Electrospun nanofibrous separators,despite lacking superior mechanical strength,have gained widespread attention with high porosity and facile processing.Herein,utilizing the fact that thermal imidization temperature ...Electrospun nanofibrous separators,despite lacking superior mechanical strength,have gained widespread attention with high porosity and facile processing.Herein,utilizing the fact that thermal imidization temperature of poly(amic acid)(PAA)into polyimide(PI)coincides with the pre-oxidation temperature of polyacrylonitrile(PAN)into carbon fiber,we proposed a new cross-electrospinning strategy to obtain a composite nanofibrous separator(PI/oPAN)randomly interwoven by PI and pre-oxidized PAN(oPAN)nanofibers,via synchronously electrospinning the PAA and PAN onto the same collector and then heat-treating for 2 h at 300℃.The resultant PI/oPAN separator was able to preserve high porosity(71.7%),electrolyte wettability and thermal stability of PI nanofibrous membrane,and surprisingly exhibited high mechanical strength,being 3 times of PI,which mainly because of the numerous adhesion points generated by the melting of PAN in the pre-oxidation process.Meanwhile,the polar groups of oPAN and 3D fibrous network enhanced the PI/oPAN separator's ionic conductivity and Li+transference number,rendering the corresponding cell with more stable cycling performance than cells assembled with pure PI,PAN or commercial PP separator.Therefore,this work might provide a new avenue for the ongoing design and further development of LIB separators capable of high safety and high performance.展开更多
PAN fibers pre-oxidized at 240℃, 260℃, 280℃, 300℃ were treated in 8 T, 12 T, 16 T high magnetic fields, respectively. The experimental result implied that there were two kinds of magnetic units cyan and carbon-nit...PAN fibers pre-oxidized at 240℃, 260℃, 280℃, 300℃ were treated in 8 T, 12 T, 16 T high magnetic fields, respectively. The experimental result implied that there were two kinds of magnetic units cyan and carbon-nitrogen heterocycle in pre-oxidized PAN fibers, and the movement of magnetic units resulted in changes of orientation structure of pre-oxidized PAN fibers in high magnetic fields. Overall orientation increased with increase of magnetic field intensity and extension of processing time, whereas change of crystalline orientation depended on magnetic field intensity and content of carbon-nitrogen heterocycle due to the competition of two magnetic units. Furthermore, magnetic fields induced the conversion from amorphous region to crystal region and improved crystalline orooerties of ore-oxidized PAN fibers.展开更多
Three representative sulfide ore samples were collected from typical metal mines,and their corresponding pre-oxidized products were obtained under nature environment.The thermal behaviors of each sample at heating rat...Three representative sulfide ore samples were collected from typical metal mines,and their corresponding pre-oxidized products were obtained under nature environment.The thermal behaviors of each sample at heating rates of 5,10,15 and 20 °C/min in air flow from ambient temperature to 800 °C were studied by simultaneous thermal analysis and the TG/DSC curves before and after the pre-oxidation were compared.By the peak temperature of DTG curves,the whole reaction process for each sample was divided into different stages,and the apparent activation energies were calculated by the Ozawa-Flynn-Wall method.The results show that the reaction process of each sample after pre-oxidation is more complex,with quicker reaction rates,fewer heat production quantities,and higher or lower ignition-points.The apparent activation energies decrease from 364.017-474.228 kJ/mol to 244.523- 333.161 kJ/mol.Therefore,sulfide ores are more susceptible to spontaneous combustion after the pre-oxidation.展开更多
The effect of pre-oxidation degree of Panzhihua ilmenite concentrate on the gaseous reduction by carbon monoxide was investigated.The raw ilmenite concentrates were pre-oxidized at 600,700,800,900,and 1000°C for ...The effect of pre-oxidation degree of Panzhihua ilmenite concentrate on the gaseous reduction by carbon monoxide was investigated.The raw ilmenite concentrates were pre-oxidized at 600,700,800,900,and 1000°C for 2 h,respectively.The phase change,FeO content,and morphology after the oxidation at various temperatures were characterized.The oxidation degree was calculated according to the change of FeO content.Thermogravimetry was performed on the oxidized ilmenite concentrate samples(oxidized at 600,800,and 1000°C)at 850,900,and 950°C,respectively.The results show that the pre-oxidation of ilmenite concentrate can accelerate the reduction process:the higher pre-oxidation degree,the faster reduction rate.The high pre-oxidation degree of ilmenite concentrate is beneficial to accelerate the subsequent reduction process in two ways.Three stages of the reduction process were divided via the first derivatives of reduction degree,and the reduction mechanism and apparent activation energy were discussed subsequently.展开更多
The corrosion behavior of the pre-oxidized GH4169 alloy was studied after 20 h of exposure under a solid NaCl deposit film in a wet O_(2) environment at 600℃ by mass-gain measurements,X-ray diffraction,scanning elect...The corrosion behavior of the pre-oxidized GH4169 alloy was studied after 20 h of exposure under a solid NaCl deposit film in a wet O_(2) environment at 600℃ by mass-gain measurements,X-ray diffraction,scanning electron microscopy,transmission electron microscopy methods.The results indicate that the pre-oxidized GH4169 alloy undergoes serious corrosion in the corrosive condition.The preformed Cr_(2)O_(3) layer is gradually destroyed by deposit NaCl,and the inner Nb2O5 layer beneath the complete outer Cr_(2)O_(3) layer also reacts with NaCl to form NaNbO_(3).The electrochemical test results testified the existence of electrochemical reactions during this corrosion process.The corrosion behavior of pre-oxidized GH4169 under a solid NaCl deposit film in a wet O_(2) environment at 600℃has been discussed in detail.展开更多
Rationally regulating the porosity of hard carbon(HC),especially the closed pores matching the low potential plateau and the ultra-microporous structure suitable for Na+embedding,has been shown to be the key to improv...Rationally regulating the porosity of hard carbon(HC),especially the closed pores matching the low potential plateau and the ultra-microporous structure suitable for Na+embedding,has been shown to be the key to improving the sodium storage performance and initial coulombic efficiency(ICE).However,the preparation of such HC materials with specific pore structures still faces great challenges.Herein,a simple pre-oxidation strategy is employed to construct abundant closed ultra-microporous structures in soy protein powder-derived HC material,achieving a significant improvement in its ICE and platform capacity.The pre-oxidation process promotes the cross-linking degree of the soy protein,thereby hindering the directional growth of graphite domains during the carbonization process.The optimized HC exhibits ultra-high platform capacity(329 mAh g^(-1))and considerable energy density(148.5 Wh kg^(-1)).Based on the ex-situ Raman and X-ray photoelectron spectroscopy characterization results,the excellent sodium storage capacity of the HC material is attributed to the synergistic effect of adsorption-intercalation/filling.The presented work provides novel insights into the synthesis of other biomass-derived HC materials with abundant closed ultra-micro pores.展开更多
