Ketoprofen(KET),as a non-steroidal anti-inflammatory drug frequently detected in aqueous environments,is a threat to human health due to its accumulation and low biodegradability,which requires the transformation and ...Ketoprofen(KET),as a non-steroidal anti-inflammatory drug frequently detected in aqueous environments,is a threat to human health due to its accumulation and low biodegradability,which requires the transformation and degradation of KET in aqueous environments.In this paper,the reaction process of ozone-initiated KET degradation in water was investigated using density functional theory(DFT)method at the M06-2X/6-311++g(3df,2p)//M06-2X/6-31+g(d,p)level.The detailed reaction path of KET ozonation is proposed.The thermodynamic results show that ozone-initiated KET degradation is feasible.Under ultraviolet irradiation,the reaction of ozone with water can also produce OH radicals(HO·)that can react with KET.The degradation reaction of KET caused by HO·was further studied.The kinetic calculation illustrates that the reaction rate(1.99×10-1(mol/L)^(-1)sec^(-1))of KET ozonation is relatively slow,but the reaction rate of HO·reaction is relatively high,which can further improve the degradation efficiency.On this basis,the effects of pollutant concentration,ozone concentration,natural organic matter,and pH value on degradation efficiency under UV/O3 process were analyzed.The ozonolysis reaction of KET is not sensitive to pH and is basically unaffected.Finally,the toxicity prediction of oxidation compounds produced by degradation reaction indicates that most of the degradation products are harmless,and a few products containing benzene rings are still toxic and have to be concerned.This study serves as a theoretical basis for analyzing the migration and transformation process of anti-inflammatory compounds in the water environment.展开更多
Oxidation of organic amines(OAs)or aromatic hydrocarbons(AHs)produces carbonyls,which further react with OAs to form carbonyl-amine condensation products,threatening environmental quality and human health.However,ther...Oxidation of organic amines(OAs)or aromatic hydrocarbons(AHs)produces carbonyls,which further react with OAs to form carbonyl-amine condensation products,threatening environmental quality and human health.However,there is still a lack of systematic understanding of the carbonyl-amine condensation reaction processes of OAs or between OAs and AHs,and subsequent environmental health impact.This work systematically investigated the carbonyl-amine condensation coupled ozonolysis kinetics,reaction mechanism,secondary organic aerosol(SOA)formation and cytotoxicity fromthe mixture of dipropylamine(DPA)and styrene(STY)by a combined method of productmass spectrometry identification,particle property analysis and cell exposure evaluation.The results from ozonolysis of DPA and STY mixture revealed that STY inhibited the ozonolysis of DPA to different degrees to accelerate its own decay rate.The barycenter of carbonyl-amine condensation reactionswas shifted from inside of DPA to between DPA and STY,which accelerated STY ozonolysis,but slowed down DPA ozonolysis.For the first time,ozonolysis of DPA and STY mixture to complex carbonyl-amine condensation products through the reactions of DPA with its carbonyl products,DPA with STY’s carbonyl products and DPA’s bond breakage product with STY’s carbonyl products was confirmed.These condensation products significantly contributed to the formation and growth of SOA.The SOA containing particulate carbonyl-amine condensation products showed definite cytotoxicity.These findings are helpful to deeply and comprehensively understand the transformation,fate and environmental health effects of mixed organics in atmospheric environment.展开更多
Elucidating the mutual effects between the different volatile organic compounds(VOCs)is crucial for comprehending the formation mechanism of atmospheric secondary organic aerosols(SOA).Here,the mixed VOCs experiments ...Elucidating the mutual effects between the different volatile organic compounds(VOCs)is crucial for comprehending the formation mechanism of atmospheric secondary organic aerosols(SOA).Here,the mixed VOCs experiments of isoprene and△^(3)-carene/β-caryophyllene were carried out in the presence of O_(3)using an indoor smog chamber.The suppression effect of isoprene was recognized by the scanning mobility particle sizer spectrometer,online vacuum ultraviolet free electron laser(VUV-FEL)photoionization aerosol mass spectrometry,and quantum chemical calculations.The results indicate that the suppression effect of isoprene on the ozonolysis of△^(3)-carene andβ-caryophyllene shows fluctuating and monotonous trends,respectively.The carbon content of the precursor could be themain factor for regulating the strength of the suppression effect.Plausible structures and formation mechanisms of several new products generated from the single VOC precursor and VOC-cross-reaction are proposed,which enrich the category of VOC oxidation products.Meanwhile,a new dimerization mechanism of the RO_(2)+R’O_(2)reaction is suggested,which offers an intriguing perspective on the gas phase formation process of particle phase accretion products.The present findings provide valuable insights into clarifying the pivotal roles played by isoprene in the interplay between different VOCs and understanding of SOA formation mechanisms of VOC mixtures,especially nearby the emission origins.展开更多
