The prediction of sea surface partial pressure of carbon dioxide(pCO_(2))in the South China Sea is crucial for understanding the region’s contribution to the global carbon budget and its interactions with climate cha...The prediction of sea surface partial pressure of carbon dioxide(pCO_(2))in the South China Sea is crucial for understanding the region’s contribution to the global carbon budget and its interactions with climate change.We applied the Spatiotemporal Convolutional Long Short-Term Memory(STConvLSTM)model,integrating key environmental factors including sea surface temperature(SST),sea surface salinity(SSS),and chlorophyll a(Chl a),to predict and analyze sea surface pCO_(2)in the South China Sea.The model demonstrated high accuracy in short-term predictions(1 month),with a mean absolute error(MAE)of 0.394,a root mean square error(RMSE)of 0.659,and a coefficient of determination(R^(2))of 0.998.For long-term predictions(12 months),the model maintained its predictive capability,with an MAE of 0.667,RMSE of 1.255,and R^(2)of 0.994.Feature importance analysis revealed that sea surface pCO_(2)and SST were the main drivers of the model’s predictions,whereas Chl a and SSS had relatively minor impacts.The model’s generalization ability was further validated in the northwest Pacific Ocean and tropical Pacific Ocean,where it successfully captured the spatiotemporal variation in pCO_(2)with small prediction errors.The ST-ConvLSTM model provides an efficient and accurate tool for forecasting and analyzing sea surface pCO_(2)in the South China Sea,offering new insights into global carbon cycling and climate change.This study demonstrates the potential of deep learning in marine science and provides a significant technical support for global changes and marine ecosystem research.展开更多
The global distributions of the air-sea CO2 transfer velocity and flux are retrieved from TOPEX/Poseidon and Jason altimeter data from October 1992 to December 2009 using a combined algorithm. The 17 a average global,...The global distributions of the air-sea CO2 transfer velocity and flux are retrieved from TOPEX/Poseidon and Jason altimeter data from October 1992 to December 2009 using a combined algorithm. The 17 a average global, area-weighted, Schmidt number-corrected mean gas transfer velocity is 21.26 cm/h, and the full exploration of the uncertainty of this estimate awaits further data. The average total CO2 flux （calculated by carbon） from atmosphere to ocean during the 17 a was 2.58 Pg/a. The highest transfer velocity is in the circumpolar current area, because of constant high wind speeds and currents there. This results in strong CO2 fluxes. CO2 fluxes are strong but opposite direction in the equatorial east Pacific Ocean, because the air-sea CO2 partial pressure difference is the largest in the global cceans. The results differ from the previous studies calculated using the wind speed. It is demonstrated that the air-sea transfer velocity is very important for estimating air-sea CO2 flux. It is critical to have an accurate estimation for improving calculation of CO2 flux within climate change studies.展开更多
Due to the important role of oil source in our life,the separation of water-in-oil emulsion is urgent and necessary.Membrane seperation technology has been an efficient and widely used method in separating oil-water s...Due to the important role of oil source in our life,the separation of water-in-oil emulsion is urgent and necessary.Membrane seperation technology has been an efficient and widely used method in separating oil-water separation.Herein,we report a versatile approach to fabricate surface carbonized membranes with self-standing property from biomass-derived precursor by synergistic charring of phytic acid,arginine and filter paper.The obtained membrane exhibited superhydrophobicity in oil,excellent fouling resistance,and self-supporting ability.The membrane can be cycle-used at least 12 times with high permeation flux(up to 1380 L·m^(-2)·h^(-1))and separation efficiency(up to 99.4%).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
Polyacrylonitrile （PAN） based carbon fibers with different surface morphology were electrochemically treated in 3 wt% NH4HCO3 aqueous solution with current density up to 3.47 A/m 2 at room temperature, and surface s...Polyacrylonitrile （PAN） based carbon fibers with different surface morphology were electrochemically treated in 3 wt% NH4HCO3 aqueous solution with current density up to 3.47 A/m 2 at room temperature, and surface structures, surface morphology and residual mechanical properties were characterized. The crystallite size （La） of carbon fibers would be interrupted due to excessive electrochemical etching, while the crystallite spacing （d（002）） increased as increasing current density. The disordered structures on the surface of carbon fiber with rough surface increased at the initial oxidation stage and then removed by further electrochemical etching, which resulting in continuous increase of the extent of graphitization on the fiber surface. However, the electrochemical etching was beneficial to getting ordered morphology on the surface for carbon fiber with smooth surface, especially when the current density was lower than 1.77 A/m 2 . The tensile strength and tensile modulus could be improved by 17.27% and 5.75%, respectively, and was dependent of surface morphology. The decreasing density of carbon fibers probably resulted from the volume expansion of carbon fibers caused by the abundant oxygen functional groups intercalated between the adjacent graphite layers.展开更多