The influence of the certain specific vacuum pre-oxidation process on the phase transformation of thermally-grown oxides（TGO） was studied.The CoCrAlY high temperature corrosion resistance coatings were produced onto...The influence of the certain specific vacuum pre-oxidation process on the phase transformation of thermally-grown oxides（TGO） was studied.The CoCrAlY high temperature corrosion resistance coatings were produced onto the nickel-based superalloy substrate by high velocity oxygen fuel（HVOF）.It suggests that the TGO usually consists of a great number of chromium oxides,cobalt oxides and spinel oxides besides alumina during the initial period of the high temperature oxidation if the specimens are not subjected to the appropriate vacuum pre-oxidation process.Furthermore,the amount of alumina is strongly dependent on the partial pressure of oxygen;while the CoCr2O4 spinel oxides are usually formed under the conditions of higher partial pressure of oxygen during the initial period and the lower partial pressure of oxygen during the subsequent period of the isothermal oxidation.After the appropriate vacuum pre-oxidation process,the TGO is mainly composed of alumina that contains lower Y element,while alumina that contains higher Y element sporadically distributes,and the spinel oxides cannot be found.After a longer period of the isothermal oxidation,a small amount of porous CoCr2O4 and the chrome oxide sporadically distribute near the continuous alumina.Additionally,after the appropriate vacuum pre-oxidation process,the TGO growth rate is relatively slow.展开更多
An artificial neural network model was developed to predict the oxidation of refractory gold concentrate （RGC） by ozone and ferric ions. The concentration of ozone and ferric ions, pulp density, oxygen amount, leach...An artificial neural network model was developed to predict the oxidation of refractory gold concentrate （RGC） by ozone and ferric ions. The concentration of ozone and ferric ions, pulp density, oxygen amount, leaching time and temperature were employed as inputs to the network; the output of the network was the percentage of the ferric extraction iron from RGC. The multilayered feed-forward networks were trained by 33 sets of input-output patterns using a back propagation algorithm; a three-layer network with 8 neurons in the hidden layer gave optimal results. The model gave good predictions of high correlation coefficient （R2=0.966）. The predictions by ANN are more accurate when compared with conventional multivariate regression analysis （MVRA）. In addition, calculation with ANN model indicates that temperature is the predominant parameter and ozone concentration is the lesser influential parameter in the pre-oxidation process of refractory gold ore. The ANN neural network model accurately estimates the ferric extraction during pretreatment process of RGC in gold smelter plants and can be used to optimize the process parameters.展开更多
Due to its low cost and easy availability, the pitch is considered a promising precursor for soft carbon anodes. However, pitch-derived soft carbon shows a high graphitization degree and small interlayer spacing, resu...Due to its low cost and easy availability, the pitch is considered a promising precursor for soft carbon anodes. However, pitch-derived soft carbon shows a high graphitization degree and small interlayer spacing, resulting in its much lower sodium storage performance than hard carbon. We propose a novel preoxidation strategy to introduce additional oxygen atoms into the low-cost soft carbon precursor pitch to fabricate a defect-rich and large-interlayer spacing hard carbon anode(HPP-1100). Compared with the direct pyrolysis of pitch carbon, the sodium storage capacity of HPP-1100 is significantly improved from 120.3 m Ah/g to 306.7 m Ah/g, with an excellent rate and cycling capability(116.5 m Ah/g at 10 C). Moreover, when assorted with an O_(3)-Na(NiFeMn)1/3O_(2)cathode, the full cell delivers a high reversible capacity of 274.0 m Ah/g at 0.1 C with superb cycle life. This work provides a new solution for realizing the application of low-cost pitch anodes in Na-ion batteries.展开更多
Cyanobacterial bloom has many adverse effects on source water quality and drinking water production. The traditional water treatment process can hardly achieve satisfactory removal of algae cells. This review examines...Cyanobacterial bloom has many adverse effects on source water quality and drinking water production. The traditional water treatment process can hardly achieve satisfactory removal of algae cells. This review examines the impact of pre-oxidation on the removal of cyanobacteria by solid-liquid separation processes. It was reported that the introduction of chemical oxidants such as chlorine, potassium permanganate, and ozone in algae-laden water pretreatment could improve algae removal by the subsequent solid-liquid separation processes. However, over dosed oxidants can result in more serious water quality risks due to significant algae cell lysis and undesirable intracellular organic matter release. It was suggested that moderate pre-oxidation may enhance the removal of cyanobacteria without damaging algae cells. In this article, effects of moderate pretreatment on the solid-liquid separation processes(sedimentation, dissolved air flotation, and membrane filtration) are reviewed.展开更多
The direct sulfidization of cuprite is inefficient because cuprite is a copper-oxide mineral with a strong surface hydrophilicity.In this study,oxidant was used to modify cuprite surfaces to regulate the sulfidization...The direct sulfidization of cuprite is inefficient because cuprite is a copper-oxide mineral with a strong surface hydrophilicity.In this study,oxidant was used to modify cuprite surfaces to regulate the sulfidization of cuprite.Microflotation tests showed that the flotation recovery of pre-oxidized cuprite was nearly25% higher than that of direct sulfidization flotation,which indicates that the cuprite surface activity was enhanced after pre-oxidation by Cu(Ⅰ) species(weak affinity with sulfur ions) transformation to Cu(Ⅱ)species(strong affinity with sulfur ions).Zeta potential,scanning electron microscopy-energy dispersive X-ray spectroscopy,X-ray photoelectron spectroscopy,and time-of-flight secondary ion mass spectrometry results showed that pre-oxidation improved cuprite sulfidization and promoted the formation of copper-sulfide species on the cuprite surfaces.The mineral surface stability and thus,xanthate species adsorption on the cuprite surfaces were improved.The surface-adsorption measurements and infrared spectroscopy showed that a large amount of xanthate species was adsorbed onto the sulfidized cuprite surfaces after pre-oxidation,which enhanced the cuprite hydrophobicity and improved the cuprite flotation.展开更多