The ozonolysis of 2,3,7,8-tetra-chlorodibenzo-p-dioxin （2,3,7,8-TCDD） is an efficient degradation way in the atmosphere. The ozonolysis process and possible reactions path of Criegee Intermediates with NO and H2O ar...The ozonolysis of 2,3,7,8-tetra-chlorodibenzo-p-dioxin （2,3,7,8-TCDD） is an efficient degradation way in the atmosphere. The ozonolysis process and possible reactions path of Criegee Intermediates with NO and H2O are introduced in detail at the method of MPWB1K/6-31＋G（d,p）//MPWB1K/6- 311＋G（3df,2p） level. In ozonolysis, H2O is an important source of OH radical formation and initiated the subsequent degradation reaction. The Rice-Ramsperger-Kassel-Marcus （RRKM） theory was applied to calculate rate constants with the temperature ranging from 200 to 600 K. The rate constant of reaction between 2,3,7,8-TCDD and 03 is 4.80 × 10^-20 cm3/（mole.sec） at 298 K and 760 Tort. The atmospheric lifetime of the reaction species was estimated according to rate constants, which is helpful for the atmospheric model study on the degradation and risk assessment of dioxin.展开更多
An indoor chamber facility is described for investigation of atmospheric aerosol chemistry. Two sets of α-pinene ozonolysis experiments were conducted in the presence of dry ammonium sulfate seed particle: ozone limi...An indoor chamber facility is described for investigation of atmospheric aerosol chemistry. Two sets of α-pinene ozonolysis experiments were conducted in the presence of dry ammonium sulfate seed particle: ozone limited experiments and α-pinene limited experiments. The concentration of gas phase and particle phase species was monitored continuously by on-line instruments and recorded automatically by data sampling system. The evolution of size distribution was measured by a scanning mobility particle sizer ...展开更多
α-pinene is the most abundant monoterpene that represents an important family of volatile organic compounds.Molecular identification of key transient compounds during theα-pinene ozonolysis has been proven to be a c...α-pinene is the most abundant monoterpene that represents an important family of volatile organic compounds.Molecular identification of key transient compounds during theα-pinene ozonolysis has been proven to be a challenging experimental target because of a large number of intermediates and products involved.Here we exploit the recently developed hybrid instruments that integrate aerosol mass spectrometry with a vacuum ultraviolet free-electron laser to study theα-pinene ozonolysis.The experiments ofα-pinene ozonolysis are performed in an indoor smog chamber,with reactor having a volume of 2 m^(3) which is made of fluorinated ethylene propylene film.Distinct mass spectral peaks provide direct experimental signatures of previously unseen compounds produced from the reaction ofα-pinene with O_(3).With the aid of quantum chemical calculations,plausible mechanisms for the formation of these new compounds are proposed.These findings provide crucial information on fundamental understanding of the initial steps ofα-pinene oxidation and the subsequent processes of new particle formation.展开更多
The ozonolysis of cyclohexene is an important model system for understanding the more complex reaction of O_3 with monoterpenes; however, many previous studies have come to qualitatively different conclusions about th...The ozonolysis of cyclohexene is an important model system for understanding the more complex reaction of O_3 with monoterpenes; however, many previous studies have come to qualitatively different conclusions about the composition of the secondary organic aerosol(SOA)formed in this system. In the present study, the composition of the SOA produced by cyclohexene ozonolysis in the absence of seed aerosols has been investigated online and off-line using synchrotron-based thermal desorption/tunable vacuum ultraviolet photoionization time-of-flight aerosol mass spectrometry(TD-VUV-TOF-PIAMS) in conjunction with a custom-built smog chamber. On the basis of the molecular ions observed by mass spectrometry at 11.5 e V, it was found that dicarboxylic acids, dialdehydes, and cyclic anhydrides are the predominant low molecular weight components in the particle phase. The results also indicated that TD-VUV-TOF-PIAMS coupled with filter sampling is a potentially useful tool for the investigation of SOA composition both in the field and in the laboratory.展开更多
The α-pinene ozonolysis under the different environmental conditions were observed in a smog chamber. The second-order rate constant （k） was determined to be （7.25 ± 0.06） x 10^-17 cm^3/（molecule.sec） unde...The α-pinene ozonolysis under the different environmental conditions were observed in a smog chamber. The second-order rate constant （k） was determined to be （7.25 ± 0.06） x 10^-17 cm^3/（molecule.sec） under 20% of relative humidity （RH） and room temperature. RH showed a marked influence on the α-pinene ozonolysis. The value of k increased with KH increase, which was 1.6 times faster at RH = 80% than that at RH = 20%. Additionally, the value of k apparently changed in the presence of the aerosol particles. The diesel soot increased the k value. The fly ash prohibited the reaction, however, H2SO4-treated fly ash promoted the reaction. The information of products gained using FT-IR and SPAMS showed that pinonic acid, 10-hydroxy-pinonic acid and pinic acid could be generated during the α- pinene ozonolysis. Water molecules could take part in the formation of the products, and play a vital role in the degradation of α-pinene. The atmospheric residence time calculation showed that the ozonolysis in the atmosphere is an important way of the α-pinene consumption as compared to that reacted with OH during daytime. The results suggested that the degradation of α-pinene via the ozonization in the atmosphere may be affected greatly by RH, as well as the presence of aerosol particles. The ozonolysis reaction may be an important way of the a-pinene consumption during daytime.展开更多
