Lead dioxide electrodes on Ti substrates were prepared by thermal-deposition or electro-deposition. The amount of hydroxyl radicals generated at the electrodes prepared by the above-mentioned two methods was compared ...Lead dioxide electrodes on Ti substrates were prepared by thermal-deposition or electro-deposition. The amount of hydroxyl radicals generated at the electrodes prepared by the above-mentioned two methods was compared with that at the electrodes mingled with Bi or La prepared by electro-deposition. The experimental results indicate that the highest concentration of hydroxyl radicals generated by thermal-deposition, electro-deposition mingled with nothing, electro-deposition mingled with Bi or La was 0.781, 1.048, 1.838 or 2.044 μmol/L, respectively. When phenol was electrolyzed on the four electrodes at a current density of 30 mA/cm2, the removal efficiency of phenol after electrolysis for 1.5 h was 87.30%, 93.55%, 97.95% or 98.70%, TOC removal efficiency after electrolysis for 5 h was 86.76%, 94.26%, 98.53% or 99.60%, respectively. Through the degradation experiments of phenol, the amount of hydroxyl radicals was responsible for the removal efficiency of phenol. The electro-catalytic characteristics were investigated by SEM, the generation amount of hydroxyl radicals, the degradation degree of phenol and the stability and conductivity of the electrodes were also investigated. The experimental results indicate that the four electrodes all show good electro-catalytic characteristics; the electro-catalytic characteristics of the electrode mingled with La were superior to those of the other three ones, and the electrochemical degradation of phenol followed one-step reaction dynamics.展开更多
Basing on the DFT calculations we propose the new theoretical model which describes both the surface tension σ of the short chain n-alkanes at their normal boiling points and their reaction rate constants with hydrox...Basing on the DFT calculations we propose the new theoretical model which describes both the surface tension σ of the short chain n-alkanes at their normal boiling points and their reaction rate constants with hydroxyl radicals OH<span style="white-space:nowrap;">•</span> (at 297 ± 2 K) on the basis of their molecular orbital electronic characteristics. It has been shown that intermolecular dispersion attraction within the surface liquid monolayer of these compounds, as well as their reaction rate constants k with OH<span style="white-space:nowrap;">•</span> radicals are determined by the energies <em>E<sub>orb</sub></em> of the specific occupied molecular orbitals which are the same in the determination of both the above physico-chemical characteristics of the studied n-alkanes. The received regression equations confirm the theoretically found dependences between the quantities of σ and k and the module |<em>E<sub>orb</sub></em>|. For the compounds under study this fact indicates the key role of their electronic structure particularities in determination of both the physical (surface tension) and the chemical (reaction rate constants) properties.展开更多
Effects of discharge mode, voltage applied, size of the nozzle discharge electrode and flow rate of water on the generation of hydroxyl radical were investigated in air discharge with atomized water, by using optical ...Effects of discharge mode, voltage applied, size of the nozzle discharge electrode and flow rate of water on the generation of hydroxyl radical were investigated in air discharge with atomized water, by using optical emission spectroscopy (OES). Water was injected into the discharge region through the discharge nozzle electrode, and a large amount of fine water drops, formed and distributed in the discharge region, corona discharge was more effective to generate were observed. It was found that negative DC the hydroxyl radicals in comparison to positive DC corona discharge or negative pulsed discharge. A larger outer diameter of the nozzle electrode or a stronger electric field is beneficial for hydroxyl-radical generation. Moreover, there is a critical value in the flow rate of atomized water against the discharge voltage. Below this critical value, hydroxyl-radical generation increases with the increase in flow rate of the water, while above this value, it decreases. In addition, it is observed that OES from the discharge is mainly in the ultraviolet domain. The results are helpful in the study of the mechanism and application of plasma in pollution-control in either air or water.展开更多
Rate constants for the reaction of hydroxyl radicals with HFC 134a (CH 2FCF 3) have been measured by the discharge flow resonance fluorescence (DF RF) technique over the temperature range 288—370 K. The derived Arrhe...Rate constants for the reaction of hydroxyl radicals with HFC 134a (CH 2FCF 3) have been measured by the discharge flow resonance fluorescence (DF RF) technique over the temperature range 288—370 K. The derived Arrhenius equation is: k″ =(1.27±0.16)×10 -12 exp(-(1662±41)/ T )cm 3/(mol·s). The tropospheric lifetime of HFC 134a is estimated to be 10.5 years, which is in excellent agreement with the most recent results.展开更多