Sodium carbonate and carboxymethyl cellulose powders are compressed into two-component tablets with three mass ratios,97%:3%,95%:5% and 93%:7%.The dissolution tests for two-component tablets and reference pure sodium ...Sodium carbonate and carboxymethyl cellulose powders are compressed into two-component tablets with three mass ratios,97%:3%,95%:5% and 93%:7%.The dissolution tests for two-component tablets and reference pure sodium carbonate tablets are carried out at various temperatures.The dissolution process of each tablet is measured by electrical conductivity tracking method and the concentration of dissolved sodium carbonate is quanti fied with calibrated conductivity-concentration converting equation of sodium carbonate.The quanti fied dissolution data is fitted with both surface reaction model and diffusion layer model and the results clearly show that surface reaction model is suggested as the appropriate dissolution model for all measured tablets.Therefore,it is determined that carboxymethyl cellulose is a stable element to remain the dissolution mechanism of tablet unchanged.The dissolution rate constant quanti fied with surface reaction model presents that carboxymethyl cellulose-sodium carbonate two-component tablets obtain signi ficant higher dissolution rate constant than pure sodium carbonate tablet and higher proportion of carboxymethyl cellulose leads to apparent higher dissolution rate constant.The results prove for the usage of carboxymethyl cellulose in most practical applications at a relative low-level,the effect of carboxymethyl cellulose is effective and positive for two-component tablet to enhance the dissolution process and improve dissolution rate constant and this effect is speculated coming from its dynamic physical transforming process in water including dilation and conglutination.展开更多
Periodic density functional theory calculations have been performed to investigate the chemisorption behavior of COz molecule on a series of surface alloys that are built by dispersing individual middle-late transitio...Periodic density functional theory calculations have been performed to investigate the chemisorption behavior of COz molecule on a series of surface alloys that are built by dispersing individual middle-late transition metal （TM） atoms （TM = Fe, Co, Ni, Ru, Rh, Pd, Ag, Os, lr, Pt, Au） on the Cu（100） and Cu（lll） surfaces. The most stable configurations of CO2 chemisorbed on different TM/Cu surfaces are determined, and the results show that among the late transition metals, Co, Ru, and Os are potentially good dopants to enhance the chemisorption and activation of CO2 on copper surfaces. To obtain a deep understanding of the adsorption property, the bonding characteristics of the adsorption bonds are carefully examined by the crystal orbital Hamilton population technique, which reveals that the TM atom primarily provides d orbitals with z-component, namely dz2, dxz, and dvz orbitals to interact with the adsorbate.展开更多
The carbon layers on implanted steel surface have been studied by means of Auger spectra. It is shown that the thickness of the carbon layer is proportional to the dose of implanted ions. By comparison with the result...The carbon layers on implanted steel surface have been studied by means of Auger spectra. It is shown that the thickness of the carbon layer is proportional to the dose of implanted ions. By comparison with the results of friction and wear tests, the friction coefficient is smaller than 0.20 at the first part of the friction coefficient curve. It is considered that the graphitic carbon layer on the top of steel is helpful to reducing the surface friction coefficient of steel.展开更多
In this letter ab initio electronic structure calculations are performed for extensive geometries Of CS2. A newly written program is used to fit the computed energies into the Sorbie-Murrel function, whose contour plo...In this letter ab initio electronic structure calculations are performed for extensive geometries Of CS2. A newly written program is used to fit the computed energies into the Sorbie-Murrel function, whose contour plots are illustrated.展开更多
Surface functionalization of carbon nanofibers（CNFs） was carried out, i e, CNFs were firstly oxidized and then the surface was silanized by 3-Aminopropyltriethoxysilane（APTES） via an assembly method. A new kind of...Surface functionalization of carbon nanofibers（CNFs） was carried out, i e, CNFs were firstly oxidized and then the surface was silanized by 3-Aminopropyltriethoxysilane（APTES） via an assembly method. A new kind of high wear resistance s-CNFs/epoxy composite was fabricated by in-situ reaction. FTIR spectroscopy was used to detect the changes of the functional groups produced by silane on the surface of CNFs. The tribological properties and microstructures of modified and unmodified CNFs/epoxy composites were studied, respectively. The expremental results indicate that APTES is covalently linked to the surface of CNFs successfully and improves the dispersion of CNF in epoxy matrix. The friction coefficients and the wear rates of s-CNFs/epoxy composites are evidently lower than those of u-CNFs/epoxy composites under the same loads. Investigations also indicate that abrasive wear is the main wear mechanism for u-CNFs/epoxy composite, with slight adhesive wear for s-CNFs/epoxy composite under the same sliding wear condition.展开更多
Carbon deposition on nickel powders in methane involves three stages in different reaction temperature ranges. Temperature programing oxidation test and Raman spectrum results indicated the formation of complex and or...Carbon deposition on nickel powders in methane involves three stages in different reaction temperature ranges. Temperature programing oxidation test and Raman spectrum results indicated the formation of complex and ordered carbon structures at high deposition temperatures. The values of I（D）/I（G） of the deposited carbon reached 1.86, 1.30, and 1.22 in the first, second, and third stages, respectively. The structure of carbon in the second stage was similar to that in the third stage. Carbon deposited in the first stage rarely contained homogeneous pyrolytic deposit layers. A kinetic model was developed to analyze the carbon deposition behavior in the first stage. The rate-determining step of the first stage is supposed to be interfacial reaction. Based on the investigation of carbon deposition kinetics on nickel powders from different resources, carbon deposition rate is suggested to have a linear relation with the square of specific surface area of nickel particles.展开更多
