqueous solution were mainly derived from the decomposition of hydrogen peroxide.These findings indicated that the synergistic action of plasma electrolysis and ultrasound can enhance the production of chemically reactive species,and provide new insights and guiding principles for the future translation of this combined strategy into real-life applications.Our results demonstrated that the synergistic strategy of ultrasound and plasma electrolysis is feasible in the switching mode and increasing the ROS,and may open new routes for materials engineering and pollutant degradation.展开更多
Photodissociation of p-aminobenzoic acid at 266 nm was investigated by probing the nascent OH photoproduct employing the laser-induced fluorescence technique. It was found that the nascent OH radical was vibrationally...Photodissociation of p-aminobenzoic acid at 266 nm was investigated by probing the nascent OH photoproduct employing the laser-induced fluorescence technique. It was found that the nascent OH radical was vibrationally cold and its rotational state distribution conformed to be a Boltzmann behavior, characterized by a rotational temperature of 1040±110 K. The rotational energy of OH was determined to be 8.78±0.84 kJ/mol. Between the two spinorbit states of OH, ^2Ⅱ3/2 and ^2Ⅱ1/2, the former was found to be preferentially populated. The distribution of the II（A＇） state for the A-doublet was dominant. Finally, a probable mechanism for the formation of OH produced from the photodissociation of p-aminobenzoic acid is discussed.展开更多
Plasma produced many active species such as OH radical and H radical. As well known, OH radical plays an important role in degrading complex pollutants. This study aims to measure the production of OH radicals and eva...Plasma produced many active species such as OH radical and H radical. As well known, OH radical plays an important role in degrading complex pollutants. This study aims to measure the production of OH radicals and evaluate important parameters that have influent in degradation process of waste water contains ammonia in circulated system and analyze the level of energy consumptions are resulted by this research. The production of OH radical was detected by formation of hydrogen peroxide which was resulted by recombination reaction between OH radicals during plasma electrolysis process. From the measured concentration of hydrogen peroxide, obtained concentration of OH radical is 2,020 ppm. The depth of anode, applied voltage and ammonia initial concentration have affected ammonia degradation percentage and energy consumption level. The highest result for ammonia degradation percentage is 63.2% which gets from applied voltage 700 V, with depth of anode 1 cm, initial concentration of ammonia 100 ppm, and lowest energy consumption of 110 KJ/mmol.展开更多
Photolysis rate （J1） and reaction rate constants （kl） for the biacetyl （butane-2,3-dione） were evaluated in aqueous phase using a continuous photolysis system with a conventional Xe-Hg arc lamp as a light source...Photolysis rate （J1） and reaction rate constants （kl） for the biacetyl （butane-2,3-dione） were evaluated in aqueous phase using a continuous photolysis system with a conventional Xe-Hg arc lamp as a light source. The OH radicals was generated by H2OE/UV process and biacetyl （CH3C（O）C（O）CH3） concentrations were monitored using 2,4-DNPH derivatization method. 2,3-butanedione molecule is widely present in the atmosphere, it have been detected in hydrometeors （fogs, rain, and clouds） and at a significant yield （up to 10μmolar）. The measurements were performed at 294 K and with free pH values. Our results lead to the following obtained values： J1= 3×10^-4 S^-1 and k1 = （6.17±0.95）×10^8 M^-1·s^-1.The uncertainty listed above is ±15%.展开更多