With the physical method of micro-gap gas discharge, OH. radicals were produced by the ionization of O2 in air and H2O in the gaseous state, in order to explore more effective method totreat the ship's ballast water....With the physical method of micro-gap gas discharge, OH. radicals were produced by the ionization of O2 in air and H2O in the gaseous state, in order to explore more effective method totreat the ship's ballast water. The surface morphology of Al2O3 dielectric layer was analysed using Atomic Force Microscopy (AFM), where the size of Al2O3 particles was in the range of 2 μm to 5 μm. At the same time, the biochemical effect of hydroxyl radicals on the introduced organisms and the quality of ship's ballast water were studied. The results indicate that the main reasons of cell death are lipid peroxide and damage of the antioxidant enzyme system in Catalase (CAT), Peroxidase (POD) and Superoxide dismutase (SOD). In addition, the quality of the ballast water was greatly improved.展开更多
The qualitative and quantitative analyses of reactive oxygen species are essential to determine their steady-state concentration and related reaction mechanisms in environmental aquatic systems. In this study, salicyl...The qualitative and quantitative analyses of reactive oxygen species are essential to determine their steady-state concentration and related reaction mechanisms in environmental aquatic systems. In this study, salicylic acid was employed as an innovative molecular probe of hydroxyl radical(OH) generated in aqueous nitrate and nitrite solutions through photochemical reactions. Kinetic studies showed that the steady-state concentrations of OH in aqueous NO- 3(10 mmol/L, pH=5) and NO- 2(10 mmol/L, pH=5) solutions under ultraviolet irradiation were at a same magnitude, 10 -15 mol/L. Apparent quantum yields of OH at 313 nm were measured as 0.011 and 0.07 for NO- 3 and NO- 2 respectively, all comparable to the results of previous studies.展开更多
A new method of determining the cumulate concentration of hydroxyl radicals in the TiO2/Ti photoelectrocatalytic(PEC) oxidation system was established by o-phenanthroline-Fe(Ⅱ)(Fe(phen)3^2+) spectrophotometr...A new method of determining the cumulate concentration of hydroxyl radicals in the TiO2/Ti photoelectrocatalytic(PEC) oxidation system was established by o-phenanthroline-Fe(Ⅱ)(Fe(phen)3^2+) spectrophotometry and using anion exchange membrane. Fe (phen)3^2+ can be oxidized to o-phenanthroline-Fe(Ⅲ)(Fe(phen)3^3+) by strong oxidization of hydroxyl radicals(·OH). Then the cumulate concentration of hydroxyl radicals can be calculated through determining the change of the Fe(phen)3^3+ absorbency at 509 nm. In addition, the research results showed the production rate of hydroxyl radicals was affected obviously by pH of solution, the cumulate concentration of hydroxyl radicals was the largest at nearby the initial pH 6.3 (isoelectric point), and the change direction of pH after illumination tended to nearby isoelectric point.展开更多
Hydroxyl radicals play the key role during electrochemical oxidation and photoelectrochemical oxidation. The production and effect of hydroxyl radicals on the interface between DSA anode and water was investigated by ...Hydroxyl radicals play the key role during electrochemical oxidation and photoelectrochemical oxidation. The production and effect of hydroxyl radicals on the interface between DSA anode and water was investigated by examining the quenching effect of iso-propanol on Orange II decolorization. We observed that with an increase in electrode potential from 4 to 12 V across electrodes at pH 7.0, the contribution percentage of hydroxyl radicals increased dramatically. More OH radicals were produced in acidic and alkaline conditions than at neutral conditions. At electrode potential of 4 V, the contribution percentage of hydroxyl radicals was obviously higher at near neutral pH conditions, while removal efficiency of Orange/I achieved was the lowest concurrently. Finally, for photocatalytic oxidation, electrochemical oxidation, and photoelectrochemical oxidation using the same DSA electrode, the effect of hydroxyl radicals proved to be dominant in photocatalytic oxidation but the contribution of hydroxyl radicals was not dominant in electrochemical oxidation, which implies the necessity of UV irradiation for electrochemical oxidation during water treatment.展开更多
This study investigated the indirect oxidation of nitrobenzene(NB)by hydroxyl radicals(·OH)in a rotating packed bed(RPB)using competitive kinetics method with p-nitrochlorobenzene as a reference compound.The rate...This study investigated the indirect oxidation of nitrobenzene(NB)by hydroxyl radicals(·OH)in a rotating packed bed(RPB)using competitive kinetics method with p-nitrochlorobenzene as a reference compound.The rate constants of NB with·OH are calculated to be between(1.465±0.113)×10^(9)L/(mol·s)and(2.497±0.192)×10^(9)L/(mol·s).The experimental data are fitted by the modified Arrhenius equation,where the activation energy is 4877.74 J/mol,the order of NB concentration,rotation speed,and initial pH is 0.2425,0.1400 and 0.0167,respectively.The ozonation process of NB could be enhanced by RPB,which is especially effective for highly concentrated NB-containing waste-water under alkaline conditions.The high gravity technology can accelerate ozone mass transfer and self-decomposition of ozone to produce more·OH,resulting in an increase in the indirect oxidation rate of NB by·OH and consequently effective degradation of NB in wastewater.展开更多