Some unsaturated compounds with the required （Z,Z）-double bonds configuration are synthesized through controlled ozonolysis process of 1,5,9-cyclododecatriene by determining the necessary amount of ozone passing thr...Some unsaturated compounds with the required （Z,Z）-double bonds configuration are synthesized through controlled ozonolysis process of 1,5,9-cyclododecatriene by determining the necessary amount of ozone passing through to selectively guarantee the breakage of a double bond while leaving other two bonds as （Z,Z）. The products were diagnosed by using NMR spectrum, infrared （IR） and mass spectrometer techniques. It is concluded that these products could widely be used in the synthesis of insect pheromones instead of insecticides and as useful intermediate compounds in many chemical reactions.展开更多
Radical production in the ozonolysis of propene in air was monitored directly by a peroxy radical chemical amplification (PERCA) instrument at room temperature (298±2 K) and atmospheric pressure (1×105 Pa). ...Radical production in the ozonolysis of propene in air was monitored directly by a peroxy radical chemical amplification (PERCA) instrument at room temperature (298±2 K) and atmospheric pressure (1×105 Pa). The ozonolysis reactions were conducted in a flow tube under pseudo-first-order conditions for ozone. The decay in ozone was calculated based on reaction time tr and effective rate constant keff (keff = k1[C3H6]0)) for the ozone-propene reaction. The total radical yields relative to consumed ozone were determined to be 0.97±0.17 (σ). A box model was used to simulate radical production in the ozone-propene reaction. The model-derived radical yields agree well with those from experiment within the uncertainty of the two methods. In addition, the yields for OH, HO2 and CH3O2 were obtained from the measured total radical yields and radical partitioning derived from the box model. The yield is 0.39±0.08 (σ) for OH, 0.19±0.04 (σ) for HO2, and 0.39±0.08 (σ) for CH3O2. This work suggests that the previously measured radical yield by indirect method for the ozonolysis of propene may be underes-timated.展开更多
The production of radicals in the ozonolysis of ethene in air in a flow tube was monitored directly by a chemical amplification instrument at room temperature （298±2） K and 1 × 10^5 Pa. The radical yield i...The production of radicals in the ozonolysis of ethene in air in a flow tube was monitored directly by a chemical amplification instrument at room temperature （298±2） K and 1 × 10^5 Pa. The radical yield is 0.50± 0.08 （σ） and found to be independent of CO. The result shows that the indirectly measured radical yields for the ozonolysis of ethene may be underestimated by a factor of 2.展开更多
Cavity ring-down spectroscopy(CRDS)was utilized in combination with chemical titration with sulfur dioxide(SO_2)to quantify stabilized Criegee intermediates(s CIs)produced at low pressures(4–20 Torr)in ozonolysis rea...Cavity ring-down spectroscopy(CRDS)was utilized in combination with chemical titration with sulfur dioxide(SO_2)to quantify stabilized Criegee intermediates(s CIs)produced at low pressures(4–20 Torr)in ozonolysis reactions of cis-2-butene,2-methyl-2-butene,cyclopentene,and cyclohexene.The yield of stabilized s CI,acetaldehyde oxide(CH_3CHOO),from cis-2-butene ozonolysis decreased with decreasing pressure and reached to 0.05±0.04 at the zero-pressure limit.The nonsymmetric alkene 2-methyl-2-butene produced two stabilized s CIs,CH_3CHOO and acetone oxide((CH_3)_2COO),and their total yield decreased with decreasing pressure and reached 0.01±0.03 at the zero-pressure limit.For cyclopentene and cyclohexene,the s CI yields were essentially constant near zero,as expected of endocyclic alkenes.The nascent yields of s CI of various alkenes are compared.展开更多
Mineral aerosol particles significantly impact environmental risk prediction of liquid crystal monomers(LCMs).In this work,we investigated the reaction mechanisms and kinetics of three typical LCMs(4-cyano-3,5-difluor...Mineral aerosol particles significantly impact environmental risk prediction of liquid crystal monomers(LCMs).In this work,we investigated the reaction mechanisms and kinetics of three typical LCMs(4-cyano-3,5-difluorophenyl 4-ethylbenzoate(CEB-2F),4-cyano-3-fluorophenyl 4-ethylbenzoate(CEB-F),and 4-cyanophenyl 4-ethylbenzoate(CEB))with ozone(O_(3))in the atmospheric gas,liquid,and particle phases employing density functional theory(DFT).Here,O_(3)is prone to add to the benzene ring without F atom(s)in the selected LCMs.The ozonolysis products are aldehydes,carboxylic acids,epoxides,and unsaturated hydrocarbons containing aromatic rings.Those products undergo secondary ozonolysis to generate small molecular compounds such as glyoxal,which is beneficial for generating secondary organic aerosol(SOA).Titanium dioxide(TiO_(2)),an essential component of mineral aerosol particles,has good adsorption properties for LCMs;however,it slightly reduces the reactivity with O_(3).At 298 K,the reaction rate constant of the selected LCMs reacting with O_(3)in the gas and atmospheric liquid phases is(2.74–5.53)×10^(-24)cm^(3)/(mol·sec)and 5.58×10^(-3)–39.1 L/(mol·sec),while CEB-2F reacting with O_(3)on(TiO_(2))_(6)cluster is 1.84×10^(-24)cm^(3)/(mol·sec).The existence of TiO_(2)clusters increases the persistence and long-distance transportability of LCMs,which enlarges the contaminated area of LCMs.展开更多