A new method was introduced to detect the concentration of OH radical in dielectric barrier discharge(DBD)reaction.A film, which was impregnated with salicylic acid,was used to detect OH radical in plasma reaction at ...A new method was introduced to detect the concentration of OH radical in dielectric barrier discharge(DBD)reaction.A film, which was impregnated with salicylic acid,was used to detect OH radical in plasma reaction at room temperature and atmospheric pressure.Salicylic acid reacts with OH radical and produces 2,5-dihydroxybenzoic acid(2,5-DHBA).Then,a high performance liquid chromatography(HPLC)was carried out to detect the concentration of 2,5-DHBA.Therefore,OH radical in nonthermal plasma reaction could be...展开更多
Using fogdrops of OH^· radicals to eliminate microbial contamination is an effective way to solve the current domestic and international problem. The results show that the threshold of OH solution used in the exp...Using fogdrops of OH^· radicals to eliminate microbial contamination is an effective way to solve the current domestic and international problem. The results show that the threshold of OH solution used in the experiment is 0.6 mg/L, the lethal time is 1 s, and the spray density of OH solution is 21 μL/m^2. The experimental results show that the OH radical possesses the following advantages： celerity, low lethal concentration and spray density, short lethal time, and absence of secondary pollution.展开更多
In this paper, a pulsed-dc CH;OH/Ar plasma jet generated at atmospheric pressure is studied by laser-induced fluorescence（LIF） and optical emission spectroscopy（OES）. A gas–liquid bubbler system is proposed to in...In this paper, a pulsed-dc CH;OH/Ar plasma jet generated at atmospheric pressure is studied by laser-induced fluorescence（LIF） and optical emission spectroscopy（OES）. A gas–liquid bubbler system is proposed to introduce the methanol vapor into the argon gas, and the CH3OH/Ar volume ratio is kept constant at about 0.1%. Discharge occurs in a 6-mm needle-to-ring gap in an atmospheric-pressure CH;OH/Ar mixture. The space-resolved distributions of OH LIF inside and outside the nozzle exhibit distinctly different behaviors. And, different production mechanisms of OH radicals in the needle-to-ring discharge gap and afterglow of plasma jet are discussed. Besides, the optical emission lines of carbonaceous species, such as CH, CN, and C;radicals, are identified in the CH;OH/Ar plasma jet. Finally, the influences of operating parameters（applied voltage magnitude, pulse frequency, pulsewidth） on the OH radical density are also presented and analyzed.展开更多
OH radicals and O atoms are two of the most important reactive species of non-equilibrium atmospheric pressure plasma(NAPP),which plays an important role in applications such as plasma medicine.However,experimental st...OH radicals and O atoms are two of the most important reactive species of non-equilibrium atmospheric pressure plasma(NAPP),which plays an important role in applications such as plasma medicine.However,experimental studies on how the gas content affects the postdischarge temporal evolutions of OH and O in the noble gas ns-NAPP are very limited.In this work,the effect of the percentages of O_(2),N_(2),and H_(2)O on the amounts of OH and O productions and their post-discharge temporal behaviors in ns-NAPP is investigated by laser-induced fluorescence(LIF)method.The results show that the productions of OH and O increase and then decrease with the increase of O_(2)percentage.Both OH and O densities reach their maximum when about 0.8%O_(2)is added.Further increase of the O_(2)concentration results in a decrease of the initial densities of both OH and O,and leads to their faster decay.The increase of N_(2)percentage also results in the increase and then decrease of the OH and O densities,but the change is smaller.Furthermore,when the H_(2)O concentration is increased from 100 to 3000 ppm,the initial OH density increases slightly,but the OH density decays much faster,while the initial density of O decreases with the increase of the H_(2)O concentration.After analysis,it is found that OH and O are mainly produced through electron collisional dissociation.O(^(1)D)is critical for OH generation.O_(3)accelerates the consumption processes of OH and O at high O_(2)percentage.The addition of H_(2)O in the NAPP considerably enhances the electronegativity,while it decreases the overall plasma reactivity,accelerates the decay of OH,and reduces the O atom density.展开更多
