The apparent sulfur oxidation activities of four pure thermophilic archaea, Acidianus brierleyi （JCM 8954）, Metallosphaera sedula （YN 23）, Acidianus manzaensis （YN 25） and Sulfolobus metallicus （YN 24） and the...The apparent sulfur oxidation activities of four pure thermophilic archaea, Acidianus brierleyi （JCM 8954）, Metallosphaera sedula （YN 23）, Acidianus manzaensis （YN 25） and Sulfolobus metallicus （YN 24） and their mixture in bioleaching chalcopyrite were compared, which were characterized indirectly by the evolution of the cells concentration, pH value and sulfate ions concentration in solution. The results show that the mixed culture contributed significantly to the raising of leaching rate, which suggests that the mixed culture had a higher sulfur oxidation activity than the pure culture. Meanwhile, the results also indicate that the changes of parameters characterizing the sulfur oxidation activity of thermophilic archaea are often influenced by many factors, so it is hard to reflect accurately the specific sulfur oxidation activities among the different sulfur-oxidizing microbes when bioleaching chalcopyrite at different conditions. Accordingly, an efficient method to characterize microbial sulfur oxidation activity appears to be desirable.展开更多
The effects of chloride anion （Cl-） （up to 1.0 mol/L） on the decolorization of a model compound,azo dye Acid Orange 7 （AO7）,by sulfate radical （SO4-） based-peroxydisulfate （PS） or peroxymonosulfate （PMS） o...The effects of chloride anion （Cl-） （up to 1.0 mol/L） on the decolorization of a model compound,azo dye Acid Orange 7 （AO7）,by sulfate radical （SO4-） based-peroxydisulfate （PS） or peroxymonosulfate （PMS） oxidation under various activated conditions （UV 254 nm /PS,Thermal （70°C/PS,UV 254 nm /PMS,Co 2＋ /PMS） were investigated.Methanol and NH4 ＋ were used as quenching reagents to determine the contributions of active chlorine species （dichloride radical （Cl2-.） and hypochlorous acid （HClO））.The results indicated that the effects of Cl- on the reaction mechanism were different under various activated conditions.For UV/PS and Thermal/PS,the inhibition tendency became more clear as the Cl- concentration increased,probably due to the reaction between Cl- and SO4-.and the generation of Cl2-.or HClO.For UV/PMS,Cl- did not exhibit inhibition when the concentration was below 0.1 mol/L.As Cl- concentration reached to 1.0 mol/L,the decolorization rate of AO7 was,however,accelerated,possibly because PMS directly reacts with Cl- to form HClO.For Co2＋ /PMS,Cl- exhibited a significant inhibiting effect even at low concentration （ 0.01 mol/L）.When Cl- concentration exceeded 0.1 mol/L,the activation of PMS by Co 2＋ was almost completely inhibited.Under this condition,HClO maybe played a major role in decolorization of AO7.The results implicated that chloride ion is an important factor in SO4-.-based degradation of organic contamination in chloride-containing water.展开更多
The microstructural evolution and oxidation resistance of multi-walled carbon nanotubes （MWCNTs） by di- rectly heating silicon powder and MWCNTs in a coke bed from 1000 to 1500 ~C are investigated with the aid of X-...The microstructural evolution and oxidation resistance of multi-walled carbon nanotubes （MWCNTs） by di- rectly heating silicon powder and MWCNTs in a coke bed from 1000 to 1500 ~C are investigated with the aid of X-ray diffraction （XRD）, scanning electron microscopy （SEM）, high resolution transmission electron microscopy （HRTEM） and thermogravimetry-differential scanning calorimetry （TG-DSC）. The results showed that the morphology and microstructure of MWCNTs did not change much after being treated from 1000 ~C to 1200 ~C. An obvious SiC coating was formed on the surface of MWCNTs from 1300 to 1400 ~C. Up to 1500 ~C, nearly all the MWCNTs transformed into SiC nanowires. The oxidation resistance of the treated MWCNTs was improved compared with as-received ones. Non-isothermal kinetics showed that the oxidation activation energy of the treated MWCNTs reached 208 kJ/mol, much higher than 264 k J/tool of as-received ones.展开更多
Hydroxyl radicals(·OH) generated on anode play a vital role in electrochemical oxidation(EO) of organic pollutants for water treatment. Inspired by the four-electron oxygen evolution reaction(OER), we supposed an...Hydroxyl radicals(·OH) generated on anode play a vital role in electrochemical oxidation(EO) of organic pollutants for water treatment. Inspired by the four-electron oxygen evolution reaction(OER), we supposed an anode-selection strategy to stabilize deeply oxidized states(*O and*OOH) which are beneficial to generating·OH. To verify the hypothesis, a candidate anode component(MIL-101(Cr), a well-known metal-organic framework with active variable-valence transition metal centers) was used to coat Ti/TiO_(2)plate to fabricate anodes. Compared to TiO_(2)(101) plane on undecorated anode surface, fast and complete removal of aniline and phenol, and improved energy utilization were achieved on MIL-101(Cr)-coatedTi/TiO_(2)anode. Mechanism investigation, including pollutant degradation pathways, showed the predominate contribution(69.60%–75.13%) of·OH in pollutant mineralization. Density functional theory(DFT)computations indicated Cr site in MIL-101(Cr) was more conducive to stabilizing*O and*OOH, leading to thermodynamical spontaneous generation of·OH. This work opens up an exciting avenue to explore·OH production, and supplies a useful guidance to the development of anode materials for EO process.展开更多
There are two theories regarding the origin of the remarkable synergistic effect observed in Au‐Ag bimetallic catalysts when applied to various oxidative reactions. One is based on the importance of the contact inter...There are two theories regarding the origin of the remarkable synergistic effect observed in Au‐Ag bimetallic catalysts when applied to various oxidative reactions. One is based on the importance of the contact interfaces between AgOx regions and the surface of the bulk Au as active working sites, while the other holds that charge transfer from Ag to Au in a surface Au‐Ag alloy causes the catalytic activity. One key point in examining these theories and determining the origin of the synergy in‐volves determining whether or not Ag exists as an oxide or as a metallic alloy on the Au surface. To confirm that enhanced activity results from contact between Ag2O and Au nanoparticles （NPs）, a comparative study of catalytic CO oxidation over Au/Ag2O and Ag2O was performed in the present work, using a closed recirculation reaction system. A reaction mixture consisting of a stoichiometric