<Abstract>In order to explore the production of hydroxyl radical(·OH)in a confined space,a novel ozone-light irradiation system is constructed in this study,and the·OH radical is measured by spin-trapp...<Abstract>In order to explore the production of hydroxyl radical(·OH)in a confined space,a novel ozone-light irradiation system is constructed in this study,and the·OH radical is measured by spin-trapping electron spin resonance(ESR)method in which 5,5-dimethyl-1-pyrroline-N-oxide(DMPO)is selected as the spin-trap.Several influence factors including the light intensity,the irradiation time and DMPO mass concentration are discussed. The results show that in this experimental system,with DMPO mass concentration of 1g/L and the irradiation time of 30 min,the·OH radical can be best captured.Besides,both wavelength and intensity of the irradiation light could effect the generation of·OH radical.These results are of great importance to further study the sterilization effect of·OH radical in confined space.展开更多
Excessive reactive oxygen species(ROS)would attack living cells and cause a series of oxidative stress related diseases,such as liver damage.Hydroxyl radicals(·OH)are currently known as one of the most toxic and ...Excessive reactive oxygen species(ROS)would attack living cells and cause a series of oxidative stress related diseases,such as liver damage.Hydroxyl radicals(·OH)are currently known as one of the most toxic and harmful free radicals to organisms.Therefore,studies involving hydroxyl radicals have become important research topics in the fields of biology,biochemistry,and biomedicine.In addition,imaging of analytes using upconversion nanoparticles(UCNPs)possesses significant advantages over that using general fluorescent dyes or nanoparticles due to its high spatial resolution,reduced photodamage,and deep tissue penetration properties.Herein,we designed a highly selective and sensitive hydroxyl radical nanoprobe based on the luminescence resonance energy transfer between upconversion nanoparticles and methylene blue(MB).The concentration of·OH could be determined by the fluorescence recovery of the UCNPs due to the oxidative damage of MB.Using this nanoprobe,the·OH in living cells or in liver tissues could be monitored with high sensitivity and selectivity.展开更多
Ozonation has been proved to be a promising approach for eliminating emerging pollutants in wastewater.In previous studies,emerging pollutants including diverse pharmaceuticals were found to exhibit significantly diff...Ozonation has been proved to be a promising approach for eliminating emerging pollutants in wastewater.In previous studies,emerging pollutants including diverse pharmaceuticals were found to exhibit significantly different ozonation reactivity.However,how the structural differences of emerging pollutants determine ozonation reactivity and mechanisms are still ambiguous.In this work,ozonation of dimethylaminophenazone(DMP)and acetylaminophenazone(AAA)with the same parent structure of phenazone but different substitution groups was investigated,in order to probe influencing mechanisms of structural differences on ozonation reactivity.Results show that DMP reacts with ozone and HOalmost 2 and 1 order of magnitude faster than AAA,respectively.At pH 8,HO· accelerates ozonation of DMP,but decreases ozonation of AAA.Competition simultaneously decreases degradation rate of the two phenazones,but effects on AAA are more significant than that on DMP.According to theoretical calculation results,differences in ozonation reactivity and mechanisms of the two phenazones can be mainly attributed to different substitution groups.The dimethylamino group in the structure of DMP increases the ozonation reactivity of phenazone by increasing reaction orbital energies and altering reaction sites,while the acetylamino group in the structure of AAA decreases the reaction orbital energy and therefore lowers the reactivity.展开更多
In an aqueous solution, normal electrolysis at high voltages switches over spontaneously to glow discharge electrolysis and gives rise to hydroxyl radical, hydrogen peroxide, and aqueous electron, as well as several o...In an aqueous solution, normal electrolysis at high voltages switches over spontaneously to glow discharge electrolysis and gives rise to hydroxyl radical, hydrogen peroxide, and aqueous electron, as well as several other active species. Hydroxyl radical directly attacks organic contaminants to make them oxidized. In the present paper, 2-naphthylamine is eventually degraded into hydrogen carbonate and carbon dioxide. The degradation process is analyzed by using an Ultraviolet (UV) absorption spectrum, high-performance liquid chromatography (HPLC) and chemical oxygen demand (COD). It is demonstrated that 2-naphthylamine (co =30 mg·1-1) is completely converted within 2h at 30℃ and 600 V by glow discharge electrolysis, and the degradation is strongly dependent upon the presence of ferrous ions. COD is ascended in the absence of ferrous ions and descended in the presence of them.展开更多