A tunable diode laser absorption spectrometer （TDLAS） for formaldehyde atmospheric measurements has been set up and validated through comparison experiments with a Fourier transform infrared spectrometer （FT-IR） i...A tunable diode laser absorption spectrometer （TDLAS） for formaldehyde atmospheric measurements has been set up and validated through comparison experiments with a Fourier transform infrared spectrometer （FT-IR） in a simulation chamber.Formaldehyde was generated in situ in the chamber from reaction of ethene with ozone.Three HCHO ro-vibrational line intensities （at 2909.71,2912.09 and 2914.46 cm-1） possibly used by TDLAS were calibrated by FT-IR spectra simultaneously recorded in the 1600–3200 cm-1 domain during ethene ozonolysis,enabling the on-line deduction of the varying concentration for HCHO in formation.The experimental line intensities values inferred confirmed the calculated ones from the updated HITRAN database.In addition,the feasibility of stratospheric in situ HCHO measurements using the 2912.09 cm-1 line was demonstrated.The TDLAS performances were also assessed,leading to a 2σ detection limit of 88 ppt in volume mixing ratio with a response time of 60 sec at 30 Torr and 294 K for 112 m optical path.As part of this work,the room-temperature rate constant of this reaction and the HCHO formation yield were found to be in excellent agreement with the compiled literature data.展开更多
Synergetic effects for p-nitrophenol degradation were observed in the ozonation with ultrasonic enhancement. The enhancements of removal rate for p-nitrophenol and TOC were around 116% and 294% respectively in compari...Synergetic effects for p-nitrophenol degradation were observed in the ozonation with ultrasonic enhancement. The enhancements of removal rate for p-nitrophenol and TOC were around 116% and 294% respectively in comparison with the individual ultrasound and ozonation systems. The synergetic phenomenon is attributed to two physicochemical mechanisms: (1) Ultrasound decomposes ozone causing augmentation of the activity of free radicals; (2) Ultrasonic wave increased the concen- tration of O3 in solution because of ultrasonic dispersion.展开更多
This experimental study was carried out to verify the quality enhancement of Natural Rubber Products by drying methods and ascertain to what extent the different methods of drying affected the properties exhibited. Du...This experimental study was carried out to verify the quality enhancement of Natural Rubber Products by drying methods and ascertain to what extent the different methods of drying affected the properties exhibited. During this study, samples of natural rubber coagulum were obtained and a sample each was subjected to one of these three methods of drying: air, smoke and oven. The qualities of the dried rubber samples from the three methods of drying were then investigated. The criterion adopted for quality in this study was Plasticity Retention Index (PRI), which gave insight of the oxidative resistance of natural rubber, a measure of quality. The plasticity retention index was tested by using the Wallace plastimeter. The PRI values were calculated for the samples. Results obtained from this study showed that the qualities of natural rubber samples were actually influenced to different measurable extents depending on drying methods, as exhibited in the PRI levels. The results further gave basis for our conclusions that the smoke dried rubber samples had the poorest qualities, having the lowest values of PRI;followed by the oven and air dried samples respectively in terms of their PRI presented the best qualities, the highest PRI values.展开更多
Peroxy radicals （ROx） concentrations were measured by Peroxy Radical Chemical Amplifier （PERCA） technique during the field campaign RISFEX 2003 （RiShifi Fall Experiment 2003）, which was performed in September 20...Peroxy radicals （ROx） concentrations were measured by Peroxy Radical Chemical Amplifier （PERCA） technique during the field campaign RISFEX 2003 （RiShifi Fall Experiment 2003）, which was performed in September 2003 at Rishiri island （45.07 N, 141.12 E, and 35 m asl） in the sea of Japan. The concentrations of nighttime ROx radicals had temporal variations around an average of 7.9±5.8 （1σ） pptv and showed a positive correlation with the summed mixing ratio of four monoterpene species. Model calculations suggested that local nighttime ROx radicals were dominated by the reactions of monoterpene with ozone （03） and nitrate radical （NO3）, contributing ca. 76% and 19%, respectively. The comparisons between the observed ROx and ones modeled had implied that the current model may be overestimated the yields of peroxy radicals from the reactions of monoterpenes with ozone and an important source of peroxy radicals was possibly missed. Abnormal high concentrations of observed ROx radicals were found during high relative humidity （RH） period （especially 〉 95%）, and the possible explanation was that the humidity correction of ROx radicals under high RH conditions may be inaccurate and overestimates ROx concen-展开更多
基金supported by the National Nature Science Foundation of China(Nos.21777087 and 22276109)the Natural Science Basic Research Fund of Shaanxi Province(No.2023-JC-QN-0099)+1 种基金the Fundamental Research Funds for the Central Universities,CHD(No.300102352101)the Innovative Research Team for Science and Technology of Shaanxi Province(No.2022TD-04).