composition of CO and O2 （CO/O2=2/1） was supplied to both catalysts and the resulting pressure decrease rates were tracked, from which the amounts of gas consumed as well as the quantity of CO2 produced were determined. The steady state reactions of both Au/Ag2O and Ag2O did not lead to any meaningful difference in the rate of pressure decrease during the oxidation. The pressure decrease over both catalysts was attributed to the reduction of surface lattice O on Ag2O by CO. The results obtained for Au/Ag2O are in good agreement with previous data resulting from the use of Ag‐contaminated Au powder （Ag/Au‐b） having an oxidized surfaces. This finding suggests that the perimeters between AgOx zones and the bulk Au surface may not function as active sites during CO oxidation. A review of previous results obtained with Ag/Au‐b specimens having so‐called steady state surfaces indicates that AgOx species in such materials are reduced to the 0 state to form a Ag‐Au alloy that provides the active sites.展开更多
The oxidation of lignite and bituminous coal samples modified by 5 wt%(in terms of dry salt)addition of copper salts Cu(NO_(3))_(2),CuSO_(4),and Cu(CH_(3)COO)_(2) was studied.The samples’reactivity was studied by the...The oxidation of lignite and bituminous coal samples modified by 5 wt%(in terms of dry salt)addition of copper salts Cu(NO_(3))_(2),CuSO_(4),and Cu(CH_(3)COO)_(2) was studied.The samples’reactivity was studied by thermogravimetry within a temperature range of 45–600℃ at a heating rate of 2.5℃/min in an oxidizing environment.The introduction of activating additives has resulted in a significant decrease in the temperature of intense oxidation onset(ΔT_(i)=20/94℃),in a reduction in the sample residence time in the volatile matter release region(Δt_(e)=2/22 min)and the total duration of the coal combustible mass oxidation(Δt_(f)=8/14 min).The Friedman method was used to calculate the activation energy values for the oxidation process of the modified samples.The maximum change in activation energy values was observed for the bituminous coal sample.The possible mechanism behind the action of the copper-salt additives,which activate the oxidation of lignite and bituminous coal,is discussed.According to the data of mass spectrometric analysis,the concentration of NOx in the reaction products decreases as the temperature of the activated oxidation process is shifted towards the low-temperature region.展开更多
The catalytic activity of Perovskite-type mixed oxides (LaCoO3, PrCoO3 and SmCoO3) for the reduction of cyclohexanone to cyclohexanol with 2-propanol (Meerwein-PonndorfVerley reduction) has been studied. The data have...The catalytic activity of Perovskite-type mixed oxides (LaCoO3, PrCoO3 and SmCoO3) for the reduction of cyclohexanone to cyclohexanol with 2-propanol (Meerwein-PonndorfVerley reduction) has been studied. The data have been correlated with the surface electron donor properties of these mixed oxides展开更多
In this study,a series of Co_3O_4/ mildly oxidized graphite oxide(mGO) nanocatalysts(Co_3O_4/ mGO-l,Co_3O_4/ mGO-2 and Co_3O_4/mGO-3) were synthesized through solvothermal method and used as a mediator for the heterog...In this study,a series of Co_3O_4/ mildly oxidized graphite oxide(mGO) nanocatalysts(Co_3O_4/ mGO-l,Co_3O_4/ mGO-2 and Co_3O_4/mGO-3) were synthesized through solvothermal method and used as a mediator for the heterogeneous peroxymonosulfate(PMS)activation.The performance of CO_3O_4 / mGO/PMS system was investigated using acid orange 7(AO7).Results showed that Co_3O_4/mGO-3 had the best degradation efficiency of AO7 and the removal rate was above 90%in about 6 min.The phenomenon indicated the catalytic activity of Co_3O_4/mGO composites was related to the oxidation degree of graphite oxide(GO).In addition,experiments showed the content of Co_3O_4 had an effect on the catalytic activity.The composites were characterized with X-ray powder diffraction(XRD),FTIR,Raman,X-ray photoelectron spectroscopy(XPS) and transmission electron microscopy(TEM).According to the charactrization and synergistic catalytic mechanism,the generation of Co—OH complexes found to be the initial step to activate PMS in the heterogeneous system of Co_3O_4/mGO hybrid.展开更多
Polycrystalline SnO2 fine powder consisting of nano-particles （SnO2-NP）, SnO2 nano-sheets （SnO2-NS）, and SnO2 containing both nano-rods and nano-particles （SnO2-NR＋NP） were prepared and used for CO oxidation. S...Polycrystalline SnO2 fine powder consisting of nano-particles （SnO2-NP）, SnO2 nano-sheets （SnO2-NS）, and SnO2 containing both nano-rods and nano-particles （SnO2-NR＋NP） were prepared and used for CO oxidation. SnO2-NS possesses a mesoporous structure and has a higher surface area, larger pore volume, and more active species than SnO2-NP, and shows improved activity. In contrast, although SnO2-NR＋NP has only a slightly higher surface area and pore volume, and slightly more active surface oxygen species than SnO2-NP, it has more exposed active （110） facets, which is the reason for its improved oxidation activity. Water vapor has only a reversible and weak influence on SnO2-NS, therefore it is a potential catalyst for emission control processes.展开更多
The oxidation kinetics and composition of oxide scales on low carbon steel （SPHC） were studied during i- sothermal oxidation. Thermogravimetric analyzer （TGA） was used to simulate isothermal oxidation process of S...The oxidation kinetics and composition of oxide scales on low carbon steel （SPHC） were studied during i- sothermal oxidation. Thermogravimetric analyzer （TGA） was used to simulate isothermal oxidation process of SPHC for 240 min under air condition, and the temperature range was from 500 to 900 ℃. Scanning electron microscope （SEM） was used to observe cross-sectional scale morphology and analyze composition distribution of oxide scales. The morphology of oxide scale was classical three-layer structure. Fe2 03 developed as whiskers at the outermost lay- er, and interlayer was perforated-plate Fe3 04 while innermost layer was pyramidal FeO. From the oxidation curves, the oxidation mass gain per unit area with time was of parabolic relation and oxidation rate slowed down. On the ba- sis of experimental data, the isothermal oxidation kinetics model was derived and oxidation activation energy of SPHC steel was 127. 416 kJ/mol calculated from kinetics data.展开更多