DZ68 alloy is a new Ni-base directionally solidified superalloy for the blade of advanced turbine engine with high ratio of thrust-mass.In order to investigate the influence of pre-oxidation on the hot corrosion resis...DZ68 alloy is a new Ni-base directionally solidified superalloy for the blade of advanced turbine engine with high ratio of thrust-mass.In order to investigate the influence of pre-oxidation on the hot corrosion resistance of DZ68 alloy,pre-oxidation treatment was conducted at 950℃ in air for 20 h.A mixture of 75% Na2SO4 ＋25% NaCl （in mass fraction） was used for hot corrosion study at 900℃.The microstructure of specimens was investigated by using a scanning electron microscope （SEM） equipped with an energy dispersive spectroscopy （EDS）.The compositions of the corroded specimens were determined by X-ray diffraction （XRD）.After preoxidation at 950℃ in air for 20 h,a protective scale consisting of Cr2O3,Al2O3,NiO,NiCr2O4,and Ni2Ti4O formed on the DZ68 superalloy surface.The pre-oxidation treatment improved the initial incubation stage of the alloy in the mixture of 75% Na2SO4 ＋25% NaCl melts at 900℃.The oxide layer degraded gradually with increasing the time of hot corrosion.Once the oxide layer was damaged,the corrosion rate would increase rapidly,accompanied by obvious spallation of the corrosion products.At 900℃,the pre-oxidation treatment could not inhibit the accelerated hot corrosion of DZ68 in the mixture of 75% Na2SO4 ＋25% NaCl melts,with a high corrosion rate.展开更多
Magnetite is a kind of iron ore that is difficult to carburize.In order to improve the carburizing performance of magnetite pellet,pre-oxidation treatment was carried out,and the oxidation,reduction and carburization ...Magnetite is a kind of iron ore that is difficult to carburize.In order to improve the carburizing performance of magnetite pellet,pre-oxidation treatment was carried out,and the oxidation,reduction and carburization behaviors of magnetite pellet were investigated in this study.The magnetite pellet was oxidized in the air and carburized in CO-CO_(2)-H_(2) gas mixtures,the oxidation,reduction and carburization behaviors were demonstrated by detecting phase change,microstructure,carburizing index via thermogravimetry,X-ray diffraction(XRD),infrared carbon-sulfur analyzer,and scanning electron microscope(SEM).The results show that the dense magnetite particles inside pellet are oxidized to porous hematite particles,and the Fe_(3)O_(4) transforms to Fe_(2)O_(3) with high lattice defect concentration during the pre-oxidation process.Then the porous hematite particles and newly formed Fe_(2)O_(3) significantly promote the reduction efficiency.Porous metallic iron particles are produced in the reduction process.Finally,both high reduction efficiency and the porous structure of metallic iron particles dramatically enhance the carburization efficiency of pellet.High preoxidation temperature favors to the carburization of magnetite pellet.However,the carburized index decreases due to the recrystallization of iron oxide when the temperature extends to 1000℃.The optimum pre-oxidation temperature for magnetite pellet carburization is 900℃.展开更多
Hard carbon(HC)is broadly recognized as an exceptionally prospective candidate for the anodes of sodium-ion batteries(SIBs),but their practical implementation faces substantial limitations linked to precursor factors,...Hard carbon(HC)is broadly recognized as an exceptionally prospective candidate for the anodes of sodium-ion batteries(SIBs),but their practical implementation faces substantial limitations linked to precursor factors,such as reduced carbon yield and increased cost.Herein,a cost-effective approach is proposed to prepare a coal-derived HC anode with simple pre-oxidation followed by a post-carbonization process which effectively expands the d_(002)layer spacing,generates closed pores and increases defect sites.Through these modifications,the resulting HC anode attains a delicate equilibrium between plateau capacity and sloping capacity,showcasing a remarkable reversible capacity of 306.3 mAh·g^(-1)at 0.03 A·g^(-1).Furthermore,the produ ced HC exhibits fast reaction kinetics and exceptional rate performance,achieving a capacity of 289 mAh·g^(-1)at 0.1 A·g^(-1),equivalent to~94.5%of that at 0.03 A·g^(-1).When implemented in a full cell configuration,the impressive electrochemical performance is evident,with a notable energy density of 410.6 Wh·kg^(-1)(based on cathode mass).In short,we provide a straightforward yet efficient method for regulating coal-derived HC,which is crucial for the widespread use of SIBs anodes.展开更多
The stabilization of severely As-polluted soil has been a challenge, especially for the extremely toxic As(Ⅲ) contaminants. In this study, soil with a high As concentration(26084 mg/kg) was availably stabilized by a ...The stabilization of severely As-polluted soil has been a challenge, especially for the extremely toxic As(Ⅲ) contaminants. In this study, soil with a high As concentration(26084 mg/kg) was availably stabilized by a H2O2 pre-oxidation assisted TMT-15(Na3S3C3N3 solution with a mass fraction of 15%) and FeCl3·6 H2O stabilization method. The results showed that the combination of the two stabilizers(i.e., TMT-15 and FeCl3·6 H2O) presented a better stabilization behavior than either stabilizer used individually. The use of the H2O2 pre-oxidation assisted TMT-15 and FeCl3·6 H2O stabilization approach not only converted the As(Ⅲ) to As(Ⅴ) but also reduced the toxic leaching concentration of As to 1.61 mg/L, which is a safe level, when the additions of TMT-15 and FeCl3·6 H2O were 2 mL and 0.20 g, respectively. Thus, using only a simple H2O2 pre-oxidation to combine clean stabilization with non-toxic stabilizers TMT-15 and FeCl3·6 H2O could render the severely As-contaminated soil safe for disposal in a landfill.展开更多
The bacterial pre-oxidation process of arsenic-containing gold concentrates and the bacterial activity under different chloride ion concentrations were studied by using a mixture of thermophilic strains TCJ domesticat...The bacterial pre-oxidation process of arsenic-containing gold concentrates and the bacterial activity under different chloride ion concentrations were studied by using a mixture of thermophilic strains TCJ domesticated in production.The experimental result shows that with different samples and leaching systems,the adaptability and Cl- tolerance of bacteria are different,and that appropriate chloride ion concentration is conductive to bacterial oxidation,while higher chloride ion concentration will inhibit the bacterial activity and affect the pre-oxidation performance.Under the present production conditions,TCJ can adapt to the changes of water quality in the source of water and its critical chloride ion tolerance value is 2.7 g/L.展开更多