Addressing global warming,a common change today,requires achieving peak carbon dioxide emissions and carbon neutrality(also referred to as the dual carbon goals).Enhancing research on the carbon cycle is urgently need...Addressing global warming,a common change today,requires achieving peak carbon dioxide emissions and carbon neutrality(also referred to as the dual carbon goals).Enhancing research on the carbon cycle is urgently needed as the foundation.Water,a key carrier in the carbon cycle,necessitates investigation into groundwater carbon pools’contribution to atmospheric carbon sinks.This study assessed carbon stocks in the Yinchuan Basin’s soil and groundwater carbon pools.Findings indicate the basin’s surface soils contain approximately 24.16 Tg of organic carbon and a total of 60.01 Tg of carbon.In contrast,the basin’s groundwater holds around 4.90 Tg of carbon,roughly one-fifth of the organic carbon in surface soils.Thus,groundwater and soil carbon pools possess comparable carbon stocks,underscoring the importance of the groundwater carbon pool.Studies on terrestrial carbon balance should incorporate groundwater carbon pools,which deserve increased focus.Evaluating groundwater carbon pools’contributions is vital for achieving the dual carbon goals.展开更多
A series of high surface area graphitic carbon materials （HSGCs） were prepared by ball-milling method. Effect of the graphitic degree of HSGCs on the catalytic performance of Ba-Ru-K/HSGC-x （x is the ball-milling t...A series of high surface area graphitic carbon materials （HSGCs） were prepared by ball-milling method. Effect of the graphitic degree of HSGCs on the catalytic performance of Ba-Ru-K/HSGC-x （x is the ball-milling time in hour） catalysts was studied using ammonia synthesis as a probe reaction. The graphitic degree and pore structure of HSGC-x supports could be successfully tuned via the variation of ball-milling time. Ru nanoparticles of different Ba-Ru-K/HSGC-x catalysts are homogeneously distributed on the supports with the particle sizes ranging from 1.6 to 2.0 nm. The graphitic degree of the support is closely related to its facile electron transfer capability and so plays an important role in improving the intrinsic catalytic performance of Ba-Ru-K/HSGC-x catalyst.展开更多
Taming the electron transfer across metal–support interfaces appears to be an attractive yet challenging methodology to boost catalytic properties.Herein,we demonstrate a precise engineering strategy for the carbon s...Taming the electron transfer across metal–support interfaces appears to be an attractive yet challenging methodology to boost catalytic properties.Herein,we demonstrate a precise engineering strategy for the carbon surface chemistry of Pt/C catalysts—that is,for the electron-withdrawing/donating oxygencontaining groups on the carbon surface—to fine-tune the electrons of the supported metal nanoparticles.Taking the ammonia borane hydrolysis as an example,a combination of density functional theory(DFT)calculations,advanced characterizations,and kinetics and isotopic analyses reveals quantifiable relationships among the carbon surface chemistry,Pt charge state and binding energy,activation entropy/enthalpy,and resultant catalytic activity.After decoupling the influences of other factors,the Pt charge is unprecedentedly identified as an experimentally measurable descriptor of the Pt active site,contributing to a 15-fold increment in the hydrogen generation rate.Further incorporating the Pt charge with the number of Pt active sites,a mesokinetics model is proposed for the first time that can individually quantify the contributions of the electronic and geometric properties to precisely predict the catalytic performance.Our results demonstrate a potentially groundbreaking methodology to design and manipulate metal–carbon catalysts with desirable properties.展开更多
A series of activated carbons from Taixi anthracite were prepared by steam activation in the presence of KOH and then they were modified by different methods. The regulation of porosity and the modification of surface...A series of activated carbons from Taixi anthracite were prepared by steam activation in the presence of KOH and then they were modified by different methods. The regulation of porosity and the modification of surface chemistry were carried out with the aim to improve the benzene adsorption capacity of activated carbon. The influences of KOH and activation process parameters including activation temperature, activation time and steam flow rate on porosity of activated carbon were evaluated, and the effect of modification methods on surface chemistry was investigated. Also, the relationship between benzene adsorption capacity and porosity and surface chemistry was analyzed. Results show that activation temperature is the dominant factor in the activation process; the introduction of KOH into the raw material can enhance the reactivity of char in activation process, meanwhile it shows a negative effect on the porosity development, especially on the mesopore development. Results of FTIR analysis indicate that anthracite-based activated carbon with condensed aromatics and chemically inert oxygen does not present the nature to be surface modified. Besides, benzene adsorption capacity has an approximate linear relationship with surface area and in our preparation, benzene adsorption capacity and surface area of activated carbon are up to 1210 m 2 /g and 423 mg/g, respectively.展开更多