文摘Ketoprofen(KET),as a non-steroidal anti-inflammatory drug frequently detected in aqueous environments,is a threat to human health due to its accumulation and low biodegradability,which requires the transformation and degradation of KET in aqueous environments.In this paper,the reaction process of ozone-initiated KET degradation in water was investigated using density functional theory(DFT)method at the M06-2X/6-311++g(3df,2p)//M06-2X/6-31+g(d,p)level.The detailed reaction path of KET ozonation is proposed.The thermodynamic results show that ozone-initiated KET degradation is feasible.Under ultraviolet irradiation,the reaction of ozone with water can also produce OH radicals(HO·)that can react with KET.The degradation reaction of KET caused by HO·was further studied.The kinetic calculation illustrates that the reaction rate(1.99×10-1(mol/L)^(-1)sec^(-1))of KET ozonation is relatively slow,but the reaction rate of HO·reaction is relatively high,which can further improve the degradation efficiency.On this basis,the effects of pollutant concentration,ozone concentration,natural organic matter,and pH value on degradation efficiency under UV/O3 process were analyzed.The ozonolysis reaction of KET is not sensitive to pH and is basically unaffected.Finally,the toxicity prediction of oxidation compounds produced by degradation reaction indicates that most of the degradation products are harmless,and a few products containing benzene rings are still toxic and have to be concerned.This study serves as a theoretical basis for analyzing the migration and transformation process of anti-inflammatory compounds in the water environment.
基金supported by the National Natural Science Foundation of China(Nos.42177354 and 42020104001)the National Key R&D Program of China(No.2019YFC0214402)+1 种基金the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(No.2017BT01Z032)Guangdong Basic and Applied Basic Research Foundation(No.2019B151502064).
文摘Oxidation of organic amines(OAs)or aromatic hydrocarbons(AHs)produces carbonyls,which further react with OAs to form carbonyl-amine condensation products,threatening environmental quality and human health.However,there is still a lack of systematic understanding of the carbonyl-amine condensation reaction processes of OAs or between OAs and AHs,and subsequent environmental health impact.This work systematically investigated the carbonyl-amine condensation coupled ozonolysis kinetics,reaction mechanism,secondary organic aerosol(SOA)formation and cytotoxicity fromthe mixture of dipropylamine(DPA)and styrene(STY)by a combined method of productmass spectrometry identification,particle property analysis and cell exposure evaluation.The results from ozonolysis of DPA and STY mixture revealed that STY inhibited the ozonolysis of DPA to different degrees to accelerate its own decay rate.The barycenter of carbonyl-amine condensation reactionswas shifted from inside of DPA to between DPA and STY,which accelerated STY ozonolysis,but slowed down DPA ozonolysis.For the first time,ozonolysis of DPA and STY mixture to complex carbonyl-amine condensation products through the reactions of DPA with its carbonyl products,DPA with STY’s carbonyl products and DPA’s bond breakage product with STY’s carbonyl products was confirmed.These condensation products significantly contributed to the formation and growth of SOA.The SOA containing particulate carbonyl-amine condensation products showed definite cytotoxicity.These findings are helpful to deeply and comprehensively understand the transformation,fate and environmental health effects of mixed organics in atmospheric environment.
基金supported by the National Natural Science Foundation of China(Nos.92361302,22125303,92061203,and 22288201)the National Key Research and Development Program of China(No.2021YFA1400501)+2 种基金the Innovation Program for Quantum Science and Technology(No.2021ZD0303304)Dalian Institute of Chemical Physics(No.DICP DCLS201702)Chinese Academy of Sciences(No.GJJSTD20220001).
文摘Elucidating the mutual effects between the different volatile organic compounds(VOCs)is crucial for comprehending the formation mechanism of atmospheric secondary organic aerosols(SOA).Here,the mixed VOCs experiments of isoprene and△^(3)-carene/β-caryophyllene were carried out in the presence of O_(3)using an indoor smog chamber.The suppression effect of isoprene was recognized by the scanning mobility particle sizer spectrometer,online vacuum ultraviolet free electron laser(VUV-FEL)photoionization aerosol mass spectrometry,and quantum chemical calculations.The results indicate that the suppression effect of isoprene on the ozonolysis of△^(3)-carene andβ-caryophyllene shows fluctuating and monotonous trends,respectively.The carbon content of the precursor could be themain factor for regulating the strength of the suppression effect.Plausible structures and formation mechanisms of several new products generated from the single VOC precursor and VOC-cross-reaction are proposed,which enrich the category of VOC oxidation products.Meanwhile,a new dimerization mechanism of the RO_(2)+R’O_(2)reaction is suggested,which offers an intriguing perspective on the gas phase formation process of particle phase accretion products.The present findings provide valuable insights into clarifying the pivotal roles played by isoprene in the interplay between different VOCs and understanding of SOA formation mechanisms of VOC mixtures,especially nearby the emission origins.