采用CCSD(T)//B3LYP/6-311+G(d,p)方法研究了Criegee中间体CH_3CHOO与OH自由基反应的微观机理.结果表明,上述反应存在抽氢、加成-分解和氧化3类反应通道,其中,syn-CH3CHOO+OH以抽β-H为优势通道,表观活化能为-4.88 k J/mol;anti-CH_3CHO...采用CCSD(T)//B3LYP/6-311+G(d,p)方法研究了Criegee中间体CH_3CHOO与OH自由基反应的微观机理.结果表明,上述反应存在抽氢、加成-分解和氧化3类反应通道,其中,syn-CH3CHOO+OH以抽β-H为优势通道,表观活化能为-4.88 k J/mol;anti-CH_3CHOO+OH则以加成-分解反应为优势通道,表观活化能为-13.25 k J/mol.在加成-分解和氧化反应通道中,anti-构象的能垒均低于syn-构象,而抽氢反应则是syn-(β-H)的能垒低于anti-构象.速率常数计算表明,anti-构象的加成-分解反应通道具有显著的负温度效应;syn-和anti-构象的氧化通道具有显著的正温度效应.3类反应具有显著不同的温度效应,说明通过改变温度可显著调节3类反应的相对速率.展开更多
文摘Under simulated atmospheric condition, photoomdation for HCFC-22 + H2O2, HCFC-22 + H2O2+O2, HFC-134A + H2O2 and HFC-134A + H2O2+ O2 systems were studied.H2O2 was irradiated by low pressure mercury lamp and produced OH radicals. The OH radicals can initiate photooxidation of HCFC-22 and 134A. The products of photooxidation were determined by a Fourier Transform infrared Spectroscopy with a 20ml long path cell. The products were COF2,CO2, HCI, H2O and HF for HCFC-22 + H2O2 system, HO, CO2, HCI and HF for HCFC-22 +H2O2 +O2 system, HCOF, CF3OOCF3,CO2, H2O and HF for HFC-134A +H2O2 system, HCOF, CO2, H2O, and HF for HFC-134A + H2O2+ O2 system. Based on those results, the mechanisms of photooxidation were suggested.
基金supported by the National Natural Science Foundation of China(Grant No.11272338)the Science and Technology on Scramjet Key Laboratory Funding,China(Grant No.STSKFKT 2013004)the China Scholarship Council
文摘An accurate and reasonable technique combining direct absorption spectroscopy and laser-induced fluorescence（LIF）methods is developed to quantitatively measure the concentrations of hydroxyl in CH;/air flat laminar flame. In our approach, particular attention is paid to the linear laser-induced fluorescence and absorption processes, and experimental details as well. Through measuring the temperature, LIF signal distribution and integrated absorption, spatially absolute OH concentrations profiles are successfully resolved. These experimental results are then compared with the numerical simulation. It is proved that the good quality of the results implies that this method is suitable for calibrating the OH-PLIF measurement in a practical combustor.
基金supported by the National Science Foundation through the grant CBET-1066486
文摘UV-pulsed laser cavity ringdown spectroscopy of the hydroxyl radical OH(A–X)(0–0)band in the wavelength range of 306–310 nm was employed to determine absolute number densities of OH in the atmospheric helium plasma jets generated by a 2.45 GHz microwave plasma source.The effect of the addition of molecular gases N2 and O2 to He plasma jets on OH generation was studied.Optical emission spectroscopy was simultaneously employed to monitor reactive plasma species.Stark broadening of the hydrogen Balmer emission line(Hβ)was used to estimate the electron density ne in the jets.For both He/N2 and He/O2 jets,ne was estimated to be on the order of 10^15 cm^?3.The effects of plasma power and gas flow rate were also studied.With increase in N2 and O2 flow rates,ne tended to decrease.Gas temperature in the He/O2 plasma jets was elevated compared to the temperatures in the pure He and He/N2 plasma jets.The highest OH densities in the He/N2 and He/O2 plasma jets were determined to be 1.0×10^16 molecules/cm^3 at x=4 mm(from the jet orifice)and 1.8×10^16 molecules/cm^3 at x=3 mm,respectively.Electron impact dissociation of water and water ion dissociative recombination were the dominant reaction pathways,respectively,for OH formation within the jet column and in the downstream and far downstream regions.The presence of strong emissions of the N2^+ bands in both He/N2 and He/O2 plasma jets,as against the absence of the N2^+ emissions in the Ar plasma jets,suggests that the Penning ionization process is a key reaction channel leading to the formation of N2^+ in these He plasma jets.