[Objectives]To study the optimum conditions of solid fermentation of natto with antioxidant function as an index.[Methods]Single factor experiment and orthogonal experiment were designed to study the effects of temper...[Objectives]To study the optimum conditions of solid fermentation of natto with antioxidant function as an index.[Methods]Single factor experiment and orthogonal experiment were designed to study the effects of temperature,time,initial pH and inoculum amount on the antioxidant activity of natto solid fermentation.The optimum conditions of natto solid fermentation were determined and the antioxidant ac-tivity of natto extract was compared.[Results]The optimal fermentation conditions were as follows:temperature 32℃,initial pH 7.0,inocu-lation amount 8%,fermentation time 32 h.The hydroxyl radical scavenging rate of natto solid fermentation crude extract was the highest,which was 82.7%.The optimized nato fermentation extract showed stronger scavenging ability for-OH and O,:,and showed obvious dose-effect relationship.ICso was 3.63 and 4.24 mg/mL,respectively,and the scavenging efficiency was 1.3 and 1.9 times higher than that of the unoptimized fermentation extract,respectively.[Conclusions]Natto is rich in nattokinase and other functional factors,and its antioxidant ac-tivity can be improved by optimizing fermentation technology,so that natto products can be widely used,including cosmetic raw materials,nat-to skin care soap,health food and medicine,etc.,and have a broader development prospect.展开更多
The hydroxyl radical (·OH) plays a central role in the oxidation and removal of many atmospheric compounds. Measurement of atmospheric ·OH is very difficult because of its high reactivity and low atmospher...The hydroxyl radical (·OH) plays a central role in the oxidation and removal of many atmospheric compounds. Measurement of atmospheric ·OH is very difficult because of its high reactivity and low atmospheric abundance. In this article, a simple and highly sensitive method, high performance liquid chromatography coupled with coulometric detection (HPLC-CD), was developed to determine ·OH indirectly by determining its reaction products with salicylic acid (SAL), 2,3-dihydroxybenzoic acid (2,3-DHBA), and 2,5-dihydroxybenzoic acid (2,5-DHBA). Under the optimum conditions for its determination, 2,3-DHBA and 2,5-DHBA could be well separated and the detection limits for 2,3-DHBA were 3 ×10^-10 mol/L and for 2,5-DHBA were 1.5 ×10^-10 mol/L, which were lower than most previous reports. This method was also applied to measure atmospheric hydroxyl radical levels and demonstrated the feasibility in clean and polluted air.展开更多
A light purple organic active substance capable of scavenging hydroxyl radical(OH) with a high efficiency was extracted from Oyster shell at an extraction rate of 2.49%. It was found for the first time that this act...A light purple organic active substance capable of scavenging hydroxyl radical(OH) with a high efficiency was extracted from Oyster shell at an extraction rate of 2.49%. It was found for the first time that this active substance may scavenge OH with the efficiency far higher than that of vitamin C. This active substance may scavenge also superoxide radical(O2) although the scavenging efficiency is far lower than that of vitamin C. Infrared spectrometry and routine chemical analysis primarily reveal that this active substance belongs to glycoprotein.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
Ab initio and density functional theory calculations have been carried out to investigate the reaction of hydroxyl radical (OH) and 1,1,1-trichloroethane (CH3CCl3). The potential energy surface has been given acco...Ab initio and density functional theory calculations have been carried out to investigate the reaction of hydroxyl radical (OH) and 1,1,1-trichloroethane (CH3CCl3). The potential energy surface has been given according to the relative energies calculated at the MP2/cc-pVTZ level after the spin projection (PMP2). Five reaction channels were identified and the intramolecular hydrogen bonding was observed in some transition state structures. The barrier heights and reaction enthalpies calculated for all possible channels show that the hydrogen abstraction channel is predominant kinetically and thermodynamically. The contribution from other channels was predicted to be minor.展开更多