基金supported by National Natural Science Foundation of China(No.21277082,21177076,71201093)the Promotive Research Fund for Excellent Young and Middle-aged Scientists of Shandong Province(No.BS2012HZ009,BS2012SF012)+2 种基金the Hi-Tech Research and Development Program(863)of China(No.2012AA06A301)the New Century Excellent Talents in University(NCET-13-0349)the Open Project from special fund of State Key Joint Laboratory of Environment Simulation and Pollution Control(No.13K05ESPCP)
文摘The ozonolysis of 2,3,7,8-tetra-chlorodibenzo-p-dioxin （2,3,7,8-TCDD） is an efficient degradation way in the atmosphere. The ozonolysis process and possible reactions path of Criegee Intermediates with NO and H2O are introduced in detail at the method of MPWB1K/6-31＋G（d,p）//MPWB1K/6- 311＋G（3df,2p） level. In ozonolysis, H2O is an important source of OH radical formation and initiated the subsequent degradation reaction. The Rice-Ramsperger-Kassel-Marcus （RRKM） theory was applied to calculate rate constants with the temperature ranging from 200 to 600 K. The rate constant of reaction between 2,3,7,8-TCDD and 03 is 4.80 × 10^-20 cm3/（mole.sec） at 298 K and 760 Tort. The atmospheric lifetime of the reaction species was estimated according to rate constants, which is helpful for the atmospheric model study on the degradation and risk assessment of dioxin.
基金the National Natural ScienceFundation of China (No. 20637001)
文摘An indoor chamber facility is described for investigation of atmospheric aerosol chemistry. Two sets of α-pinene ozonolysis experiments were conducted in the presence of dry ammonium sulfate seed particle: ozone limited experiments and α-pinene limited experiments. The concentration of gas phase and particle phase species was monitored continuously by on-line instruments and recorded automatically by data sampling system. The evolution of size distribution was measured by a scanning mobility particle sizer ...
基金financially supported by the National Natural Science Foundation of China(No.22125303,No.92061203,and No.21688102)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB17000000)+2 种基金Dalian Institute of Chemical Physics(DICP DCLS201701)Chinese Academy of Sciences(No.GJJSTD20190002)K.C.Wong Education Foundation(No.GJTD-2018-06)。
文摘α-pinene is the most abundant monoterpene that represents an important family of volatile organic compounds.Molecular identification of key transient compounds during theα-pinene ozonolysis has been proven to be a challenging experimental target because of a large number of intermediates and products involved.Here we exploit the recently developed hybrid instruments that integrate aerosol mass spectrometry with a vacuum ultraviolet free-electron laser to study theα-pinene ozonolysis.The experiments ofα-pinene ozonolysis are performed in an indoor smog chamber,with reactor having a volume of 2 m^(3) which is made of fluorinated ethylene propylene film.Distinct mass spectral peaks provide direct experimental signatures of previously unseen compounds produced from the reaction ofα-pinene with O_(3).With the aid of quantum chemical calculations,plausible mechanisms for the formation of these new compounds are proposed.These findings provide crucial information on fundamental understanding of the initial steps ofα-pinene oxidation and the subsequent processes of new particle formation.
基金supported by the National Natural Science Foundation of China(Nos.11575178,91544105,U1532137,91544228,and U1232130)
文摘The ozonolysis of cyclohexene is an important model system for understanding the more complex reaction of O_3 with monoterpenes; however, many previous studies have come to qualitatively different conclusions about the composition of the secondary organic aerosol(SOA)formed in this system. In the present study, the composition of the SOA produced by cyclohexene ozonolysis in the absence of seed aerosols has been investigated online and off-line using synchrotron-based thermal desorption/tunable vacuum ultraviolet photoionization time-of-flight aerosol mass spectrometry(TD-VUV-TOF-PIAMS) in conjunction with a custom-built smog chamber. On the basis of the molecular ions observed by mass spectrometry at 11.5 e V, it was found that dicarboxylic acids, dialdehydes, and cyclic anhydrides are the predominant low molecular weight components in the particle phase. The results also indicated that TD-VUV-TOF-PIAMS coupled with filter sampling is a potentially useful tool for the investigation of SOA composition both in the field and in the laboratory.