Bioleaching of sulfide minerals by bacteria, mainly Thiobacillus ferrooxidans(T.f.) and Thiobacillus thiooxidans, plays an important role in hydrometallurgy because of its economic and environmental attractions. The s...Bioleaching of sulfide minerals by bacteria, mainly Thiobacillus ferrooxidans(T.f.) and Thiobacillus thiooxidans, plays an important role in hydrometallurgy because of its economic and environmental attractions. The surveys of production process and the bacterial oxidation activity in the heap bioleaching were investigated. The results show that pH value is high, bacteria biomass and ferric concentration are low, generation time (above 7.13 h) is long in leachate, and less bacteria are adsorbed on the ores. The bacteria in the leachate exposing on the surface and connecting with mineral, have much faster oxidation rate of Fe(Ⅱ) and shorter generation time, compared with those which are in the reservoir for a long time. There is diversity for oxidation activity of Fe(Ⅱ), while there is no diversity for oxidation of sulfur. So it is advisable to add sulfuric acid to degrade pH value to 2.0, add nutrients and shorten recycling time of leachate, so as to enhance bacteria concentration of leachate and the leaching efficiency.展开更多
For the first time,Au nanoparticles on graphene oxide（GO-AuNPs） were successfully fabricated without applying any additional reductants,just by the redox reaction between AuCl_4^（-1） and GO.Their structure was cha...For the first time,Au nanoparticles on graphene oxide（GO-AuNPs） were successfully fabricated without applying any additional reductants,just by the redox reaction between AuCl_4^（-1） and GO.Their structure was characterized by transmission electron microscopy and X-ray powder diffraction.The results show that flower-like AuNPs were successfully dispersed on GO surface.Importantly,they showed a high catalytic activity for the Suzuki-Miyaura coupling reaction in an aqueous medium.展开更多
For further understanding of self-heating of coal, we tested the reactions of seven different ranks of coal under inert atmosphere. In the test, 50-gram of coal sample ranged from 0.18 mm to 0.38 mm was put into a spe...For further understanding of self-heating of coal, we tested the reactions of seven different ranks of coal under inert atmosphere. In the test, 50-gram of coal sample ranged from 0.18 mm to 0.38 mm was put into a special designed copper reaction vessel and let pure nitrogen to flow into the coal sample from the bottom at a rate of 100 mL/min. The programmed temperature enclosure was run at a programmed rate of 0.8 ~C/min. The concentration of the carbon oxides and the coal temperature were tested. The results show that the coal reactions under inert atmosphere can generate CO and C02. The reactions under inert atmosphere are affected by coal ranks, initial pore structure of coal and sulfur content. For low ranks of coal, the productions of carbon oxides are piecewise. The coal temperature is lower than the surrounding temperature throughout the reactions under inert atmosphere, but it rises quickly and reaches a crossing point temperature in the later stage under dry-air atmosphere. Based on the analysis, it indicates the self-reaction of initial active groups exists in the self-heating of coal besides the reactions in the two parallel reactions model. Spontaneous combustion of coal is due to both the oxidation heat accumulation and the chain reaction. A new reaction model of self-heating of coal was orooosed.展开更多
Nanowire-shaped α-Mo O3 was synthesized on a large scale by hydrothermal route.Nanocrystalline α-Mo2 C phase was obtained by the carburization of α-Mo O3 nanowires with urea as a carbon source precursor.The phase p...Nanowire-shaped α-Mo O3 was synthesized on a large scale by hydrothermal route.Nanocrystalline α-Mo2 C phase was obtained by the carburization of α-Mo O3 nanowires with urea as a carbon source precursor.The phase purity and crystalline size of the synthesized materials were ascertained by using powder X-ray diffraction.The shape and morphology of synthesized materials were characterized by field-emission scanning electron microscopy（FE-SEM） and high resolution transmission electron microscopy（HR-TEM）.The electrocatalytic activity of α-Mo2 C for I-/I3^-redox couple was investigated by the cyclic voltammetry.The synthesized α-Mo2 C was subsequently applied as counter electrode in dye-sensitized solar cells to replace the expensive platinum.展开更多
Pd@Zr/Ce O2 core-shell catalyst prepared by hydrothermal method was applied in CO oxidation reaction, exhibiting high CO oxidation activity at low temperature.XRD（X-ray diffraction） analysis demonstrated that the re...Pd@Zr/Ce O2 core-shell catalyst prepared by hydrothermal method was applied in CO oxidation reaction, exhibiting high CO oxidation activity at low temperature.XRD（X-ray diffraction） analysis demonstrated that the remarkable enhancement of catalytic performance was found to depend on the presence of more oxygen vacancies in the core-shell structure, which contributed higher content of and ready release of active oxygen species at low temperature, confirmed by H2-TPR（temperature programed reduction） results.Interestingly, introducing a small amount of zirconium（0.5 wt.%） exhibited a significant improvement of catalytic activity because the introduction of Zr further improved the amount of crystal defects and promoted the migration of oxygen species.展开更多
Ozonation of oxalate in aqueous phase was performed with a commercial activated carbon（AC）in this work. The effect of AC dosage and solution pH on the contribution of hydroxyl radicals（HOU） in bulk solution and ox...Ozonation of oxalate in aqueous phase was performed with a commercial activated carbon（AC）in this work. The effect of AC dosage and solution pH on the contribution of hydroxyl radicals（HOU） in bulk solution and oxidation on the AC surface to the removal of oxalate was studied. We found that the removal of oxalate was reduced by tert-butyl alcohol（tBA） with low dosages of AC,while it was hardly affected by tBA when the AC dosage was greater than 0.3 g/L. tBA also inhibited ozone decomposition when the AC dosage was no more than 0.05 g/L, but it did not work when the AC dosage was no less than 0.1 g/L. These observations indicate that HOUin bulk solution and oxidation on the AC surface both contribute to the removal of oxalate. HOU oxidation in bulk solution is significant when the dosage of AC is low, whereas surface oxidation is dominant when the dosage of AC is high. The oxalate removal decreased with increasing pH of the solution with an AC dosage of 0.5 g/L. The degradation of oxalate occurs mainly through surface oxidation in acid and neutral solution, but through HOUoxidation in basic bulk solution. A mechanism involving both HOUoxidation in bulk solution and surface oxidation was proposed for AC enhanced ozonation of oxalate.展开更多