Facile production of high quality activated carbons from biomass materials has greatly triggered much attention presently. In this paper, a series of interconnected porous carbon materials from lotus root shells bioma...Facile production of high quality activated carbons from biomass materials has greatly triggered much attention presently. In this paper, a series of interconnected porous carbon materials from lotus root shells biomass are prepared via simple pyrolysis and followed by a KOH activation process. The prepared carbons exhibit high specific surface areas of up to 2961 m^2/g and large pore volume～1.47 cm3/g. In addition, the resultant porous carbons served as electrode materials in supercapacitor exhibit high specific capacitance and outstanding recycling stability and high energy density. In particular, their specific capacitance retention was almost 100% after 10500 cycles at a current density of 2 A/g. Remarkabely, the impact of the tailored specific surface areas of various carbon samples on their capacitive performances is systematically investigated.Generally, it was believed that the highly-developed porosity features（including surface areas and pore volume and pore size-distributions）, together with the good conductivity of activated carbon species, play a key role in effectively improving the storage energy performances of the porous carbon electrode materials in supercapacitor.展开更多
Herein, we report a simple and effective preparation of ultrafine CNFs （u-CNFs） with high surface area via electrospinning of two immiscible polymers [polyacrylonitrile （PAN） and poly（methyl methacry- late） （P...Herein, we report a simple and effective preparation of ultrafine CNFs （u-CNFs） with high surface area via electrospinning of two immiscible polymers [polyacrylonitrile （PAN） and poly（methyl methacry- late） （PMMA）] followed by calcination at high temperature in an inert atmosphere. Various electrospinning conditions were optimized in detail. Four different kinds of PAN/PMMA ratios （10/0, 7：3, 5：5 and 3：7） were chosen and found that the PAN/PMMA ratio of 3：7 （PAN/PMMA-3：7） is the optimum one. BET anal- ysis showed the specific surface area of the u-CNFs-3：7 was 46Z57 m2/g with an excellent pore volume （1.15 cms g-l） and an average pore size （9.48 nm）： it is about 25 times higher than the conventional CNFs （c-CNFs）. TEM and FE-SEM images confirmed the ultrafine structure of the CNFs with a thinner fiber di- ameter of-50 nm. The graphitic nature and atomic arrangement of the u-CNFs were investigated by Raman and XPS analyses. For the supercapacitor application, unlike the common electrode preparation methods, the u-CNFs-3：7 was used without any activation, chemical or mechanical modifications. The u-CNFs- 3：7 showed a better specific capacitance of 86 Fig in 1 mol/L 1-12S04 when compared to pure CNFs. The excellent physicochemical properties make the u-CNFs-3：7 an alternative choice to the existing CNFs for the supercapacitors.展开更多
Multi-walled carbon nanotubes（CNTs） were modified by an amination treatment with hexamethylenediamine（HMD）, and then bismaleimide（BMI）/epoxy（E-44）/CNTs ternary composites were prepared using modified CNTs as t...Multi-walled carbon nanotubes（CNTs） were modified by an amination treatment with hexamethylenediamine（HMD）, and then bismaleimide（BMI）/epoxy（E-44）/CNTs ternary composites were prepared using modified CNTs as the reinforcement via a simple mixing and curing molding method. The results show that the surfaces of CNTs are grafted polymer with the thickness of 3 nm and the dispersity of surface grafted carbon nanotubes（SG-CNTs） in the resin composites can be improved. The prepared composites contain C-C, C-N, C=O and-COOH groups and can keep a smooth surface. In addition, the composites have the flexural strength of 152 MPa, the tensile strength of 73 MPa and the impact strength of 87 k J m^（-2）,respectively, when the weight ratio of BMI to E-44 is 1：8 and the content of SG-CNTs is 2 wt%. However,the thermal stability of the composites with SG-CNTs is a little lower than that of the composites without SG-CNTs.展开更多
Soil carbon sequestration and potential has been a focal issue in global carbon research. Under the background of global change, the estimation of the size as well as its change of soil organic carbon（SOC） storage i...Soil carbon sequestration and potential has been a focal issue in global carbon research. Under the background of global change, the estimation of the size as well as its change of soil organic carbon（SOC） storage is of great importance. Based on soil data from the second national soil survey and field survey during 2011–2012, by using the regression method between sampling soil data and remote sensing data, this paper aimed to investigate spatial distribution and changes of topsoil（0–20 cm） organic carbon storage in grasslands of Inner Mongolia between the 1980 s and 2010 s. The results showed that：（1） the SOC storage in grasslands of Inner Mongolia between the 1980 s and 2010 s was estimated to be 2.05 and 2.17 Pg C, with an average density of 3.48 and 3.69 kg C·m–2, respectively. The SOC storage was mainly distributed in the typical steppe and meadow steppe, which accounted for over 98% of the total SOC storage. The spatial distribution showed a decreased trend from the meadow steppe, typical steppe to the desert steppe, corresponding to the temperature and precipitation gradient.（2） SOC changes during 1982–2012 were estimated to be 0.12 Pg C, at 7.00 g C·m–2·yr–1, which didn＇t show a significant change, indicating that SOC storage in grasslands of Inner Mongolia remained relatively stable over this period. However, topsoil organic carbon showed different trends of carbon source/sink during the past three decades. Meadow steppe and typical steppe had sequestered 0.15 and 0.03 Pg C, respectively, served as a carbon sink; while desert steppe lost 0.06 Pg C, served as a carbon source. It appears that SOC storage in grassland ecosystem may respond differently to climate change, related to vegetation type, regional climate type and grazing intensity. These results might give advice to decision makers on adopting suitable countermeasures for sustainable grassland utilization and protection.展开更多