基金supported by the Ministry of Science and Technology of China(Nos.2016YFC0202700,2016YFE0112200,2014BAC22B01)the National Natural Science Foundation of China(Nos.21527814,21077025)the Marie Sklodowska Curie Actions(Nos.690958-MARSU-RISE-2015)
文摘The α-pinene ozonolysis under the different environmental conditions were observed in a smog chamber. The second-order rate constant （k） was determined to be （7.25 ± 0.06） x 10^-17 cm^3/（molecule.sec） under 20% of relative humidity （RH） and room temperature. RH showed a marked influence on the α-pinene ozonolysis. The value of k increased with KH increase, which was 1.6 times faster at RH = 80% than that at RH = 20%. Additionally, the value of k apparently changed in the presence of the aerosol particles. The diesel soot increased the k value. The fly ash prohibited the reaction, however, H2SO4-treated fly ash promoted the reaction. The information of products gained using FT-IR and SPAMS showed that pinonic acid, 10-hydroxy-pinonic acid and pinic acid could be generated during the α- pinene ozonolysis. Water molecules could take part in the formation of the products, and play a vital role in the degradation of α-pinene. The atmospheric residence time calculation showed that the ozonolysis in the atmosphere is an important way of the α-pinene consumption as compared to that reacted with OH during daytime. The results suggested that the degradation of α-pinene via the ozonization in the atmosphere may be affected greatly by RH, as well as the presence of aerosol particles. The ozonolysis reaction may be an important way of the a-pinene consumption during daytime.
文摘Some unsaturated compounds with the required （Z,Z）-double bonds configuration are synthesized through controlled ozonolysis process of 1,5,9-cyclododecatriene by determining the necessary amount of ozone passing through to selectively guarantee the breakage of a double bond while leaving other two bonds as （Z,Z）. The products were diagnosed by using NMR spectrum, infrared （IR） and mass spectrometer techniques. It is concluded that these products could widely be used in the synthesis of insect pheromones instead of insecticides and as useful intermediate compounds in many chemical reactions.
文摘Radical production in the ozonolysis of propene in air was monitored directly by a peroxy radical chemical amplification (PERCA) instrument at room temperature (298±2 K) and atmospheric pressure (1×105 Pa). The ozonolysis reactions were conducted in a flow tube under pseudo-first-order conditions for ozone. The decay in ozone was calculated based on reaction time tr and effective rate constant keff (keff = k1[C3H6]0)) for the ozone-propene reaction. The total radical yields relative to consumed ozone were determined to be 0.97±0.17 (σ). A box model was used to simulate radical production in the ozone-propene reaction. The model-derived radical yields agree well with those from experiment within the uncertainty of the two methods. In addition, the yields for OH, HO2 and CH3O2 were obtained from the measured total radical yields and radical partitioning derived from the box model. The yield is 0.39±0.08 (σ) for OH, 0.19±0.04 (σ) for HO2, and 0.39±0.08 (σ) for CH3O2. This work suggests that the previously measured radical yield by indirect method for the ozonolysis of propene may be underes-timated.
文摘The production of radicals in the ozonolysis of ethene in air in a flow tube was monitored directly by a chemical amplification instrument at room temperature （298±2） K and 1 × 10^5 Pa. The radical yield is 0.50± 0.08 （σ） and found to be independent of CO. The result shows that the indirectly measured radical yields for the ozonolysis of ethene may be underestimated by a factor of 2.
基金supported by the US National Science Foundation (CHE-1566636)UCMEXUS-CONACYT Doctoral Fellowship
文摘Cavity ring-down spectroscopy(CRDS)was utilized in combination with chemical titration with sulfur dioxide(SO_2)to quantify stabilized Criegee intermediates(s CIs)produced at low pressures(4–20 Torr)in ozonolysis reactions of cis-2-butene,2-methyl-2-butene,cyclopentene,and cyclohexene.The yield of stabilized s CI,acetaldehyde oxide(CH_3CHOO),from cis-2-butene ozonolysis decreased with decreasing pressure and reached to 0.05±0.04 at the zero-pressure limit.The nonsymmetric alkene 2-methyl-2-butene produced two stabilized s CIs,CH_3CHOO and acetone oxide((CH_3)_2COO),and their total yield decreased with decreasing pressure and reached 0.01±0.03 at the zero-pressure limit.For cyclopentene and cyclohexene,the s CI yields were essentially constant near zero,as expected of endocyclic alkenes.The nascent yields of s CI of various alkenes are compared.