[Objectives] The aim of this work was to compare the inhibitory effects of different water-soluble extracts of ginseng on hydroxyl radical. [Methods]The water-soluble effective parts of ginseng were extracted by ortho...[Objectives] The aim of this work was to compare the inhibitory effects of different water-soluble extracts of ginseng on hydroxyl radical. [Methods]The water-soluble effective parts of ginseng were extracted by orthogonal test,the hydroxyl radical scavenging rate of each extract was determined by salicylic acid method,and the extraction process of the optimum hydroxyl radical inhibitor was optimized using variance analysis and cluster analysis. [Results] A total of 16 samples were prepared. Among them,the sample No. 12 had the highest hydroxyl radical scavenging rate,and the inhibition rate reached 105. 08% at the concentration of 1 g/L. [Conclusions] Ginseng water extract contained hydroxyl radical scavenger,of which the optimum extraction process was as follows: p H of 8,solid to liquid ratio of 1∶ 10,extraction temperature of 4℃,extraction time of 12 h and extraction times of 3.展开更多
基金the Environment Bureau of Jilin Province, China(No.2006-11)Scientific Institute of Changchun City(No. 2007KZ15)985 Project of Jilin University
文摘Lead dioxide electrodes on Ti substrates were prepared by thermal-deposition or electro-deposition. The amount of hydroxyl radicals generated at the electrodes prepared by the above-mentioned two methods was compared with that at the electrodes mingled with Bi or La prepared by electro-deposition. The experimental results indicate that the highest concentration of hydroxyl radicals generated by thermal-deposition, electro-deposition mingled with nothing, electro-deposition mingled with Bi or La was 0.781, 1.048, 1.838 or 2.044 μmol/L, respectively. When phenol was electrolyzed on the four electrodes at a current density of 30 mA/cm2, the removal efficiency of phenol after electrolysis for 1.5 h was 87.30%, 93.55%, 97.95% or 98.70%, TOC removal efficiency after electrolysis for 5 h was 86.76%, 94.26%, 98.53% or 99.60%, respectively. Through the degradation experiments of phenol, the amount of hydroxyl radicals was responsible for the removal efficiency of phenol. The electro-catalytic characteristics were investigated by SEM, the generation amount of hydroxyl radicals, the degradation degree of phenol and the stability and conductivity of the electrodes were also investigated. The experimental results indicate that the four electrodes all show good electro-catalytic characteristics; the electro-catalytic characteristics of the electrode mingled with La were superior to those of the other three ones, and the electrochemical degradation of phenol followed one-step reaction dynamics.
文摘Basing on the DFT calculations we propose the new theoretical model which describes both the surface tension σ of the short chain n-alkanes at their normal boiling points and their reaction rate constants with hydroxyl radicals OH<span style="white-space:nowrap;">•</span> (at 297 ± 2 K) on the basis of their molecular orbital electronic characteristics. It has been shown that intermolecular dispersion attraction within the surface liquid monolayer of these compounds, as well as their reaction rate constants k with OH<span style="white-space:nowrap;">•</span> radicals are determined by the energies <em>E<sub>orb</sub></em> of the specific occupied molecular orbitals which are the same in the determination of both the above physico-chemical characteristics of the studied n-alkanes. The received regression equations confirm the theoretically found dependences between the quantities of σ and k and the module |<em>E<sub>orb</sub></em>|. For the compounds under study this fact indicates the key role of their electronic structure particularities in determination of both the physical (surface tension) and the chemical (reaction rate constants) properties.
基金supported by Science and Technology Commission of Shanghai Municipality of China(No.09ZR1421200)Shanghai Maritime University of China(No.2008462)
文摘Effects of discharge mode, voltage applied, size of the nozzle discharge electrode and flow rate of water on the generation of hydroxyl radical were investigated in air discharge with atomized water, by using optical emission spectroscopy (OES). Water was injected into the discharge region through the discharge nozzle electrode, and a large amount of fine water drops, formed and distributed in the discharge region, corona discharge was more effective to generate were observed. It was found that negative DC the hydroxyl radicals in comparison to positive DC corona discharge or negative pulsed discharge. A larger outer diameter of the nozzle electrode or a stronger electric field is beneficial for hydroxyl-radical generation. Moreover, there is a critical value in the flow rate of atomized water against the discharge voltage. Below this critical value, hydroxyl-radical generation increases with the increase in flow rate of the water, while above this value, it decreases. In addition, it is observed that OES from the discharge is mainly in the ultraviolet domain. The results are helpful in the study of the mechanism and application of plasma in pollution-control in either air or water.
文摘Rate constants for the reaction of hydroxyl radicals with HFC 134a (CH 2FCF 3) have been measured by the discharge flow resonance fluorescence (DF RF) technique over the temperature range 288—370 K. The derived Arrhenius equation is: k″ =(1.27±0.16)×10 -12 exp(-(1662±41)/ T )cm 3/(mol·s). The tropospheric lifetime of HFC 134a is estimated to be 10.5 years, which is in excellent agreement with the most recent results.