To confirm sub-regular solution model valid for predicting the activity of component in binary oxide systems, seven systems in the whole concentration and twelve systems presenting saturation concentration have been s...To confirm sub-regular solution model valid for predicting the activity of component in binary oxide systems, seven systems in the whole concentration and twelve systems presenting saturation concentration have been studied. The total average relative errors of component 1 and 2 are 3.2 % and 4.1% respectively by application of the sub-regular solution model into the systems within the whole concentration. However, the total average relative errors are 16 % and 1088 % in the systems presenting saturation concentration. The results show that sub-regular solu- tion model is not good for predicting the systems presenting saturation concentration, especially for the systems con- taining acidic or neutral oxide. The reason may be that the influence of the two types of oxide on the configuration is greater in binary oxide systems. These oxides can be present in the form of complex anion partly, Si-O, Al-O, Ti-O and so on, for example （SiO4）4-. That is contrary to sub-regular solution model which is supposed that the oxide systems consist of cation and O2-. But compared with regular solution model and quasi-regular solution model, sub- regular solution model is closer to the characteristics of actual solution and the calculated results are superior.展开更多
The process of preparing anodic oxide film containing active sites and electroless nickel plating on highly active rare earth magnesium alloy was developed.The formation mechanism of electroless nickel plating on acti...The process of preparing anodic oxide film containing active sites and electroless nickel plating on highly active rare earth magnesium alloy was developed.The formation mechanism of electroless nickel plating on active anodic oxide film and the structure and properties of the composite coating were studied by several surface and electrochemical techniques.The results showed that Ag nanograins with an average size of 10 nm were embedded into the anodic oxide film with pores of 0.1−2μm.Ag nanoparticles provided a catalytic site for the deposition of Ni-B alloy,and the Ni crystal nucleus was first grown in horizontal mode and then in cylindrical mode.The corrosion potential of the composite coating increased by 1.37 V and the corrosion current reduced two orders of magnitude due to the subsequent deposition of Ni-P alloy.The high corrosion resistance was attributed to the misaligning of these micro defects in the three different layers and the amorphous structure of the Ni-P alloy in the outer layer.These findings provide a new idea for electroless nickel plating on anodic oxide film.展开更多
It remains unclear whether dicofol should be defined as a persistent organic pollutant. Its environmental persistence has gained attention. This study focused on its degradation by cellulase. Cellulase was separated u...It remains unclear whether dicofol should be defined as a persistent organic pollutant. Its environmental persistence has gained attention. This study focused on its degradation by cellulase. Cellulase was separated using a gel chromatogram, and its degradation activity towards dicofol involved its endoglucanase activity. By analyzing the kinetic parameters of cellulase reacting with mixed substrates, it was shown that cellulase reacted on dicofol and carboxyl methyl cellulose through two different active centers. Thus, the degradation of dicofol was shown to be an oxidative process by cellulase. Next, by comparing the impacts of tert-butyl alcohol（a typical OH free-radical inhibitor） on the removal efficiencies of dicofol under both cellulase and Fenton reagent systems, it was shown that the removal of dicofol was initiated by OH free radicals produced by cellulase. Finally, 4,4′-dichlorodibenzophenone and chloride were detected using gas chromatography mass spectrometry and ion chromatography analysis, which supported our hypothesis. The reaction mechanism was analyzed and involved an attack by OH free radicals at the orthocarbon of dicofol, resulting in the degradation product 4,4′-dichloro-dibenzophenone.展开更多
6-Substituted 5,8-O-dimethyl-1,4-naphthoquinones（6-DMNQ）,the promising anticancer scaffolds,were selectively generated by oxidative demethylation of 2-substituted 1,4,5,8-tetramethoxynaphthalenes with CAN in EtOAc/H...6-Substituted 5,8-O-dimethyl-1,4-naphthoquinones（6-DMNQ）,the promising anticancer scaffolds,were selectively generated by oxidative demethylation of 2-substituted 1,4,5,8-tetramethoxynaphthalenes with CAN in EtOAc/H2O in comparatively high yields.An interesting finding was that apart from the reported electron-withdrawing effects of substituents on position 2 of naphthalene ring,regioselective synthesis of 6-DMNQ was largely dependent on the steric effects in CAN-mediated oxidation.The selective cytotoxicities of 6-DMNQ from the in vitro cell-based assays were exhibited between the cancer cells and normal cells.Moreover,most of sulfur-containing 6-DMNQ derivatives displayed better anticancer activities than the corresponding oxygen-containing ones,which could provide an available strategy for the design of 6-DMNQ derivatives as potential anticancer agents.展开更多
基金Project(50974140) supported by the National Natural Science Foundation of ChinaProject(20090162110054) supported by Specialized Research Fund for the Doctoral Program of Higher Education of China
文摘The apparent sulfur oxidation activities of four pure thermophilic archaea, Acidianus brierleyi （JCM 8954）, Metallosphaera sedula （YN 23）, Acidianus manzaensis （YN 25） and Sulfolobus metallicus （YN 24） and their mixture in bioleaching chalcopyrite were compared, which were characterized indirectly by the evolution of the cells concentration, pH value and sulfate ions concentration in solution. The results show that the mixed culture contributed significantly to the raising of leaching rate, which suggests that the mixed culture had a higher sulfur oxidation activity than the pure culture. Meanwhile, the results also indicate that the changes of parameters characterizing the sulfur oxidation activity of thermophilic archaea are often influenced by many factors, so it is hard to reflect accurately the specific sulfur oxidation activities among the different sulfur-oxidizing microbes when bioleaching chalcopyrite at different conditions. Accordingly, an efficient method to characterize microbial sulfur oxidation activity appears to be desirable.