基金financially supported by the National Natural Science Foundation of China (Nos.22276109,21777087,and 21876099)。
文摘Mineral aerosol particles significantly impact environmental risk prediction of liquid crystal monomers(LCMs).In this work,we investigated the reaction mechanisms and kinetics of three typical LCMs(4-cyano-3,5-difluorophenyl 4-ethylbenzoate(CEB-2F),4-cyano-3-fluorophenyl 4-ethylbenzoate(CEB-F),and 4-cyanophenyl 4-ethylbenzoate(CEB))with ozone(O_(3))in the atmospheric gas,liquid,and particle phases employing density functional theory(DFT).Here,O_(3)is prone to add to the benzene ring without F atom(s)in the selected LCMs.The ozonolysis products are aldehydes,carboxylic acids,epoxides,and unsaturated hydrocarbons containing aromatic rings.Those products undergo secondary ozonolysis to generate small molecular compounds such as glyoxal,which is beneficial for generating secondary organic aerosol(SOA).Titanium dioxide(TiO_(2)),an essential component of mineral aerosol particles,has good adsorption properties for LCMs;however,it slightly reduces the reactivity with O_(3).At 298 K,the reaction rate constant of the selected LCMs reacting with O_(3)in the gas and atmospheric liquid phases is(2.74–5.53)×10^(-24)cm^(3)/(mol·sec)and 5.58×10^(-3)–39.1 L/(mol·sec),while CEB-2F reacting with O_(3)on(TiO_(2))_(6)cluster is 1.84×10^(-24)cm^(3)/(mol·sec).The existence of TiO_(2)clusters increases the persistence and long-distance transportability of LCMs,which enlarges the contaminated area of LCMs.
基金supported by the European Commission through the 7th Framework Programme under the grant agreement #228335 (EUROCHAMP-2 Project)by the French CNRS-INSU Programme National de Chimie Atmosphrique
文摘A tunable diode laser absorption spectrometer （TDLAS） for formaldehyde atmospheric measurements has been set up and validated through comparison experiments with a Fourier transform infrared spectrometer （FT-IR） in a simulation chamber.Formaldehyde was generated in situ in the chamber from reaction of ethene with ozone.Three HCHO ro-vibrational line intensities （at 2909.71,2912.09 and 2914.46 cm-1） possibly used by TDLAS were calibrated by FT-IR spectra simultaneously recorded in the 1600–3200 cm-1 domain during ethene ozonolysis,enabling the on-line deduction of the varying concentration for HCHO in formation.The experimental line intensities values inferred confirmed the calculated ones from the updated HITRAN database.In addition,the feasibility of stratospheric in situ HCHO measurements using the 2912.09 cm-1 line was demonstrated.The TDLAS performances were also assessed,leading to a 2σ detection limit of 88 ppt in volume mixing ratio with a response time of 60 sec at 30 Torr and 294 K for 112 m optical path.As part of this work,the room-temperature rate constant of this reaction and the HCHO formation yield were found to be in excellent agreement with the compiled literature data.
文摘Synergetic effects for p-nitrophenol degradation were observed in the ozonation with ultrasonic enhancement. The enhancements of removal rate for p-nitrophenol and TOC were around 116% and 294% respectively in comparison with the individual ultrasound and ozonation systems. The synergetic phenomenon is attributed to two physicochemical mechanisms: (1) Ultrasound decomposes ozone causing augmentation of the activity of free radicals; (2) Ultrasonic wave increased the concen- tration of O3 in solution because of ultrasonic dispersion.
文摘This experimental study was carried out to verify the quality enhancement of Natural Rubber Products by drying methods and ascertain to what extent the different methods of drying affected the properties exhibited. During this study, samples of natural rubber coagulum were obtained and a sample each was subjected to one of these three methods of drying: air, smoke and oven. The qualities of the dried rubber samples from the three methods of drying were then investigated. The criterion adopted for quality in this study was Plasticity Retention Index (PRI), which gave insight of the oxidative resistance of natural rubber, a measure of quality. The plasticity retention index was tested by using the Wallace plastimeter. The PRI values were calculated for the samples. Results obtained from this study showed that the qualities of natural rubber samples were actually influenced to different measurable extents depending on drying methods, as exhibited in the PRI levels. The results further gave basis for our conclusions that the smoke dried rubber samples had the poorest qualities, having the lowest values of PRI;followed by the oven and air dried samples respectively in terms of their PRI presented the best qualities, the highest PRI values.
基金supported by the Special Funds in Marine Public Service Project of State Oceanic Administration (201005025)National High-Tech Research and Development Plan (863) of China (2007AA092101)the International Scientific and Technological Cooperation Projects(2009DFB20610)
文摘Peroxy radicals （ROx） concentrations were measured by Peroxy Radical Chemical Amplifier （PERCA） technique during the field campaign RISFEX 2003 （RiShifi Fall Experiment 2003）, which was performed in September 2003 at Rishiri island （45.07 N, 141.12 E, and 35 m asl） in the sea of Japan. The concentrations of nighttime ROx radicals had temporal variations around an average of 7.9±5.8 （1σ） pptv and showed a positive correlation with the summed mixing ratio of four monoterpene species. Model calculations suggested that local nighttime ROx radicals were dominated by the reactions of monoterpene with ozone （03） and nitrate radical （NO3）, contributing ca. 76% and 19%, respectively. The comparisons between the observed ROx and ones modeled had implied that the current model may be overestimated the yields of peroxy radicals from the reactions of monoterpenes with ozone and an important source of peroxy radicals was possibly missed. Abnormal high concentrations of observed ROx radicals were found during high relative humidity （RH） period （especially 〉 95%）, and the possible explanation was that the humidity correction of ROx radicals under high RH conditions may be inaccurate and overestimates ROx concen-