The hot corrosion behavior of Ti45 A18.5 Nb alloy was studied in the salt of Na_(2)SO_(4)and/or NaCl at 700℃.To improve the hot corrosion resistance,Ti45 A18.5 Nb alloy was anodized in fluorine-containing solution an...The hot corrosion behavior of Ti45 A18.5 Nb alloy was studied in the salt of Na_(2)SO_(4)and/or NaCl at 700℃.To improve the hot corrosion resistance,Ti45 A18.5 Nb alloy was anodized in fluorine-containing solution and pre-oxidized in air.Results showed that the combination of anodization and pre-oxidation can efficiently enhance the hot corrosion resistance of Ti45 A18.5 Nb alloy contaminated with Na_(2)SO_(4)or Na_(2)SO_(4)+NaCl deposits.This is because anodization and pre-oxidation result in the formation of compact AlOlayer which can act as a diffusion barrier to prevent sulfur,chlorine,and oxygen from attacking the alloy,therefore providing good resistance against hot corrosion.When exposed to NaCl deposit,however,no obvious improvement was achieved on the hot corrosion behavior no matter the alloy was anodized or further pre-oxidized in air.展开更多
The effect of treating algae-bearing water and induced odor by use of permanganate potassium composite （PPC） pre-oxidation was investigated, and was compared with the effect of treatments by pre-chlorination, perman...The effect of treating algae-bearing water and induced odor by use of permanganate potassium composite （PPC） pre-oxidation was investigated, and was compared with the effect of treatments by pre-chlorination, permanganate petassium pre-oxidation and simple coagulation. The results showed that simple coagulation and pre-chlorination were less effective in removing algae and its odor, whereas PPC pre-oxidation was the most effective in algae removal and deodorization. Upon oxidation with PPC, the cells of Oscillatoria agardhic were inactivated and some intra-cellular and extra-cellular components were released into the water, which may help the coagulation by their bridging effect. The efficient removal of algae by PPC pre-oxidation is believed to be the joint contribution of several mechanisms.展开更多
Zooplankton cyclops propagates profusely in waterbody, cannot be effectively inactivated by conventional disinfection process, and becomes a troublesome drinking water treatment problem. In this work, the qualitative ...Zooplankton cyclops propagates profusely in waterbody, cannot be effectively inactivated by conventional disinfection process, and becomes a troublesome drinking water treatment problem. In this work, the qualitative and quantitative experimental studies were carried out on inactivation of zooplankton cyclops using oxidants, such as chlorine （Cl2）, chlorine dioxide （ClO2）, ozone （O3）, hydrogen peroxide （H2O2）, ozone/hydrogen peroxide （O3/H2O2）, chloramines （Cl2-NH3） and potassium permanganate （KM4nO4）. The influences of various factors include different oxidant dosages, organic substance contents and pH values. The results showed that currently available oxidants used all might inactivate cyclops in some extent. According to the experimental results, chlorine dioxide, ozone, ozone/hydrogen peroxide and chloramines can be selected as effective oxidants for inactivating cyclops because of their strong inactivation abilities. Then the synergic removal effects on cyclops with ozone, ozone/hydrogen peroxide pre-oxidation followed by conventional water treatment processes were investigated, The results showed that ozone and ozone/hydrogen peroxide pre-oxidation can inactivate cyclops effectively, which then can be removed thoroughly by conventional water treatment processes. Cyclops cannot appear in water after filtration with 1.65 mg/L of ozone and 6 mg/L of hydrogen peroxide, with the inactivation rate being 62% before conventional water treatment processes. Cyclops cannot appear in water after filtration with 1.8 mg/L of ozone, with the inactivation rate being 50% before conventional water treatment processes. For different oxidants, when removal rate was the best, the inactivation rate was not the same. These results may provide reference and model for actual waterworks.展开更多
Pre-oxidation has been reported to be an effective way to remove algal cells in water, but the released algal organic matter (AOM) could be oxidized and lead to the increment in disinfection by-product (DBP) formation...Pre-oxidation has been reported to be an effective way to remove algal cells in water, but the released algal organic matter (AOM) could be oxidized and lead to the increment in disinfection by-product (DBP) formation. The relationship between pre-oxidation and AOM-derived DBP formation needs to be approached more precisely. This study compared the impact of four pre-oxidants, ozone (O), chlorine dioxide (ClO), potassium permanganate(KMnO) and sodium hypochlorite (NaClO), on the formation of nitrogenous (N-) and carbonaceous (C-) DBPs in AOM chlorination. The characterization (fluorescent properties,molecular weight distribution and amino acids concentration) on AOM samples showed that the characterization properties variations after pre-oxidation were highly dependent on the oxidizing ability of oxidants. The disinfection experiments showed that Oincreased DBP formation most significantly, which was consistent with the result of characterization properties variations. Then canonical correspondent analysis (CCA) and Pearson’s correlation analysis were conducted based on the characterization data and DBP formation. CCA indicated that C-DBPs formation was highly dependent on fluorescent data. The formation of haloacetic acids (HAAs) had a positive correlation with aromatic protein-like component while trichloromethane (TCM) had a positive correlation with fulvic acid-like component.Pearson’s correlation analysis showed that low molecular weight fractions were favorable to form N-DBPs. Therefore, characterization data could provide the advantages in the control of DBP formation, which further revealed that KMnOand ClOwere better options for removing algal cells as well as limiting DBP formation.展开更多
基金financially supported by the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(No.22KJA480004)the Key Laboratory of Flame Retardancy Finishing of Textile Materials,CNTAC(No.Q811580421)。
文摘Electrospun nanofibrous separators,despite lacking superior mechanical strength,have gained widespread attention with high porosity and facile processing.Herein,utilizing the fact that thermal imidization temperature of poly(amic acid)(PAA)into polyimide(PI)coincides with the pre-oxidation temperature of polyacrylonitrile(PAN)into carbon fiber,we proposed a new cross-electrospinning strategy to obtain a composite nanofibrous separator(PI/oPAN)randomly interwoven by PI and pre-oxidized PAN(oPAN)nanofibers,via synchronously electrospinning the PAA and PAN onto the same collector and then heat-treating for 2 h at 300℃.The resultant PI/oPAN separator was able to preserve high porosity(71.7%),electrolyte wettability and thermal stability of PI nanofibrous membrane,and surprisingly exhibited high mechanical strength,being 3 times of PI,which mainly because of the numerous adhesion points generated by the melting of PAN in the pre-oxidation process.Meanwhile,the polar groups of oPAN and 3D fibrous network enhanced the PI/oPAN separator's ionic conductivity and Li+transference number,rendering the corresponding cell with more stable cycling performance than cells assembled with pure PI,PAN or commercial PP separator.Therefore,this work might provide a new avenue for the ongoing design and further development of LIB separators capable of high safety and high performance.