基金supported by the National Natural Science Foundation of China (No. 21107101)the Fundamental Research Funds for the Central Universities of China (Ocean University of China)(No.201113005)
文摘The effects of chloride anion （Cl-） （up to 1.0 mol/L） on the decolorization of a model compound,azo dye Acid Orange 7 （AO7）,by sulfate radical （SO4-） based-peroxydisulfate （PS） or peroxymonosulfate （PMS） oxidation under various activated conditions （UV 254 nm /PS,Thermal （70°C/PS,UV 254 nm /PMS,Co 2＋ /PMS） were investigated.Methanol and NH4 ＋ were used as quenching reagents to determine the contributions of active chlorine species （dichloride radical （Cl2-.） and hypochlorous acid （HClO））.The results indicated that the effects of Cl- on the reaction mechanism were different under various activated conditions.For UV/PS and Thermal/PS,the inhibition tendency became more clear as the Cl- concentration increased,probably due to the reaction between Cl- and SO4-.and the generation of Cl2-.or HClO.For UV/PMS,Cl- did not exhibit inhibition when the concentration was below 0.1 mol/L.As Cl- concentration reached to 1.0 mol/L,the decolorization rate of AO7 was,however,accelerated,possibly because PMS directly reacts with Cl- to form HClO.For Co2＋ /PMS,Cl- exhibited a significant inhibiting effect even at low concentration （ 0.01 mol/L）.When Cl- concentration exceeded 0.1 mol/L,the activation of PMS by Co 2＋ was almost completely inhibited.Under this condition,HClO maybe played a major role in decolorization of AO7.The results implicated that chloride ion is an important factor in SO4-.-based degradation of organic contamination in chloride-containing water.
基金supported by the Natural Science Foundation of Hubei Province (No.2009CDA050)the New Century Excellent Talents in University (No. NCET-10-0137)the National Natural Science Foundation of China (No. 51072143)
文摘The microstructural evolution and oxidation resistance of multi-walled carbon nanotubes （MWCNTs） by di- rectly heating silicon powder and MWCNTs in a coke bed from 1000 to 1500 ~C are investigated with the aid of X-ray diffraction （XRD）, scanning electron microscopy （SEM）, high resolution transmission electron microscopy （HRTEM） and thermogravimetry-differential scanning calorimetry （TG-DSC）. The results showed that the morphology and microstructure of MWCNTs did not change much after being treated from 1000 ~C to 1200 ~C. An obvious SiC coating was formed on the surface of MWCNTs from 1300 to 1400 ~C. Up to 1500 ~C, nearly all the MWCNTs transformed into SiC nanowires. The oxidation resistance of the treated MWCNTs was improved compared with as-received ones. Non-isothermal kinetics showed that the oxidation activation energy of the treated MWCNTs reached 208 kJ/mol, much higher than 264 k J/tool of as-received ones.
基金supported by the National Natrual Science of China (NSFC, Nos. 51978341, 52070100 and 52011530433)the Natural Science Foundation of Jiangsu Province of China (No. BK20190087)Jiangsu Key Laboratory of New Power Batteries, and a project funded by the Priority Academic Program Development (PAPD) of Jiangsu Higher Education Institutions。
文摘Hydroxyl radicals(·OH) generated on anode play a vital role in electrochemical oxidation(EO) of organic pollutants for water treatment. Inspired by the four-electron oxygen evolution reaction(OER), we supposed an anode-selection strategy to stabilize deeply oxidized states(*O and*OOH) which are beneficial to generating·OH. To verify the hypothesis, a candidate anode component(MIL-101(Cr), a well-known metal-organic framework with active variable-valence transition metal centers) was used to coat Ti/TiO_(2)plate to fabricate anodes. Compared to TiO_(2)(101) plane on undecorated anode surface, fast and complete removal of aniline and phenol, and improved energy utilization were achieved on MIL-101(Cr)-coatedTi/TiO_(2)anode. Mechanism investigation, including pollutant degradation pathways, showed the predominate contribution(69.60%–75.13%) of·OH in pollutant mineralization. Density functional theory(DFT)computations indicated Cr site in MIL-101(Cr) was more conducive to stabilizing*O and*OOH, leading to thermodynamical spontaneous generation of·OH. This work opens up an exciting avenue to explore·OH production, and supplies a useful guidance to the development of anode materials for EO process.