基金Supported by the National Key Research and Development Program of China(No.2023YFC3008202)the National Natural Science Foundation of China(No.42406019)the Scientific Research Fund of Zhejiang Provincial Education Department(No.Y202353066)。
文摘The prediction of sea surface partial pressure of carbon dioxide(pCO_(2))in the South China Sea is crucial for understanding the region’s contribution to the global carbon budget and its interactions with climate change.We applied the Spatiotemporal Convolutional Long Short-Term Memory(STConvLSTM)model,integrating key environmental factors including sea surface temperature(SST),sea surface salinity(SSS),and chlorophyll a(Chl a),to predict and analyze sea surface pCO_(2)in the South China Sea.The model demonstrated high accuracy in short-term predictions(1 month),with a mean absolute error(MAE)of 0.394,a root mean square error(RMSE)of 0.659,and a coefficient of determination(R^(2))of 0.998.For long-term predictions(12 months),the model maintained its predictive capability,with an MAE of 0.667,RMSE of 1.255,and R^(2)of 0.994.Feature importance analysis revealed that sea surface pCO_(2)and SST were the main drivers of the model’s predictions,whereas Chl a and SSS had relatively minor impacts.The model’s generalization ability was further validated in the northwest Pacific Ocean and tropical Pacific Ocean,where it successfully captured the spatiotemporal variation in pCO_(2)with small prediction errors.The ST-ConvLSTM model provides an efficient and accurate tool for forecasting and analyzing sea surface pCO_(2)in the South China Sea,offering new insights into global carbon cycling and climate change.This study demonstrates the potential of deep learning in marine science and provides a significant technical support for global changes and marine ecosystem research.
基金The Public Science and Technology Research Funds Projects of Ocean of State Oceanic Administration People’s Republic of China under contract No.200905012a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions of China
文摘The global distributions of the air-sea CO2 transfer velocity and flux are retrieved from TOPEX/Poseidon and Jason altimeter data from October 1992 to December 2009 using a combined algorithm. The 17 a average global, area-weighted, Schmidt number-corrected mean gas transfer velocity is 21.26 cm/h, and the full exploration of the uncertainty of this estimate awaits further data. The average total CO2 flux （calculated by carbon） from atmosphere to ocean during the 17 a was 2.58 Pg/a. The highest transfer velocity is in the circumpolar current area, because of constant high wind speeds and currents there. This results in strong CO2 fluxes. CO2 fluxes are strong but opposite direction in the equatorial east Pacific Ocean, because the air-sea CO2 partial pressure difference is the largest in the global cceans. The results differ from the previous studies calculated using the wind speed. It is demonstrated that the air-sea transfer velocity is very important for estimating air-sea CO2 flux. It is critical to have an accurate estimation for improving calculation of CO2 flux within climate change studies.
基金financially supported by the National Natural Science Foundation of China(Nos.21875147 and 51991351)the Fundamental Research Funds for the Central Universities。
文摘Due to the important role of oil source in our life,the separation of water-in-oil emulsion is urgent and necessary.Membrane seperation technology has been an efficient and widely used method in separating oil-water separation.Herein,we report a versatile approach to fabricate surface carbonized membranes with self-standing property from biomass-derived precursor by synergistic charring of phytic acid,arginine and filter paper.The obtained membrane exhibited superhydrophobicity in oil,excellent fouling resistance,and self-supporting ability.The membrane can be cycle-used at least 12 times with high permeation flux(up to 1380 L·m^(-2)·h^(-1))and separation efficiency(up to 99.4%).
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supported by the National Basic Research Program of China (No. 2011CB605602)
文摘Polyacrylonitrile （PAN） based carbon fibers with different surface morphology were electrochemically treated in 3 wt% NH4HCO3 aqueous solution with current density up to 3.47 A/m 2 at room temperature, and surface structures, surface morphology and residual mechanical properties were characterized. The crystallite size （La） of carbon fibers would be interrupted due to excessive electrochemical etching, while the crystallite spacing （d（002）） increased as increasing current density. The disordered structures on the surface of carbon fiber with rough surface increased at the initial oxidation stage and then removed by further electrochemical etching, which resulting in continuous increase of the extent of graphitization on the fiber surface. However, the electrochemical etching was beneficial to getting ordered morphology on the surface for carbon fiber with smooth surface, especially when the current density was lower than 1.77 A/m 2 . The tensile strength and tensile modulus could be improved by 17.27% and 5.75%, respectively, and was dependent of surface morphology. The decreasing density of carbon fibers probably resulted from the volume expansion of carbon fibers caused by the abundant oxygen functional groups intercalated between the adjacent graphite layers.