基金Funded by the National Natural Science Foundation of China(51073098)the Open Project of State Key Laboratory of Polymer Materials Engineering(Sichuan University),China(KF200901)
文摘PAN fibers pre-oxidized at 240℃, 260℃, 280℃, 300℃ were treated in 8 T, 12 T, 16 T high magnetic fields, respectively. The experimental result implied that there were two kinds of magnetic units cyan and carbon-nitrogen heterocycle in pre-oxidized PAN fibers, and the movement of magnetic units resulted in changes of orientation structure of pre-oxidized PAN fibers in high magnetic fields. Overall orientation increased with increase of magnetic field intensity and extension of processing time, whereas change of crystalline orientation depended on magnetic field intensity and content of carbon-nitrogen heterocycle due to the competition of two magnetic units. Furthermore, magnetic fields induced the conversion from amorphous region to crystal region and improved crystalline orooerties of ore-oxidized PAN fibers.
基金Project(51304051)supported by the National Natural Science Foundation of ChinaProject(2012J05088)supported by the Natural Science Foundation of Fujian Province,China+1 种基金Project(022409)supported by School Talent Award of Fuzhou University,ChinaProject(2013-XQ-18)supported by Science&Technology Development Foundation of Fuzhou University,China
文摘Three representative sulfide ore samples were collected from typical metal mines,and their corresponding pre-oxidized products were obtained under nature environment.The thermal behaviors of each sample at heating rates of 5,10,15 and 20 °C/min in air flow from ambient temperature to 800 °C were studied by simultaneous thermal analysis and the TG/DSC curves before and after the pre-oxidation were compared.By the peak temperature of DTG curves,the whole reaction process for each sample was divided into different stages,and the apparent activation energies were calculated by the Ozawa-Flynn-Wall method.The results show that the reaction process of each sample after pre-oxidation is more complex,with quicker reaction rates,fewer heat production quantities,and higher or lower ignition-points.The apparent activation energies decrease from 364.017-474.228 kJ/mol to 244.523- 333.161 kJ/mol.Therefore,sulfide ores are more susceptible to spontaneous combustion after the pre-oxidation.
基金This work was supported by the National Natural Science Foundation of China(Grant No.U1902217).
文摘The effect of pre-oxidation degree of Panzhihua ilmenite concentrate on the gaseous reduction by carbon monoxide was investigated.The raw ilmenite concentrates were pre-oxidized at 600,700,800,900,and 1000°C for 2 h,respectively.The phase change,FeO content,and morphology after the oxidation at various temperatures were characterized.The oxidation degree was calculated according to the change of FeO content.Thermogravimetry was performed on the oxidized ilmenite concentrate samples(oxidized at 600,800,and 1000°C)at 850,900,and 950°C,respectively.The results show that the pre-oxidation of ilmenite concentrate can accelerate the reduction process:the higher pre-oxidation degree,the faster reduction rate.The high pre-oxidation degree of ilmenite concentrate is beneficial to accelerate the subsequent reduction process in two ways.Three stages of the reduction process were divided via the first derivatives of reduction degree,and the reduction mechanism and apparent activation energy were discussed subsequently.
基金supported by the National Natural Science Foundation of China(No.U22A20111).
文摘The corrosion behavior of the pre-oxidized GH4169 alloy was studied after 20 h of exposure under a solid NaCl deposit film in a wet O_(2) environment at 600℃ by mass-gain measurements,X-ray diffraction,scanning electron microscopy,transmission electron microscopy methods.The results indicate that the pre-oxidized GH4169 alloy undergoes serious corrosion in the corrosive condition.The preformed Cr_(2)O_(3) layer is gradually destroyed by deposit NaCl,and the inner Nb2O5 layer beneath the complete outer Cr_(2)O_(3) layer also reacts with NaCl to form NaNbO_(3).The electrochemical test results testified the existence of electrochemical reactions during this corrosion process.The corrosion behavior of pre-oxidized GH4169 under a solid NaCl deposit film in a wet O_(2) environment at 600℃has been discussed in detail.