基金supported by CREST project(Catalyst Design of Gold Clusters through Junction Effect with Metal oxides,Carbons,and Polymers)sponsored by Japan Science and Technology Agency(JST)~~
文摘There are two theories regarding the origin of the remarkable synergistic effect observed in Au‐Ag bimetallic catalysts when applied to various oxidative reactions. One is based on the importance of the contact interfaces between AgOx regions and the surface of the bulk Au as active working sites, while the other holds that charge transfer from Ag to Au in a surface Au‐Ag alloy causes the catalytic activity. One key point in examining these theories and determining the origin of the synergy in‐volves determining whether or not Ag exists as an oxide or as a metallic alloy on the Au surface. To confirm that enhanced activity results from contact between Ag2O and Au nanoparticles （NPs）, a comparative study of catalytic CO oxidation over Au/Ag2O and Ag2O was performed in the present work, using a closed recirculation reaction system. A reaction mixture consisting of a stoichiometric composition of CO and O2 （CO/O2=2/1） was supplied to both catalysts and the resulting pressure decrease rates were tracked, from which the amounts of gas consumed as well as the quantity of CO2 produced were determined. The steady state reactions of both Au/Ag2O and Ag2O did not lead to any meaningful difference in the rate of pressure decrease during the oxidation. The pressure decrease over both catalysts was attributed to the reduction of surface lattice O on Ag2O by CO. The results obtained for Au/Ag2O are in good agreement with previous data resulting from the use of Ag‐contaminated Au powder （Ag/Au‐b） having an oxidized surfaces. This finding suggests that the perimeters between AgOx zones and the bulk Au surface may not function as active sites during CO oxidation. A review of previous results obtained with Ag/Au‐b specimens having so‐called steady state surfaces indicates that AgOx species in such materials are reduced to the 0 state to form a Ag‐Au alloy that provides the active sites.
基金This work was supported by the Ministry of Science and Higher Education of the Russian Federation(projects No.FSWW-2020-0022 and AAAA-A17-117041710086-6).
文摘The oxidation of lignite and bituminous coal samples modified by 5 wt%(in terms of dry salt)addition of copper salts Cu(NO_(3))_(2),CuSO_(4),and Cu(CH_(3)COO)_(2) was studied.The samples’reactivity was studied by thermogravimetry within a temperature range of 45–600℃ at a heating rate of 2.5℃/min in an oxidizing environment.The introduction of activating additives has resulted in a significant decrease in the temperature of intense oxidation onset(ΔT_(i)=20/94℃),in a reduction in the sample residence time in the volatile matter release region(Δt_(e)=2/22 min)and the total duration of the coal combustible mass oxidation(Δt_(f)=8/14 min).The Friedman method was used to calculate the activation energy values for the oxidation process of the modified samples.The maximum change in activation energy values was observed for the bituminous coal sample.The possible mechanism behind the action of the copper-salt additives,which activate the oxidation of lignite and bituminous coal,is discussed.According to the data of mass spectrometric analysis,the concentration of NOx in the reaction products decreases as the temperature of the activated oxidation process is shifted towards the low-temperature region.
文摘The catalytic activity of Perovskite-type mixed oxides (LaCoO3, PrCoO3 and SmCoO3) for the reduction of cyclohexanone to cyclohexanol with 2-propanol (Meerwein-PonndorfVerley reduction) has been studied. The data have been correlated with the surface electron donor properties of these mixed oxides
基金Innovation Program of Shanghai Municipal Education Commission,China(No.12ZZ069)Research Fund for the Doctoral Program of Higher Education,China(No.20130075110006)
文摘In this study,a series of Co_3O_4/ mildly oxidized graphite oxide(mGO) nanocatalysts(Co_3O_4/ mGO-l,Co_3O_4/ mGO-2 and Co_3O_4/mGO-3) were synthesized through solvothermal method and used as a mediator for the heterogeneous peroxymonosulfate(PMS)activation.The performance of CO_3O_4 / mGO/PMS system was investigated using acid orange 7(AO7).Results showed that Co_3O_4/mGO-3 had the best degradation efficiency of AO7 and the removal rate was above 90%in about 6 min.The phenomenon indicated the catalytic activity of Co_3O_4/mGO composites was related to the oxidation degree of graphite oxide(GO).In addition,experiments showed the content of Co_3O_4 had an effect on the catalytic activity.The composites were characterized with X-ray powder diffraction(XRD),FTIR,Raman,X-ray photoelectron spectroscopy(XPS) and transmission electron microscopy(TEM).According to the charactrization and synergistic catalytic mechanism,the generation of Co—OH complexes found to be the initial step to activate PMS in the heterogeneous system of Co_3O_4/mGO hybrid.
基金supported by the National Natural Science Foundation of China (21263015)the Education Department of Jiangxi Province (KJLD14005)the Natural Science Foundation of Jiangxi Province(20151BBE50006,20122BAB203009)~~
文摘Polycrystalline SnO2 fine powder consisting of nano-particles （SnO2-NP）, SnO2 nano-sheets （SnO2-NS）, and SnO2 containing both nano-rods and nano-particles （SnO2-NR＋NP） were prepared and used for CO oxidation. SnO2-NS possesses a mesoporous structure and has a higher surface area, larger pore volume, and more active species than SnO2-NP, and shows improved activity. In contrast, although SnO2-NR＋NP has only a slightly higher surface area and pore volume, and slightly more active surface oxygen species than SnO2-NP, it has more exposed active （110） facets, which is the reason for its improved oxidation activity. Water vapor has only a reversible and weak influence on SnO2-NS, therefore it is a potential catalyst for emission control processes.