基金supported by National Natural Science Foundation of China(No.51777091)Innovative Talents Team Project of‘Six Talent Peaks’of Jiangsu Province(No.TDJNHB-006)Postgraduate Research&Practice Innovation Program of Jiangsu Province in China(No.SJCX20_0345)。
文摘In this paper the OH radicals produced by a needle-plate negative DC discharge in water vapor,N_(2)+H_(2)O mixture gas and He+H_(2)O mixture gas are investigated by a laser-induced fluorescence(LIF)system.With a ballast resistor in the circuit,the discharge current is limited and the discharges remain in glow.The OH rotation temperature is obtained from fluorescence rotational branch fitting,and is about 350 K in pure water vapor.The effects of the discharge current and gas pressure on the production and quenching processes of OH radicals are investigated.The results show that in water vapor and He+H_(2)O mixture gas the fluorescence intensity of OH stays nearly constant with increasing discharge current,and in N_(2)+H_(2)O mixture gas the fluorescence intensity of OH increases with increasing discharge current.In water vapor and N_(2)+H_(2)O mixture gas the fluorescence intensity of OH decreases with increasing gas pressure in the studied pressure range,and in He+H_(2)O mixture gas the fluorescence intensity of OH shows a maximum value within the studied gas pressure range.The physicochemical reactions between electrons,radicals,ground and metastable molecules are discussed.The results in this work contribute to the optimization of plasma reactivity and the establishment of a molecule reaction dynamics model.
基金supported by the National Natural Science Foundation of China (No. 21207039)the Natural Science Foundation of Guangdong Province, China (Grant No. S2011010000737)+2 种基金the Doctoral Fund of Ministry of Education of China (20110172120017)the Fundamental Research Funds for the Central Universities (Grant No. 2011zm 0048)the Key Laboratory of Renewable Energy and Gas Hydrate, Chinese Academy of Sciences (No. Y007K1)
文摘Activated carbon （AC） supported silver catalysts were prepared by incipient wetness impregnation method and their catalytic performance for CO preferential oxidation （PROX） in excess H2 was evaluated. Ag/AC catalysts, after reduction in H2 at low temperatures （≤200 ℃） following heat treatment in He at 200 ℃ （He200H200）, exhibited the best catalytic properties. Temperature-programmed desorption （TPD）, X-ray diffraction （XRD） and temperature-programmed reduction （TPR） results indicated that silver oxides were produced during heat treatment in He at 200 ℃ which were reduced to metal silver nanoparticles in H2 at low temperatures （≤200 ℃）, simultaneously generating the adsorbed water/OH. CO conversion was enhanced 40% after water treatment following heat treatment in He at 600 ℃. These results imply that the metal silver nanoparticles are the active species and the adsorbed water/OH has noticeable promotion effects on CO oxidation. However, the promotion effect is still limited compared to gold catalysts under the similar conditions, which may be the reason of low selectivity to CO oxidation in PROX over silver catalysts. The reported Ag/AC-S-He catalyst after He200H200 treatment displayed similar PROX of CO reaction properties to Ag/SiO2. This means that Ag/AC catalyst is also an efficient low-temperature CO oxidation catalyst.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51877184 and 11474305)the National Science and Technology Major Project of China(Grant No.2011ZX05032-003-003)。
文摘In recent years,significant increases in waste processing and material engineering have been seen by using advanced oxidation processes.The treatment results and energy yields of these processes are largely determined by the generation and retention of reactive oxygen species(ROS).However,increasing the amount of ROS remains a key challenge because of the unavailability of performance-and energy-efficient techniques.In this study,plasma electrolysis,ultrasound,and plasma electrolysis combined with ultrasound were used to treat dimethyl sulfoxide(DMSO)solutions,and the results showed that the two methods can synergistically convert filament discharge into spark discharge,and the conversion of the discharge mode can significantly increase the concentration of OH radicals and effectively improve the efficiency of DMSO degradation.We verified the rationality of the results by analyzing the mass transfer path of ROS based on the reaction coefficients and found that the OH radicals in aqueous solution were mainly derived from the decomposition of hydrogen peroxide.These findings indicated that the synergistic action of plasma electrolysis and ultrasound can enhance the production of chemically reactive species,and provide new insights and guiding principles for the future translation of this combined strategy into real-life applications.Our results demonstrated that the synergistic strategy of ultrasound and plasma electrolysis is feasible in the switching mode and increasing the ROS,and may open new routes for materials engineering and pollutant degradation.