基金supported by the Key Project of National Support Plan from Science and Technology Ministry of China (2006BAC11B06) the Key Project of International Cooperation from the Ministry of Science and Technology of China (2005DFA20800)+1 种基金the Support Plan of National New Century Excellent Youth of China (NCET-04-0286, -05-0398) the Project of National Natural Science Foundation of China (No. 60371035)
文摘With the physical method of micro-gap gas discharge, OH. radicals were produced by the ionization of O2 in air and H2O in the gaseous state, in order to explore more effective method totreat the ship's ballast water. The surface morphology of Al2O3 dielectric layer was analysed using Atomic Force Microscopy (AFM), where the size of Al2O3 particles was in the range of 2 μm to 5 μm. At the same time, the biochemical effect of hydroxyl radicals on the introduced organisms and the quality of ship's ballast water were studied. The results indicate that the main reasons of cell death are lipid peroxide and damage of the antioxidant enzyme system in Catalase (CAT), Peroxidase (POD) and Superoxide dismutase (SOD). In addition, the quality of the ballast water was greatly improved.
文摘The qualitative and quantitative analyses of reactive oxygen species are essential to determine their steady-state concentration and related reaction mechanisms in environmental aquatic systems. In this study, salicylic acid was employed as an innovative molecular probe of hydroxyl radical(OH) generated in aqueous nitrate and nitrite solutions through photochemical reactions. Kinetic studies showed that the steady-state concentrations of OH in aqueous NO- 3(10 mmol/L, pH=5) and NO- 2(10 mmol/L, pH=5) solutions under ultraviolet irradiation were at a same magnitude, 10 -15 mol/L. Apparent quantum yields of OH at 313 nm were measured as 0.011 and 0.07 for NO- 3 and NO- 2 respectively, all comparable to the results of previous studies.
文摘A new method of determining the cumulate concentration of hydroxyl radicals in the TiO2/Ti photoelectrocatalytic(PEC) oxidation system was established by o-phenanthroline-Fe(Ⅱ)(Fe(phen)3^2+) spectrophotometry and using anion exchange membrane. Fe (phen)3^2+ can be oxidized to o-phenanthroline-Fe(Ⅲ)(Fe(phen)3^3+) by strong oxidization of hydroxyl radicals(·OH). Then the cumulate concentration of hydroxyl radicals can be calculated through determining the change of the Fe(phen)3^3+ absorbency at 509 nm. In addition, the research results showed the production rate of hydroxyl radicals was affected obviously by pH of solution, the cumulate concentration of hydroxyl radicals was the largest at nearby the initial pH 6.3 (isoelectric point), and the change direction of pH after illumination tended to nearby isoelectric point.
基金supported by the National Natural Science Foundation of China (No. 50708037)the Starting Fund for Talents of North China University of Water Conservancy and Electric Power
文摘Hydroxyl radicals play the key role during electrochemical oxidation and photoelectrochemical oxidation. The production and effect of hydroxyl radicals on the interface between DSA anode and water was investigated by examining the quenching effect of iso-propanol on Orange II decolorization. We observed that with an increase in electrode potential from 4 to 12 V across electrodes at pH 7.0, the contribution percentage of hydroxyl radicals increased dramatically. More OH radicals were produced in acidic and alkaline conditions than at neutral conditions. At electrode potential of 4 V, the contribution percentage of hydroxyl radicals was obviously higher at near neutral pH conditions, while removal efficiency of Orange/I achieved was the lowest concurrently. Finally, for photocatalytic oxidation, electrochemical oxidation, and photoelectrochemical oxidation using the same DSA electrode, the effect of hydroxyl radicals proved to be dominant in photocatalytic oxidation but the contribution of hydroxyl radicals was not dominant in electrochemical oxidation, which implies the necessity of UV irradiation for electrochemical oxidation during water treatment.
基金the Specialized Research Fund for Sanjin Scholars Program of Shanxi Province(No.201707)Key Research&Development Plan of Shanxi Province(No.201903D321059)+1 种基金Shanxi Scholarship Council of China(No.HGKY2019071)Transformation and Cultivation Projects of Scientific and Technological Achievements of Higher Education Institutions for Shanxi Province(No.2020CG040).
文摘This study investigated the indirect oxidation of nitrobenzene(NB)by hydroxyl radicals(·OH)in a rotating packed bed(RPB)using competitive kinetics method with p-nitrochlorobenzene as a reference compound.The rate constants of NB with·OH are calculated to be between(1.465±0.113)×10^(9)L/(mol·s)and(2.497±0.192)×10^(9)L/(mol·s).The experimental data are fitted by the modified Arrhenius equation,where the activation energy is 4877.74 J/mol,the order of NB concentration,rotation speed,and initial pH is 0.2425,0.1400 and 0.0167,respectively.The ozonation process of NB could be enhanced by RPB,which is especially effective for highly concentrated NB-containing waste-water under alkaline conditions.The high gravity technology can accelerate ozone mass transfer and self-decomposition of ozone to produce more·OH,resulting in an increase in the indirect oxidation rate of NB by·OH and consequently effective degradation of NB in wastewater.