基金the Institute of Particle and Science Engineering,University of Leeds and Procter & Gamble Newcastle Innovation Centre(UK) for partially funding the project
文摘Sodium carbonate and carboxymethyl cellulose powders are compressed into two-component tablets with three mass ratios,97%:3%,95%:5% and 93%:7%.The dissolution tests for two-component tablets and reference pure sodium carbonate tablets are carried out at various temperatures.The dissolution process of each tablet is measured by electrical conductivity tracking method and the concentration of dissolved sodium carbonate is quanti fied with calibrated conductivity-concentration converting equation of sodium carbonate.The quanti fied dissolution data is fitted with both surface reaction model and diffusion layer model and the results clearly show that surface reaction model is suggested as the appropriate dissolution model for all measured tablets.Therefore,it is determined that carboxymethyl cellulose is a stable element to remain the dissolution mechanism of tablet unchanged.The dissolution rate constant quanti fied with surface reaction model presents that carboxymethyl cellulose-sodium carbonate two-component tablets obtain signi ficant higher dissolution rate constant than pure sodium carbonate tablet and higher proportion of carboxymethyl cellulose leads to apparent higher dissolution rate constant.The results prove for the usage of carboxymethyl cellulose in most practical applications at a relative low-level,the effect of carboxymethyl cellulose is effective and positive for two-component tablet to enhance the dissolution process and improve dissolution rate constant and this effect is speculated coming from its dynamic physical transforming process in water including dilation and conglutination.
基金supported by the National Natural Science Foundation of China(21373048,21203027,and 21371034)
文摘Periodic density functional theory calculations have been performed to investigate the chemisorption behavior of COz molecule on a series of surface alloys that are built by dispersing individual middle-late transition metal （TM） atoms （TM = Fe, Co, Ni, Ru, Rh, Pd, Ag, Os, lr, Pt, Au） on the Cu（100） and Cu（lll） surfaces. The most stable configurations of CO2 chemisorbed on different TM/Cu surfaces are determined, and the results show that among the late transition metals, Co, Ru, and Os are potentially good dopants to enhance the chemisorption and activation of CO2 on copper surfaces. To obtain a deep understanding of the adsorption property, the bonding characteristics of the adsorption bonds are carefully examined by the crystal orbital Hamilton population technique, which reveals that the TM atom primarily provides d orbitals with z-component, namely dz2, dxz, and dvz orbitals to interact with the adsorbate.
文摘The carbon layers on implanted steel surface have been studied by means of Auger spectra. It is shown that the thickness of the carbon layer is proportional to the dose of implanted ions. By comparison with the results of friction and wear tests, the friction coefficient is smaller than 0.20 at the first part of the friction coefficient curve. It is considered that the graphitic carbon layer on the top of steel is helpful to reducing the surface friction coefficient of steel.
文摘In this letter ab initio electronic structure calculations are performed for extensive geometries Of CS2. A newly written program is used to fit the computed energies into the Sorbie-Murrel function, whose contour plots are illustrated.
基金Funded by the National Young Top Talents Plan of China(2013042)the National Science Foundation of China(21676052,21606042)+1 种基金the Science Foundation for Distinguished Young Scholars of Heilongjiang Province(JC201403)the Natural Science Foundation of Heilongjiang Province(E2015034)
文摘Surface functionalization of carbon nanofibers（CNFs） was carried out, i e, CNFs were firstly oxidized and then the surface was silanized by 3-Aminopropyltriethoxysilane（APTES） via an assembly method. A new kind of high wear resistance s-CNFs/epoxy composite was fabricated by in-situ reaction. FTIR spectroscopy was used to detect the changes of the functional groups produced by silane on the surface of CNFs. The tribological properties and microstructures of modified and unmodified CNFs/epoxy composites were studied, respectively. The expremental results indicate that APTES is covalently linked to the surface of CNFs successfully and improves the dispersion of CNF in epoxy matrix. The friction coefficients and the wear rates of s-CNFs/epoxy composites are evidently lower than those of u-CNFs/epoxy composites under the same loads. Investigations also indicate that abrasive wear is the main wear mechanism for u-CNFs/epoxy composite, with slight adhesive wear for s-CNFs/epoxy composite under the same sliding wear condition.
基金financially supported by the National Program on Key Basic Research Project of China (973 Program, No. 2012CB215405)the National Natural Science Foundation of China (No. 51174022)
文摘Carbon deposition on nickel powders in methane involves three stages in different reaction temperature ranges. Temperature programing oxidation test and Raman spectrum results indicated the formation of complex and ordered carbon structures at high deposition temperatures. The values of I（D）/I（G） of the deposited carbon reached 1.86, 1.30, and 1.22 in the first, second, and third stages, respectively. The structure of carbon in the second stage was similar to that in the third stage. Carbon deposited in the first stage rarely contained homogeneous pyrolytic deposit layers. A kinetic model was developed to analyze the carbon deposition behavior in the first stage. The rate-determining step of the first stage is supposed to be interfacial reaction. Based on the investigation of carbon deposition kinetics on nickel powders from different resources, carbon deposition rate is suggested to have a linear relation with the square of specific surface area of nickel particles.
基金supported by the third scientific survey project in Xinjiang(2022xjkk0300)the public welfare geological survey projects initiated by the China Geological Survey(DD20190296,DD20221731).