基金V. ACKNOWLEDGMENTS This work was supported by tile National Natural Science Foundation of China （No.20721004 and No.20833008）. Can-hua Zhou sincerely wishes to express thanks to Dr. Ju-long Sun for assistance in the experiments.
文摘Photodissociation of p-aminobenzoic acid at 266 nm was investigated by probing the nascent OH photoproduct employing the laser-induced fluorescence technique. It was found that the nascent OH radical was vibrationally cold and its rotational state distribution conformed to be a Boltzmann behavior, characterized by a rotational temperature of 1040±110 K. The rotational energy of OH was determined to be 8.78±0.84 kJ/mol. Between the two spinorbit states of OH, ^2Ⅱ3/2 and ^2Ⅱ1/2, the former was found to be preferentially populated. The distribution of the II（A＇） state for the A-doublet was dominant. Finally, a probable mechanism for the formation of OH produced from the photodissociation of p-aminobenzoic acid is discussed.
文摘Plasma produced many active species such as OH radical and H radical. As well known, OH radical plays an important role in degrading complex pollutants. This study aims to measure the production of OH radicals and evaluate important parameters that have influent in degradation process of waste water contains ammonia in circulated system and analyze the level of energy consumptions are resulted by this research. The production of OH radical was detected by formation of hydrogen peroxide which was resulted by recombination reaction between OH radicals during plasma electrolysis process. From the measured concentration of hydrogen peroxide, obtained concentration of OH radical is 2,020 ppm. The depth of anode, applied voltage and ammonia initial concentration have affected ammonia degradation percentage and energy consumption level. The highest result for ammonia degradation percentage is 63.2% which gets from applied voltage 700 V, with depth of anode 1 cm, initial concentration of ammonia 100 ppm, and lowest energy consumption of 110 KJ/mmol.
文摘Photolysis rate （J1） and reaction rate constants （kl） for the biacetyl （butane-2,3-dione） were evaluated in aqueous phase using a continuous photolysis system with a conventional Xe-Hg arc lamp as a light source. The OH radicals was generated by H2OE/UV process and biacetyl （CH3C（O）C（O）CH3） concentrations were monitored using 2,4-DNPH derivatization method. 2,3-butanedione molecule is widely present in the atmosphere, it have been detected in hydrometeors （fogs, rain, and clouds） and at a significant yield （up to 10μmolar）. The measurements were performed at 294 K and with free pH values. Our results lead to the following obtained values： J1= 3×10^-4 S^-1 and k1 = （6.17±0.95）×10^8 M^-1·s^-1.The uncertainty listed above is ±15%.
基金supported by the National Natural Sci-ence Foundation of China(No.50708021)the GuangzhouUniversity Xinmiao Project(No.gyf1-1001)the Guangzhou University Scientific Research Start-up Project(No.gyf1-1002)
文摘A new method was introduced to detect the concentration of OH radical in dielectric barrier discharge(DBD)reaction.A film, which was impregnated with salicylic acid,was used to detect OH radical in plasma reaction at room temperature and atmospheric pressure.Salicylic acid reacts with OH radical and produces 2,5-dihydroxybenzoic acid(2,5-DHBA).Then,a high performance liquid chromatography(HPLC)was carried out to detect the concentration of 2,5-DHBA.Therefore,OH radical in nonthermal plasma reaction could be...