基金supported by the National Natural Science Foundation of China(42167068,22269020)the Gansu Province Higher Education Industry Support Plan Project(2023CYZC-68)the Central Guidance for Local Science and Technology Development Funds Project(YDZX20216200001007)。
文摘Rationally regulating the porosity of hard carbon(HC),especially the closed pores matching the low potential plateau and the ultra-microporous structure suitable for Na+embedding,has been shown to be the key to improving the sodium storage performance and initial coulombic efficiency(ICE).However,the preparation of such HC materials with specific pore structures still faces great challenges.Herein,a simple pre-oxidation strategy is employed to construct abundant closed ultra-microporous structures in soy protein powder-derived HC material,achieving a significant improvement in its ICE and platform capacity.The pre-oxidation process promotes the cross-linking degree of the soy protein,thereby hindering the directional growth of graphite domains during the carbonization process.The optimized HC exhibits ultra-high platform capacity(329 mAh g^(-1))and considerable energy density(148.5 Wh kg^(-1)).Based on the ex-situ Raman and X-ray photoelectron spectroscopy characterization results,the excellent sodium storage capacity of the HC material is attributed to the synergistic effect of adsorption-intercalation/filling.The presented work provides novel insights into the synthesis of other biomass-derived HC materials with abundant closed ultra-micro pores.
基金Project supported the by State Key Laboratory of Internal Combustion Engines of Tianjin University,ChinaProject(51507077)supported by the National Natural Science Foundation of China+1 种基金Project(15KJB470005)supported by the Natural Science Research of Higher Education Institutions of Jiangsu Province,ChinaProjects(YKJ201308,QKJB201401)supported by Nanjing Institute of Technology,China
文摘The influence of the certain specific vacuum pre-oxidation process on the phase transformation of thermally-grown oxides（TGO） was studied.The CoCrAlY high temperature corrosion resistance coatings were produced onto the nickel-based superalloy substrate by high velocity oxygen fuel（HVOF）.It suggests that the TGO usually consists of a great number of chromium oxides,cobalt oxides and spinel oxides besides alumina during the initial period of the high temperature oxidation if the specimens are not subjected to the appropriate vacuum pre-oxidation process.Furthermore,the amount of alumina is strongly dependent on the partial pressure of oxygen;while the CoCr2O4 spinel oxides are usually formed under the conditions of higher partial pressure of oxygen during the initial period and the lower partial pressure of oxygen during the subsequent period of the isothermal oxidation.After the appropriate vacuum pre-oxidation process,the TGO is mainly composed of alumina that contains lower Y element,while alumina that contains higher Y element sporadically distributes,and the spinel oxides cannot be found.After a longer period of the isothermal oxidation,a small amount of porous CoCr2O4 and the chrome oxide sporadically distribute near the continuous alumina.Additionally,after the appropriate vacuum pre-oxidation process,the TGO growth rate is relatively slow.
基金Project (2006AA06Z132) supported by High-tech Research and Development Program of ChinaProject (B604) supported by Leading Academic Discipline Project of Shanghai
文摘An artificial neural network model was developed to predict the oxidation of refractory gold concentrate （RGC） by ozone and ferric ions. The concentration of ozone and ferric ions, pulp density, oxygen amount, leaching time and temperature were employed as inputs to the network; the output of the network was the percentage of the ferric extraction iron from RGC. The multilayered feed-forward networks were trained by 33 sets of input-output patterns using a back propagation algorithm; a three-layer network with 8 neurons in the hidden layer gave optimal results. The model gave good predictions of high correlation coefficient （R2=0.966）. The predictions by ANN are more accurate when compared with conventional multivariate regression analysis （MVRA）. In addition, calculation with ANN model indicates that temperature is the predominant parameter and ozone concentration is the lesser influential parameter in the pre-oxidation process of refractory gold ore. The ANN neural network model accurately estimates the ferric extraction during pretreatment process of RGC in gold smelter plants and can be used to optimize the process parameters.
基金supported by the National Natural Science Foundation of China (No. 22179094)。
文摘Due to its low cost and easy availability, the pitch is considered a promising precursor for soft carbon anodes. However, pitch-derived soft carbon shows a high graphitization degree and small interlayer spacing, resulting in its much lower sodium storage performance than hard carbon. We propose a novel preoxidation strategy to introduce additional oxygen atoms into the low-cost soft carbon precursor pitch to fabricate a defect-rich and large-interlayer spacing hard carbon anode(HPP-1100). Compared with the direct pyrolysis of pitch carbon, the sodium storage capacity of HPP-1100 is significantly improved from 120.3 m Ah/g to 306.7 m Ah/g, with an excellent rate and cycling capability(116.5 m Ah/g at 10 C). Moreover, when assorted with an O_(3)-Na(NiFeMn)1/3O_(2)cathode, the full cell delivers a high reversible capacity of 274.0 m Ah/g at 0.1 C with superb cycle life. This work provides a new solution for realizing the application of low-cost pitch anodes in Na-ion batteries.
基金supported by the National Key Research and Development Project (No. 2018YFE0204101)National Natural Science Foundation of China (No. 51808531)。
文摘Cyanobacterial bloom has many adverse effects on source water quality and drinking water production. The traditional water treatment process can hardly achieve satisfactory removal of algae cells. This review examines the impact of pre-oxidation on the removal of cyanobacteria by solid-liquid separation processes. It was reported that the introduction of chemical oxidants such as chlorine, potassium permanganate, and ozone in algae-laden water pretreatment could improve algae removal by the subsequent solid-liquid separation processes. However, over dosed oxidants can result in more serious water quality risks due to significant algae cell lysis and undesirable intracellular organic matter release. It was suggested that moderate pre-oxidation may enhance the removal of cyanobacteria without damaging algae cells. In this article, effects of moderate pretreatment on the solid-liquid separation processes(sedimentation, dissolved air flotation, and membrane filtration) are reviewed.
基金the Project funded by Ten Thousand Talent Plans for Young Top-notch Talents of Yunnan Province (Grant No. YNWR-QNBJ-2018-051)。
文摘The direct sulfidization of cuprite is inefficient because cuprite is a copper-oxide mineral with a strong surface hydrophilicity.In this study,oxidant was used to modify cuprite surfaces to regulate the sulfidization of cuprite.Microflotation tests showed that the flotation recovery of pre-oxidized cuprite was nearly25% higher than that of direct sulfidization flotation,which indicates that the cuprite surface activity was enhanced after pre-oxidation by Cu(Ⅰ) species(weak affinity with sulfur ions) transformation to Cu(Ⅱ)species(strong affinity with sulfur ions).Zeta potential,scanning electron microscopy-energy dispersive X-ray spectroscopy,X-ray photoelectron spectroscopy,and time-of-flight secondary ion mass spectrometry results showed that pre-oxidation improved cuprite sulfidization and promoted the formation of copper-sulfide species on the cuprite surfaces.The mineral surface stability and thus,xanthate species adsorption on the cuprite surfaces were improved.The surface-adsorption measurements and infrared spectroscopy showed that a large amount of xanthate species was adsorbed onto the sulfidized cuprite surfaces after pre-oxidation,which enhanced the cuprite hydrophobicity and improved the cuprite flotation.