文摘<Abstract>In order to explore the production of hydroxyl radical(·OH)in a confined space,a novel ozone-light irradiation system is constructed in this study,and the·OH radical is measured by spin-trapping electron spin resonance(ESR)method in which 5,5-dimethyl-1-pyrroline-N-oxide(DMPO)is selected as the spin-trap.Several influence factors including the light intensity,the irradiation time and DMPO mass concentration are discussed. The results show that in this experimental system,with DMPO mass concentration of 1g/L and the irradiation time of 30 min,the·OH radical can be best captured.Besides,both wavelength and intensity of the irradiation light could effect the generation of·OH radical.These results are of great importance to further study the sterilization effect of·OH radical in confined space.
基金the support from the National Natural Science Foundation of China(21601046,31500812,and 21603051)the Natural Science Foundation of Hebei Province(B2016201169,B2017201226,B2018201221,and B2018201157)+2 种基金Key Projects of Education Department of Hebei Province(ZD2018036)the Foundation for Returned Overseas Chinese Scholars of Hebei Province(CY201703)Hebei Youth Top Talent Project.
文摘Excessive reactive oxygen species(ROS)would attack living cells and cause a series of oxidative stress related diseases,such as liver damage.Hydroxyl radicals(·OH)are currently known as one of the most toxic and harmful free radicals to organisms.Therefore,studies involving hydroxyl radicals have become important research topics in the fields of biology,biochemistry,and biomedicine.In addition,imaging of analytes using upconversion nanoparticles(UCNPs)possesses significant advantages over that using general fluorescent dyes or nanoparticles due to its high spatial resolution,reduced photodamage,and deep tissue penetration properties.Herein,we designed a highly selective and sensitive hydroxyl radical nanoprobe based on the luminescence resonance energy transfer between upconversion nanoparticles and methylene blue(MB).The concentration of·OH could be determined by the fluorescence recovery of the UCNPs due to the oxidative damage of MB.Using this nanoprobe,the·OH in living cells or in liver tissues could be monitored with high sensitivity and selectivity.
基金supported by the National High Technology Research and Development of China(No.2013AA06A305)Program for Changjiang Scholars and Innovative Research Team in University,China Postdoctoral Science Foundation(2013T60128)Hundreds Talents Program of Chinese Academy of Sciences.
文摘Ozonation has been proved to be a promising approach for eliminating emerging pollutants in wastewater.In previous studies,emerging pollutants including diverse pharmaceuticals were found to exhibit significantly different ozonation reactivity.However,how the structural differences of emerging pollutants determine ozonation reactivity and mechanisms are still ambiguous.In this work,ozonation of dimethylaminophenazone(DMP)and acetylaminophenazone(AAA)with the same parent structure of phenazone but different substitution groups was investigated,in order to probe influencing mechanisms of structural differences on ozonation reactivity.Results show that DMP reacts with ozone and HOalmost 2 and 1 order of magnitude faster than AAA,respectively.At pH 8,HO· accelerates ozonation of DMP,but decreases ozonation of AAA.Competition simultaneously decreases degradation rate of the two phenazones,but effects on AAA are more significant than that on DMP.According to theoretical calculation results,differences in ozonation reactivity and mechanisms of the two phenazones can be mainly attributed to different substitution groups.The dimethylamino group in the structure of DMP increases the ozonation reactivity of phenazone by increasing reaction orbital energies and altering reaction sites,while the acetylamino group in the structure of AAA decreases the reaction orbital energy and therefore lowers the reactivity.
基金The project supported in part by the Project of Key Science and Technology of Education Ministry (00250)the Nature Science Foundation of Gansu Province (3ZS041-A25-028)the Invention Project of Science and Technology (KJCXGC-01, NWNU), 2000
文摘In an aqueous solution, normal electrolysis at high voltages switches over spontaneously to glow discharge electrolysis and gives rise to hydroxyl radical, hydrogen peroxide, and aqueous electron, as well as several other active species. Hydroxyl radical directly attacks organic contaminants to make them oxidized. In the present paper, 2-naphthylamine is eventually degraded into hydrogen carbonate and carbon dioxide. The degradation process is analyzed by using an Ultraviolet (UV) absorption spectrum, high-performance liquid chromatography (HPLC) and chemical oxygen demand (COD). It is demonstrated that 2-naphthylamine (co =30 mg·1-1) is completely converted within 2h at 30℃ and 600 V by glow discharge electrolysis, and the degradation is strongly dependent upon the presence of ferrous ions. COD is ascended in the absence of ferrous ions and descended in the presence of them.
基金Supported by 2023 Zhanjiang Non-funded Science and Technology Research Plan(2023B01023)2022 University-level Education and Teaching Reform Project of Lingnan Normal University(LingShiJiaoWu2022154).Junxia SONG,bachelor degree,experimenter,research fields:physical geography.