基金National Natural Science Foundation of China(Nos.50578020,60471036)
文摘Using fogdrops of OH^· radicals to eliminate microbial contamination is an effective way to solve the current domestic and international problem. The results show that the threshold of OH solution used in the experiment is 0.6 mg/L, the lethal time is 1 s, and the spray density of OH solution is 21 μL/m^2. The experimental results show that the OH radical possesses the following advantages： celerity, low lethal concentration and spray density, short lethal time, and absence of secondary pollution.
基金supported by the National Natural Science Foundation of China(Grant Nos.11465013 and 11375041)the Natural Science Foundation of Jiangxi Province,China(Grant Nos.20151BAB212012 and 20161BAB201013)the International Science and Technology Cooperation Program of China(Grant No.2015DFA61800)
文摘In this paper, a pulsed-dc CH;OH/Ar plasma jet generated at atmospheric pressure is studied by laser-induced fluorescence（LIF） and optical emission spectroscopy（OES）. A gas–liquid bubbler system is proposed to introduce the methanol vapor into the argon gas, and the CH3OH/Ar volume ratio is kept constant at about 0.1%. Discharge occurs in a 6-mm needle-to-ring gap in an atmospheric-pressure CH;OH/Ar mixture. The space-resolved distributions of OH LIF inside and outside the nozzle exhibit distinctly different behaviors. And, different production mechanisms of OH radicals in the needle-to-ring discharge gap and afterglow of plasma jet are discussed. Besides, the optical emission lines of carbonaceous species, such as CH, CN, and C;radicals, are identified in the CH;OH/Ar plasma jet. Finally, the influences of operating parameters（applied voltage magnitude, pulse frequency, pulsewidth） on the OH radical density are also presented and analyzed.
基金supported by National Natural Science Foundation of China(Nos.52130701 and 51977096)the National Key Research and Development Program of China(No.2021YFE0114700)。
文摘OH radicals and O atoms are two of the most important reactive species of non-equilibrium atmospheric pressure plasma(NAPP),which plays an important role in applications such as plasma medicine.However,experimental studies on how the gas content affects the postdischarge temporal evolutions of OH and O in the noble gas ns-NAPP are very limited.In this work,the effect of the percentages of O_(2),N_(2),and H_(2)O on the amounts of OH and O productions and their post-discharge temporal behaviors in ns-NAPP is investigated by laser-induced fluorescence(LIF)method.The results show that the productions of OH and O increase and then decrease with the increase of O_(2)percentage.Both OH and O densities reach their maximum when about 0.8%O_(2)is added.Further increase of the O_(2)concentration results in a decrease of the initial densities of both OH and O,and leads to their faster decay.The increase of N_(2)percentage also results in the increase and then decrease of the OH and O densities,but the change is smaller.Furthermore,when the H_(2)O concentration is increased from 100 to 3000 ppm,the initial OH density increases slightly,but the OH density decays much faster,while the initial density of O decreases with the increase of the H_(2)O concentration.After analysis,it is found that OH and O are mainly produced through electron collisional dissociation.O(^(1)D)is critical for OH generation.O_(3)accelerates the consumption processes of OH and O at high O_(2)percentage.The addition of H_(2)O in the NAPP considerably enhances the electronegativity,while it decreases the overall plasma reactivity,accelerates the decay of OH,and reduces the O atom density.
文摘采用CCSD(T)//B3LYP/6-311+G(d,p)方法研究了Criegee中间体CH_3CHOO与OH自由基反应的微观机理.结果表明,上述反应存在抽氢、加成-分解和氧化3类反应通道,其中,syn-CH3CHOO+OH以抽β-H为优势通道,表观活化能为-4.88 k J/mol;anti-CH_3CHOO+OH则以加成-分解反应为优势通道,表观活化能为-13.25 k J/mol.在加成-分解和氧化反应通道中,anti-构象的能垒均低于syn-构象,而抽氢反应则是syn-(β-H)的能垒低于anti-构象.速率常数计算表明,anti-构象的加成-分解反应通道具有显著的负温度效应;syn-和anti-构象的氧化通道具有显著的正温度效应.3类反应具有显著不同的温度效应,说明通过改变温度可显著调节3类反应的相对速率.