文摘DZ68 alloy is a new Ni-base directionally solidified superalloy for the blade of advanced turbine engine with high ratio of thrust-mass.In order to investigate the influence of pre-oxidation on the hot corrosion resistance of DZ68 alloy,pre-oxidation treatment was conducted at 950℃ in air for 20 h.A mixture of 75% Na2SO4 ＋25% NaCl （in mass fraction） was used for hot corrosion study at 900℃.The microstructure of specimens was investigated by using a scanning electron microscope （SEM） equipped with an energy dispersive spectroscopy （EDS）.The compositions of the corroded specimens were determined by X-ray diffraction （XRD）.After preoxidation at 950℃ in air for 20 h,a protective scale consisting of Cr2O3,Al2O3,NiO,NiCr2O4,and Ni2Ti4O formed on the DZ68 superalloy surface.The pre-oxidation treatment improved the initial incubation stage of the alloy in the mixture of 75% Na2SO4 ＋25% NaCl melts at 900℃.The oxide layer degraded gradually with increasing the time of hot corrosion.Once the oxide layer was damaged,the corrosion rate would increase rapidly,accompanied by obvious spallation of the corrosion products.At 900℃,the pre-oxidation treatment could not inhibit the accelerated hot corrosion of DZ68 in the mixture of 75% Na2SO4 ＋25% NaCl melts,with a high corrosion rate.
基金Project(U1960104)supported by the National Natural Science Foundation of ChinaProject(LYU Ya-nan)supported by the Jiangsu Colleges and Universities Qing Lan Project,China。
文摘Magnetite is a kind of iron ore that is difficult to carburize.In order to improve the carburizing performance of magnetite pellet,pre-oxidation treatment was carried out,and the oxidation,reduction and carburization behaviors of magnetite pellet were investigated in this study.The magnetite pellet was oxidized in the air and carburized in CO-CO_(2)-H_(2) gas mixtures,the oxidation,reduction and carburization behaviors were demonstrated by detecting phase change,microstructure,carburizing index via thermogravimetry,X-ray diffraction(XRD),infrared carbon-sulfur analyzer,and scanning electron microscope(SEM).The results show that the dense magnetite particles inside pellet are oxidized to porous hematite particles,and the Fe_(3)O_(4) transforms to Fe_(2)O_(3) with high lattice defect concentration during the pre-oxidation process.Then the porous hematite particles and newly formed Fe_(2)O_(3) significantly promote the reduction efficiency.Porous metallic iron particles are produced in the reduction process.Finally,both high reduction efficiency and the porous structure of metallic iron particles dramatically enhance the carburization efficiency of pellet.High preoxidation temperature favors to the carburization of magnetite pellet.However,the carburized index decreases due to the recrystallization of iron oxide when the temperature extends to 1000℃.The optimum pre-oxidation temperature for magnetite pellet carburization is 900℃.
基金financially supported by the National Natural Science Foundation of China(No.52173246)111 project(No.B13013)Shccig-Qinling Program(No.SMYJY20220574)。
文摘Hard carbon(HC)is broadly recognized as an exceptionally prospective candidate for the anodes of sodium-ion batteries(SIBs),but their practical implementation faces substantial limitations linked to precursor factors,such as reduced carbon yield and increased cost.Herein,a cost-effective approach is proposed to prepare a coal-derived HC anode with simple pre-oxidation followed by a post-carbonization process which effectively expands the d_(002)layer spacing,generates closed pores and increases defect sites.Through these modifications,the resulting HC anode attains a delicate equilibrium between plateau capacity and sloping capacity,showcasing a remarkable reversible capacity of 306.3 mAh·g^(-1)at 0.03 A·g^(-1).Furthermore,the produ ced HC exhibits fast reaction kinetics and exceptional rate performance,achieving a capacity of 289 mAh·g^(-1)at 0.1 A·g^(-1),equivalent to~94.5%of that at 0.03 A·g^(-1).When implemented in a full cell configuration,the impressive electrochemical performance is evident,with a notable energy density of 410.6 Wh·kg^(-1)(based on cathode mass).In short,we provide a straightforward yet efficient method for regulating coal-derived HC,which is crucial for the widespread use of SIBs anodes.
基金financially supported by the National Key R&D Program of China (No. 2018YFC1802400)the National Natural Science Foundation of China (No. 51604310)+1 种基金the Major Project of Central Research Institute of Building and Construction (No. XAC2017Ky03)the Opening Foundation of State Key Laboratory for Environmental Protection of Iron and Steel Industry (No. 2016YZC02)
文摘The stabilization of severely As-polluted soil has been a challenge, especially for the extremely toxic As(Ⅲ) contaminants. In this study, soil with a high As concentration(26084 mg/kg) was availably stabilized by a H2O2 pre-oxidation assisted TMT-15(Na3S3C3N3 solution with a mass fraction of 15%) and FeCl3·6 H2O stabilization method. The results showed that the combination of the two stabilizers(i.e., TMT-15 and FeCl3·6 H2O) presented a better stabilization behavior than either stabilizer used individually. The use of the H2O2 pre-oxidation assisted TMT-15 and FeCl3·6 H2O stabilization approach not only converted the As(Ⅲ) to As(Ⅴ) but also reduced the toxic leaching concentration of As to 1.61 mg/L, which is a safe level, when the additions of TMT-15 and FeCl3·6 H2O were 2 mL and 0.20 g, respectively. Thus, using only a simple H2O2 pre-oxidation to combine clean stabilization with non-toxic stabilizers TMT-15 and FeCl3·6 H2O could render the severely As-contaminated soil safe for disposal in a landfill.