文摘Addressing global warming,a common change today,requires achieving peak carbon dioxide emissions and carbon neutrality(also referred to as the dual carbon goals).Enhancing research on the carbon cycle is urgently needed as the foundation.Water,a key carrier in the carbon cycle,necessitates investigation into groundwater carbon pools’contribution to atmospheric carbon sinks.This study assessed carbon stocks in the Yinchuan Basin’s soil and groundwater carbon pools.Findings indicate the basin’s surface soils contain approximately 24.16 Tg of organic carbon and a total of 60.01 Tg of carbon.In contrast,the basin’s groundwater holds around 4.90 Tg of carbon,roughly one-fifth of the organic carbon in surface soils.Thus,groundwater and soil carbon pools possess comparable carbon stocks,underscoring the importance of the groundwater carbon pool.Studies on terrestrial carbon balance should incorporate groundwater carbon pools,which deserve increased focus.Evaluating groundwater carbon pools’contributions is vital for achieving the dual carbon goals.
基金supported by the Natural Science Foundation of China(NSFC Grant No.20803064)the Natural Science Foundation of Zhejiang Provence(Y4090348 and LY12B03007)Qianjiang Talent Project in Zhejiang Province(2010R10039 and 2013R10056)
文摘A series of high surface area graphitic carbon materials （HSGCs） were prepared by ball-milling method. Effect of the graphitic degree of HSGCs on the catalytic performance of Ba-Ru-K/HSGC-x （x is the ball-milling time in hour） catalysts was studied using ammonia synthesis as a probe reaction. The graphitic degree and pore structure of HSGC-x supports could be successfully tuned via the variation of ball-milling time. Ru nanoparticles of different Ba-Ru-K/HSGC-x catalysts are homogeneously distributed on the supports with the particle sizes ranging from 1.6 to 2.0 nm. The graphitic degree of the support is closely related to its facile electron transfer capability and so plays an important role in improving the intrinsic catalytic performance of Ba-Ru-K/HSGC-x catalyst.
基金the Natural Science Foundation of China(21922803,92034301,22008066,and 21776077)the China Postdoctoral Science Foundation(BX20190116)+1 种基金the Innovation Program of Shanghai Municipal Education Commission,the Program of Shanghai Academic/Tech-nology Research Leader(21XD1421000)111 Project of the Min-istry of Education of China(B08021)。
文摘Taming the electron transfer across metal–support interfaces appears to be an attractive yet challenging methodology to boost catalytic properties.Herein,we demonstrate a precise engineering strategy for the carbon surface chemistry of Pt/C catalysts—that is,for the electron-withdrawing/donating oxygencontaining groups on the carbon surface—to fine-tune the electrons of the supported metal nanoparticles.Taking the ammonia borane hydrolysis as an example,a combination of density functional theory(DFT)calculations,advanced characterizations,and kinetics and isotopic analyses reveals quantifiable relationships among the carbon surface chemistry,Pt charge state and binding energy,activation entropy/enthalpy,and resultant catalytic activity.After decoupling the influences of other factors,the Pt charge is unprecedentedly identified as an experimentally measurable descriptor of the Pt active site,contributing to a 15-fold increment in the hydrogen generation rate.Further incorporating the Pt charge with the number of Pt active sites,a mesokinetics model is proposed for the first time that can individually quantify the contributions of the electronic and geometric properties to precisely predict the catalytic performance.Our results demonstrate a potentially groundbreaking methodology to design and manipulate metal–carbon catalysts with desirable properties.
基金the financial support by the Special Fund for Basic Scientific Research of Central Colleges (No.2009KH10)the Beijing Postdoctoral Fund (No. B148)the Green Shoots Plan of Beijing Academy of Science and Technology of China (No. B142)
文摘A series of activated carbons from Taixi anthracite were prepared by steam activation in the presence of KOH and then they were modified by different methods. The regulation of porosity and the modification of surface chemistry were carried out with the aim to improve the benzene adsorption capacity of activated carbon. The influences of KOH and activation process parameters including activation temperature, activation time and steam flow rate on porosity of activated carbon were evaluated, and the effect of modification methods on surface chemistry was investigated. Also, the relationship between benzene adsorption capacity and porosity and surface chemistry was analyzed. Results show that activation temperature is the dominant factor in the activation process; the introduction of KOH into the raw material can enhance the reactivity of char in activation process, meanwhile it shows a negative effect on the porosity development, especially on the mesopore development. Results of FTIR analysis indicate that anthracite-based activated carbon with condensed aromatics and chemically inert oxygen does not present the nature to be surface modified. Besides, benzene adsorption capacity has an approximate linear relationship with surface area and in our preparation, benzene adsorption capacity and surface area of activated carbon are up to 1210 m 2 /g and 423 mg/g, respectively.