基金Sponsored by National Natural Science Foundation of China(51204047)National Key Technology Research and Development Program in 12th Five-year Plan of China(2011BAE13B04)The Fundamental Research Funds for the Central Universities of China(N100307006)
文摘The oxidation kinetics and composition of oxide scales on low carbon steel （SPHC） were studied during i- sothermal oxidation. Thermogravimetric analyzer （TGA） was used to simulate isothermal oxidation process of SPHC for 240 min under air condition, and the temperature range was from 500 to 900 ℃. Scanning electron microscope （SEM） was used to observe cross-sectional scale morphology and analyze composition distribution of oxide scales. The morphology of oxide scale was classical three-layer structure. Fe2 03 developed as whiskers at the outermost lay- er, and interlayer was perforated-plate Fe3 04 while innermost layer was pyramidal FeO. From the oxidation curves, the oxidation mass gain per unit area with time was of parabolic relation and oxidation rate slowed down. On the ba- sis of experimental data, the isothermal oxidation kinetics model was derived and oxidation activation energy of SPHC steel was 127. 416 kJ/mol calculated from kinetics data.
文摘Bioleaching of sulfide minerals by bacteria, mainly Thiobacillus ferrooxidans(T.f.) and Thiobacillus thiooxidans, plays an important role in hydrometallurgy because of its economic and environmental attractions. The surveys of production process and the bacterial oxidation activity in the heap bioleaching were investigated. The results show that pH value is high, bacteria biomass and ferric concentration are low, generation time (above 7.13 h) is long in leachate, and less bacteria are adsorbed on the ores. The bacteria in the leachate exposing on the surface and connecting with mineral, have much faster oxidation rate of Fe(Ⅱ) and shorter generation time, compared with those which are in the reservoir for a long time. There is diversity for oxidation activity of Fe(Ⅱ), while there is no diversity for oxidation of sulfur. So it is advisable to add sulfuric acid to degrade pH value to 2.0, add nutrients and shorten recycling time of leachate, so as to enhance bacteria concentration of leachate and the leaching efficiency.
基金supported by the National Science Foundation of China(No.21074089)Tianjin Municipal Science and Technology Commission,China(No.09JCZDJC23300)
文摘For the first time,Au nanoparticles on graphene oxide（GO-AuNPs） were successfully fabricated without applying any additional reductants,just by the redox reaction between AuCl_4^（-1） and GO.Their structure was characterized by transmission electron microscopy and X-ray powder diffraction.The results show that flower-like AuNPs were successfully dispersed on GO surface.Importantly,they showed a high catalytic activity for the Suzuki-Miyaura coupling reaction in an aqueous medium.
基金Financial supports for this research provided by the National Natural Science Foundation of China (No. 50927403)the Fundamental Research Funds for the Central Universities (No.2011RC06)the Jiangsu Natural Science Foundation (No.BK2009004)
文摘For further understanding of self-heating of coal, we tested the reactions of seven different ranks of coal under inert atmosphere. In the test, 50-gram of coal sample ranged from 0.18 mm to 0.38 mm was put into a special designed copper reaction vessel and let pure nitrogen to flow into the coal sample from the bottom at a rate of 100 mL/min. The programmed temperature enclosure was run at a programmed rate of 0.8 ~C/min. The concentration of the carbon oxides and the coal temperature were tested. The results show that the coal reactions under inert atmosphere can generate CO and C02. The reactions under inert atmosphere are affected by coal ranks, initial pore structure of coal and sulfur content. For low ranks of coal, the productions of carbon oxides are piecewise. The coal temperature is lower than the surrounding temperature throughout the reactions under inert atmosphere, but it rises quickly and reaches a crossing point temperature in the later stage under dry-air atmosphere. Based on the analysis, it indicates the self-reaction of initial active groups exists in the self-heating of coal besides the reactions in the two parallel reactions model. Spontaneous combustion of coal is due to both the oxidation heat accumulation and the chain reaction. A new reaction model of self-heating of coal was orooosed.
基金the financial support from the Department of Atomic Energy–Board of Research in Nuclear Sciences(DAE-BRNS)(Grant No.2013/37P/1/BRNS),Mumbai,India
文摘Nanowire-shaped α-Mo O3 was synthesized on a large scale by hydrothermal route.Nanocrystalline α-Mo2 C phase was obtained by the carburization of α-Mo O3 nanowires with urea as a carbon source precursor.The phase purity and crystalline size of the synthesized materials were ascertained by using powder X-ray diffraction.The shape and morphology of synthesized materials were characterized by field-emission scanning electron microscopy（FE-SEM） and high resolution transmission electron microscopy（HR-TEM）.The electrocatalytic activity of α-Mo2 C for I-/I3^-redox couple was investigated by the cyclic voltammetry.The synthesized α-Mo2 C was subsequently applied as counter electrode in dye-sensitized solar cells to replace the expensive platinum.
基金Project supported by the Introduction of Talent and Technology Cooperation Plan of Tianjin
文摘Pd@Zr/Ce O2 core-shell catalyst prepared by hydrothermal method was applied in CO oxidation reaction, exhibiting high CO oxidation activity at low temperature.XRD（X-ray diffraction） analysis demonstrated that the remarkable enhancement of catalytic performance was found to depend on the presence of more oxygen vacancies in the core-shell structure, which contributed higher content of and ready release of active oxygen species at low temperature, confirmed by H2-TPR（temperature programed reduction） results.Interestingly, introducing a small amount of zirconium（0.5 wt.%） exhibited a significant improvement of catalytic activity because the introduction of Zr further improved the amount of crystal defects and promoted the migration of oxygen species.