基金Project(2007AA060902) supported by the National High Technology Research and Development Program of ChinaProject(2010CB630905) supported by the National Basic Research Program of China
文摘The bacterial pre-oxidation process of arsenic-containing gold concentrates and the bacterial activity under different chloride ion concentrations were studied by using a mixture of thermophilic strains TCJ domesticated in production.The experimental result shows that with different samples and leaching systems,the adaptability and Cl- tolerance of bacteria are different,and that appropriate chloride ion concentration is conductive to bacterial oxidation,while higher chloride ion concentration will inhibit the bacterial activity and affect the pre-oxidation performance.Under the present production conditions,TCJ can adapt to the changes of water quality in the source of water and its critical chloride ion tolerance value is 2.7 g/L.
基金supported by the National Natural Science Foundation of China(No.51971205)the Guangdong Basic and Applied Basic Research Foundation(No.2021B1515020056)the Basic Research Project of Shenzhen Science and Technology Innovation Program(No.JCYJ20190807154005593)。
文摘The hot corrosion behavior of Ti45 A18.5 Nb alloy was studied in the salt of Na_(2)SO_(4)and/or NaCl at 700℃.To improve the hot corrosion resistance,Ti45 A18.5 Nb alloy was anodized in fluorine-containing solution and pre-oxidized in air.Results showed that the combination of anodization and pre-oxidation can efficiently enhance the hot corrosion resistance of Ti45 A18.5 Nb alloy contaminated with Na_(2)SO_(4)or Na_(2)SO_(4)+NaCl deposits.This is because anodization and pre-oxidation result in the formation of compact AlOlayer which can act as a diffusion barrier to prevent sulfur,chlorine,and oxygen from attacking the alloy,therefore providing good resistance against hot corrosion.When exposed to NaCl deposit,however,no obvious improvement was achieved on the hot corrosion behavior no matter the alloy was anodized or further pre-oxidized in air.
文摘The effect of treating algae-bearing water and induced odor by use of permanganate potassium composite （PPC） pre-oxidation was investigated, and was compared with the effect of treatments by pre-chlorination, permanganate petassium pre-oxidation and simple coagulation. The results showed that simple coagulation and pre-chlorination were less effective in removing algae and its odor, whereas PPC pre-oxidation was the most effective in algae removal and deodorization. Upon oxidation with PPC, the cells of Oscillatoria agardhic were inactivated and some intra-cellular and extra-cellular components were released into the water, which may help the coagulation by their bridging effect. The efficient removal of algae by PPC pre-oxidation is believed to be the joint contribution of several mechanisms.
基金Project supported by the Hi-Tech Research and Development Program (863) of China (No. 2006AA06Z311)the Postdoctoral Science Foundation of Heilongjiang Province (No. LRB05-164)the Excellent Young Teacher Encouragement Project Foundation of HIT(No. HIT2006), China
文摘Zooplankton cyclops propagates profusely in waterbody, cannot be effectively inactivated by conventional disinfection process, and becomes a troublesome drinking water treatment problem. In this work, the qualitative and quantitative experimental studies were carried out on inactivation of zooplankton cyclops using oxidants, such as chlorine （Cl2）, chlorine dioxide （ClO2）, ozone （O3）, hydrogen peroxide （H2O2）, ozone/hydrogen peroxide （O3/H2O2）, chloramines （Cl2-NH3） and potassium permanganate （KM4nO4）. The influences of various factors include different oxidant dosages, organic substance contents and pH values. The results showed that currently available oxidants used all might inactivate cyclops in some extent. According to the experimental results, chlorine dioxide, ozone, ozone/hydrogen peroxide and chloramines can be selected as effective oxidants for inactivating cyclops because of their strong inactivation abilities. Then the synergic removal effects on cyclops with ozone, ozone/hydrogen peroxide pre-oxidation followed by conventional water treatment processes were investigated, The results showed that ozone and ozone/hydrogen peroxide pre-oxidation can inactivate cyclops effectively, which then can be removed thoroughly by conventional water treatment processes. Cyclops cannot appear in water after filtration with 1.65 mg/L of ozone and 6 mg/L of hydrogen peroxide, with the inactivation rate being 62% before conventional water treatment processes. Cyclops cannot appear in water after filtration with 1.8 mg/L of ozone, with the inactivation rate being 50% before conventional water treatment processes. For different oxidants, when removal rate was the best, the inactivation rate was not the same. These results may provide reference and model for actual waterworks.
基金supported by the National Natural Science Foundation (Nos. 51878257, 52100007)the Natural Science Foundation of Hunan Province (No. 2021JJ40066) and the Natural Science Foundation of Hunan Province (No. 2021JJ40106)。
文摘Pre-oxidation has been reported to be an effective way to remove algal cells in water, but the released algal organic matter (AOM) could be oxidized and lead to the increment in disinfection by-product (DBP) formation. The relationship between pre-oxidation and AOM-derived DBP formation needs to be approached more precisely. This study compared the impact of four pre-oxidants, ozone (O), chlorine dioxide (ClO), potassium permanganate(KMnO) and sodium hypochlorite (NaClO), on the formation of nitrogenous (N-) and carbonaceous (C-) DBPs in AOM chlorination. The characterization (fluorescent properties,molecular weight distribution and amino acids concentration) on AOM samples showed that the characterization properties variations after pre-oxidation were highly dependent on the oxidizing ability of oxidants. The disinfection experiments showed that Oincreased DBP formation most significantly, which was consistent with the result of characterization properties variations. Then canonical correspondent analysis (CCA) and Pearson’s correlation analysis were conducted based on the characterization data and DBP formation. CCA indicated that C-DBPs formation was highly dependent on fluorescent data. The formation of haloacetic acids (HAAs) had a positive correlation with aromatic protein-like component while trichloromethane (TCM) had a positive correlation with fulvic acid-like component.Pearson’s correlation analysis showed that low molecular weight fractions were favorable to form N-DBPs. Therefore, characterization data could provide the advantages in the control of DBP formation, which further revealed that KMnOand ClOwere better options for removing algal cells as well as limiting DBP formation.