基金National Science Foundation of China(No.21173167)the Science and Technology Committee of Shaanxi Province(Grant No.2014KW09-03)+1 种基金Program for New Century Excellent Talents in University(NCET-13-0953)the Research Fund of the State Key Lab of Solidification Processing(NWPU),China(Grant No.15-BZ-2015)
文摘Facile production of high quality activated carbons from biomass materials has greatly triggered much attention presently. In this paper, a series of interconnected porous carbon materials from lotus root shells biomass are prepared via simple pyrolysis and followed by a KOH activation process. The prepared carbons exhibit high specific surface areas of up to 2961 m^2/g and large pore volume～1.47 cm3/g. In addition, the resultant porous carbons served as electrode materials in supercapacitor exhibit high specific capacitance and outstanding recycling stability and high energy density. In particular, their specific capacitance retention was almost 100% after 10500 cycles at a current density of 2 A/g. Remarkabely, the impact of the tailored specific surface areas of various carbon samples on their capacitive performances is systematically investigated.Generally, it was believed that the highly-developed porosity features（including surface areas and pore volume and pore size-distributions）, together with the good conductivity of activated carbon species, play a key role in effectively improving the storage energy performances of the porous carbon electrode materials in supercapacitor.
基金supported by a research fund of Chungnam National University in 2014
文摘Herein, we report a simple and effective preparation of ultrafine CNFs （u-CNFs） with high surface area via electrospinning of two immiscible polymers [polyacrylonitrile （PAN） and poly（methyl methacry- late） （PMMA）] followed by calcination at high temperature in an inert atmosphere. Various electrospinning conditions were optimized in detail. Four different kinds of PAN/PMMA ratios （10/0, 7：3, 5：5 and 3：7） were chosen and found that the PAN/PMMA ratio of 3：7 （PAN/PMMA-3：7） is the optimum one. BET anal- ysis showed the specific surface area of the u-CNFs-3：7 was 46Z57 m2/g with an excellent pore volume （1.15 cms g-l） and an average pore size （9.48 nm）： it is about 25 times higher than the conventional CNFs （c-CNFs）. TEM and FE-SEM images confirmed the ultrafine structure of the CNFs with a thinner fiber di- ameter of-50 nm. The graphitic nature and atomic arrangement of the u-CNFs were investigated by Raman and XPS analyses. For the supercapacitor application, unlike the common electrode preparation methods, the u-CNFs-3：7 was used without any activation, chemical or mechanical modifications. The u-CNFs- 3：7 showed a better specific capacitance of 86 Fig in 1 mol/L 1-12S04 when compared to pure CNFs. The excellent physicochemical properties make the u-CNFs-3：7 an alternative choice to the existing CNFs for the supercapacitors.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51172180 and 51372200)the Scientific Research Plan Project of Shaanxi Education Department (Grant No. 16JK1551)+1 种基金the Science and Technology Plan of Xi’an (Grant No. CXY1430(9))the China Postdoctoral Science Foundation Funded Project (Grant No. 2016M592824)
文摘Multi-walled carbon nanotubes（CNTs） were modified by an amination treatment with hexamethylenediamine（HMD）, and then bismaleimide（BMI）/epoxy（E-44）/CNTs ternary composites were prepared using modified CNTs as the reinforcement via a simple mixing and curing molding method. The results show that the surfaces of CNTs are grafted polymer with the thickness of 3 nm and the dispersity of surface grafted carbon nanotubes（SG-CNTs） in the resin composites can be improved. The prepared composites contain C-C, C-N, C=O and-COOH groups and can keep a smooth surface. In addition, the composites have the flexural strength of 152 MPa, the tensile strength of 73 MPa and the impact strength of 87 k J m^（-2）,respectively, when the weight ratio of BMI to E-44 is 1：8 and the content of SG-CNTs is 2 wt%. However,the thermal stability of the composites with SG-CNTs is a little lower than that of the composites without SG-CNTs.
基金The National Basic Research Program of China(973 Program),No.2011CB403206No.2012CB416906National Key Technology R&D Program,No.2013BAC03B04
文摘Soil carbon sequestration and potential has been a focal issue in global carbon research. Under the background of global change, the estimation of the size as well as its change of soil organic carbon（SOC） storage is of great importance. Based on soil data from the second national soil survey and field survey during 2011–2012, by using the regression method between sampling soil data and remote sensing data, this paper aimed to investigate spatial distribution and changes of topsoil（0–20 cm） organic carbon storage in grasslands of Inner Mongolia between the 1980 s and 2010 s. The results showed that：（1） the SOC storage in grasslands of Inner Mongolia between the 1980 s and 2010 s was estimated to be 2.05 and 2.17 Pg C, with an average density of 3.48 and 3.69 kg C·m–2, respectively. The SOC storage was mainly distributed in the typical steppe and meadow steppe, which accounted for over 98% of the total SOC storage. The spatial distribution showed a decreased trend from the meadow steppe, typical steppe to the desert steppe, corresponding to the temperature and precipitation gradient.（2） SOC changes during 1982–2012 were estimated to be 0.12 Pg C, at 7.00 g C·m–2·yr–1, which didn＇t show a significant change, indicating that SOC storage in grasslands of Inner Mongolia remained relatively stable over this period. However, topsoil organic carbon showed different trends of carbon source/sink during the past three decades. Meadow steppe and typical steppe had sequestered 0.15 and 0.03 Pg C, respectively, served as a carbon sink; while desert steppe lost 0.06 Pg C, served as a carbon source. It appears that SOC storage in grassland ecosystem may respond differently to climate change, related to vegetation type, regional climate type and grazing intensity. These results might give advice to decision makers on adopting suitable countermeasures for sustainable grassland utilization and protection.