文摘[Objectives]To study the optimum conditions of solid fermentation of natto with antioxidant function as an index.[Methods]Single factor experiment and orthogonal experiment were designed to study the effects of temperature,time,initial pH and inoculum amount on the antioxidant activity of natto solid fermentation.The optimum conditions of natto solid fermentation were determined and the antioxidant ac-tivity of natto extract was compared.[Results]The optimal fermentation conditions were as follows:temperature 32℃,initial pH 7.0,inocu-lation amount 8%,fermentation time 32 h.The hydroxyl radical scavenging rate of natto solid fermentation crude extract was the highest,which was 82.7%.The optimized nato fermentation extract showed stronger scavenging ability for-OH and O,:,and showed obvious dose-effect relationship.ICso was 3.63 and 4.24 mg/mL,respectively,and the scavenging efficiency was 1.3 and 1.9 times higher than that of the unoptimized fermentation extract,respectively.[Conclusions]Natto is rich in nattokinase and other functional factors,and its antioxidant ac-tivity can be improved by optimizing fermentation technology,so that natto products can be widely used,including cosmetic raw materials,nat-to skin care soap,health food and medicine,etc.,and have a broader development prospect.
基金This work was supported by the National Natural Science Foundation of China(No.40075026).
文摘The hydroxyl radical (·OH) plays a central role in the oxidation and removal of many atmospheric compounds. Measurement of atmospheric ·OH is very difficult because of its high reactivity and low atmospheric abundance. In this article, a simple and highly sensitive method, high performance liquid chromatography coupled with coulometric detection (HPLC-CD), was developed to determine ·OH indirectly by determining its reaction products with salicylic acid (SAL), 2,3-dihydroxybenzoic acid (2,3-DHBA), and 2,5-dihydroxybenzoic acid (2,5-DHBA). Under the optimum conditions for its determination, 2,3-DHBA and 2,5-DHBA could be well separated and the detection limits for 2,3-DHBA were 3 ×10^-10 mol/L and for 2,5-DHBA were 1.5 ×10^-10 mol/L, which were lower than most previous reports. This method was also applied to measure atmospheric hydroxyl radical levels and demonstrated the feasibility in clean and polluted air.
基金Supported by the Natural Science Foundation of Fujian Province, China(NoC0510029)the Specialized Foundation for Creative Team of Young and Middle-aged Teachers of Jimei University, China(No2006A003)
文摘A light purple organic active substance capable of scavenging hydroxyl radical(OH) with a high efficiency was extracted from Oyster shell at an extraction rate of 2.49%. It was found for the first time that this active substance may scavenge OH with the efficiency far higher than that of vitamin C. This active substance may scavenge also superoxide radical(O2) although the scavenging efficiency is far lower than that of vitamin C. Infrared spectrometry and routine chemical analysis primarily reveal that this active substance belongs to glycoprotein.
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 Natural Science Foundation of China (No. 20573029)the Natural Science Foundation of Heilongjiang Province (No. B200905)
文摘Ab initio and density functional theory calculations have been carried out to investigate the reaction of hydroxyl radical (OH) and 1,1,1-trichloroethane (CH3CCl3). The potential energy surface has been given according to the relative energies calculated at the MP2/cc-pVTZ level after the spin projection (PMP2). Five reaction channels were identified and the intramolecular hydrogen bonding was observed in some transition state structures. The barrier heights and reaction enthalpies calculated for all possible channels show that the hydrogen abstraction channel is predominant kinetically and thermodynamically. The contribution from other channels was predicted to be minor.
基金Supported by Open Foundation of Key Laboratory of Ministry of Education for TCM Viscera-State Theory and Applications,Liaoning University of Traditional Chinese Medicine(ZYZX1709)Project of Education Department of Liaoning Province(L201606)China Postdoctoral Science Foundation(2013M530945)
文摘[Objectives] The aim of this work was to compare the inhibitory effects of different water-soluble extracts of ginseng on hydroxyl radical. [Methods]The water-soluble effective parts of ginseng were extracted by orthogonal test,the hydroxyl radical scavenging rate of each extract was determined by salicylic acid method,and the extraction process of the optimum hydroxyl radical inhibitor was optimized using variance analysis and cluster analysis. [Results] A total of 16 samples were prepared. Among them,the sample No. 12 had the highest hydroxyl radical scavenging rate,and the inhibition rate reached 105. 08% at the concentration of 1 g/L. [Conclusions] Ginseng water extract contained hydroxyl radical scavenger,of which the optimum extraction process was as follows: p H of 8,solid to liquid ratio of 1∶ 10,extraction temperature of 4℃,extraction time of 12 h and extraction times of 3.