基金supported by the National Natural Science Foundation of China (No. 21177130)the National Key Technology R&D Program (No. 2011BAC06B09)the Chinese Academy of Sciences Visiting Professorships for Senior International Scientists (No. 2009G2-28)
文摘Ozonation of oxalate in aqueous phase was performed with a commercial activated carbon（AC）in this work. The effect of AC dosage and solution pH on the contribution of hydroxyl radicals（HOU） in bulk solution and oxidation on the AC surface to the removal of oxalate was studied. We found that the removal of oxalate was reduced by tert-butyl alcohol（tBA） with low dosages of AC,while it was hardly affected by tBA when the AC dosage was greater than 0.3 g/L. tBA also inhibited ozone decomposition when the AC dosage was no more than 0.05 g/L, but it did not work when the AC dosage was no less than 0.1 g/L. These observations indicate that HOUin bulk solution and oxidation on the AC surface both contribute to the removal of oxalate. HOU oxidation in bulk solution is significant when the dosage of AC is low, whereas surface oxidation is dominant when the dosage of AC is high. The oxalate removal decreased with increasing pH of the solution with an AC dosage of 0.5 g/L. The degradation of oxalate occurs mainly through surface oxidation in acid and neutral solution, but through HOUoxidation in basic bulk solution. A mechanism involving both HOUoxidation in bulk solution and surface oxidation was proposed for AC enhanced ozonation of oxalate.
基金Item Sponsored by National Natural Science Foundation of China(50764006,50574045)Yunnan Basic Applied Research Foundation of China(2006E0021M)
文摘To confirm sub-regular solution model valid for predicting the activity of component in binary oxide systems, seven systems in the whole concentration and twelve systems presenting saturation concentration have been studied. The total average relative errors of component 1 and 2 are 3.2 % and 4.1% respectively by application of the sub-regular solution model into the systems within the whole concentration. However, the total average relative errors are 16 % and 1088 % in the systems presenting saturation concentration. The results show that sub-regular solu- tion model is not good for predicting the systems presenting saturation concentration, especially for the systems con- taining acidic or neutral oxide. The reason may be that the influence of the two types of oxide on the configuration is greater in binary oxide systems. These oxides can be present in the form of complex anion partly, Si-O, Al-O, Ti-O and so on, for example （SiO4）4-. That is contrary to sub-regular solution model which is supposed that the oxide systems consist of cation and O2-. But compared with regular solution model and quasi-regular solution model, sub- regular solution model is closer to the characteristics of actual solution and the calculated results are superior.
基金Project(5227010679)supported by the National Natural Science Foundation of China。
文摘The process of preparing anodic oxide film containing active sites and electroless nickel plating on highly active rare earth magnesium alloy was developed.The formation mechanism of electroless nickel plating on active anodic oxide film and the structure and properties of the composite coating were studied by several surface and electrochemical techniques.The results showed that Ag nanograins with an average size of 10 nm were embedded into the anodic oxide film with pores of 0.1−2μm.Ag nanoparticles provided a catalytic site for the deposition of Ni-B alloy,and the Ni crystal nucleus was first grown in horizontal mode and then in cylindrical mode.The corrosion potential of the composite coating increased by 1.37 V and the corrosion current reduced two orders of magnitude due to the subsequent deposition of Ni-P alloy.The high corrosion resistance was attributed to the misaligning of these micro defects in the three different layers and the amorphous structure of the Ni-P alloy in the outer layer.These findings provide a new idea for electroless nickel plating on anodic oxide film.
基金supported by the special fund provided by the State Key Joint Laboratory of Environmental Simulation and Pollution Control(Peking University,No.09Z02ESPCP)the Special Research Funding for Public Benefit Industries from National Ministry of Environmental Protection(No.201209020)
文摘It remains unclear whether dicofol should be defined as a persistent organic pollutant. Its environmental persistence has gained attention. This study focused on its degradation by cellulase. Cellulase was separated using a gel chromatogram, and its degradation activity towards dicofol involved its endoglucanase activity. By analyzing the kinetic parameters of cellulase reacting with mixed substrates, it was shown that cellulase reacted on dicofol and carboxyl methyl cellulose through two different active centers. Thus, the degradation of dicofol was shown to be an oxidative process by cellulase. Next, by comparing the impacts of tert-butyl alcohol（a typical OH free-radical inhibitor） on the removal efficiencies of dicofol under both cellulase and Fenton reagent systems, it was shown that the removal of dicofol was initiated by OH free radicals produced by cellulase. Finally, 4,4′-dichlorodibenzophenone and chloride were detected using gas chromatography mass spectrometry and ion chromatography analysis, which supported our hypothesis. The reaction mechanism was analyzed and involved an attack by OH free radicals at the orthocarbon of dicofol, resulting in the degradation product 4,4′-dichloro-dibenzophenone.
基金supported by National Natural Science Foundation of China(No.81373274)Ph.D.Programs Foundation of Ministry of Education China(No.20120073110068)Shanghai Biomedical Supporting Funding(No.15431900600)
文摘6-Substituted 5,8-O-dimethyl-1,4-naphthoquinones（6-DMNQ）,the promising anticancer scaffolds,were selectively generated by oxidative demethylation of 2-substituted 1,4,5,8-tetramethoxynaphthalenes with CAN in EtOAc/H2O in comparatively high yields.An interesting finding was that apart from the reported electron-withdrawing effects of substituents on position 2 of naphthalene ring,regioselective synthesis of 6-DMNQ was largely dependent on the steric effects in CAN-mediated oxidation.The selective cytotoxicities of 6-DMNQ from the in vitro cell-based assays were exhibited between the cancer cells and normal cells.Moreover,most of sulfur-containing 6-DMNQ derivatives displayed better anticancer activities than the corresponding oxygen-containing ones,which could provide an available strategy for the design of 6-DMNQ derivatives as potential anticancer agents.
