China’s low-carbon development path will make significant contributions to achieving global sustainable development goals.Due to the diverse natural and economic conditions across different regions in China,there exi...China’s low-carbon development path will make significant contributions to achieving global sustainable development goals.Due to the diverse natural and economic conditions across different regions in China,there exists an imbalance in the distribution of car-bon emissions.Therefore,regional cooperation serves as an effective means to attain low-carbon development.This study examined the pattern of carbon emissions and proposed a potential joint emission reduction strategy by utilizing the industrial carbon emission intens-ity(ICEI)as a crucial factor.We utilized social network analysis and Local Indicators of Spatial Association(LISA)space-time trans-ition matrix to investigate the spatiotemporal connections and discrepancies of ICEI in the cities of the Pearl River Basin(PRB),China from 2010 to 2020.The primary drivers of the ICEI were determined through geographical detectors and multi-scale geographically weighted regression.The results were as follows:1)the overall ICEI in the Pearl River Basin is showing a downward trend,and there is a significant spatial imbalance.2)There are numerous network connections between cities regarding the ICEI,but the network structure is relatively fragile and unstable.3)Economically developed cities such as Guangzhou,Foshan,and Dongguan are in the center of the network while playing an intermediary role.4)Energy consumption,industrialization,per capita GDP,urbanization,science and techno-logy,and productivity are found to be the most influential variables in the spatial differentiation of ICEI,and their combination in-creased the explanatory power of the geographic variation of ICEI.Finally,through the analysis of differences and connections in urban carbon emissions under different economic levels and ICEI,the study suggests joint carbon reduction strategies,which are centered on carbon transfer,financial support,and technological assistance among cities.展开更多
A novel process was proposed for the utilization of potash feldspar by roasting in the presence of sodium carbonate.The effects of roasting temperature,granularity,molar ratio of sodium carbonate to potash feldspar an...A novel process was proposed for the utilization of potash feldspar by roasting in the presence of sodium carbonate.The effects of roasting temperature,granularity,molar ratio of sodium carbonate to potash feldspar and roasting time on the silica extraction rate were investigated.Under the optimal roasting conditions,the silica extraction rate was 98%.The optimal conditions,determined using an orthogonal experiment,were found to be roasting temperature of 875 °C,potash feldspar granularity of 74– 89 μm,molar ratio of sodium carbonate to potash feldspar of 1.2:1,and roasting time of 80 min.The kinetics of potash feldspar roasting in the presence of sodium carbonate was described by the shrinking core model and the reaction rate was found to be controlled by the chemical reaction at the particle surface.According to the Arrhenius expression,the activation energy was 164.99 k J/mol,and the process could be expressed as [1-(1-α)1/3]=2.66×105 exp[-164990/(RT)] t.展开更多
The carbothermic reduction of vanadium titanomagnetite concentrate(VTC)with the assistance of Na_(2)CO_(3)was conducted in an argon atmosphere between 1073 and 1473 K.X-ray diffraction and scanning electron microscopy...The carbothermic reduction of vanadium titanomagnetite concentrate(VTC)with the assistance of Na_(2)CO_(3)was conducted in an argon atmosphere between 1073 and 1473 K.X-ray diffraction and scanning electron microscopy were used to investigate the phase transformations during the reaction.By investigating the reaction between VTC and Na_(2)CO_(3),it was concluded that molten Na_(2)CO_(3)broke the structure of titanomagnetite by combining with the acidic oxides(Fe_(2)O_(3),TiO_(2),Al_(2)O_(3),and SiO_(2))to form a Na-rich melt and release FeO and MgO.Therefore,Na_(2)CO_(3)accelerated the reduction rate.In addition,adding Na_(2)CO_(3)also benefited the agglomeration of iron particles and the slag–metal separation by decreasing the viscosity of the slag.Thus,Na_(2)CO_(3)assisted carbothermic reduction is a promising method for treating VTC at low temperatures.展开更多
The kinetics and mechanism of natural wolframite interactions with sodium carbonate during air heating were studied.X-ray phase and X-ray microanalysis were used to establish that the initial monocrystalline wolframit...The kinetics and mechanism of natural wolframite interactions with sodium carbonate during air heating were studied.X-ray phase and X-ray microanalysis were used to establish that the initial monocrystalline wolframite consists of Fe0.5 Mn0.5 WO4 and Fe0.3 Mn0.7 WO4.Differential thermal analysis showed that the interaction of wolframite with sodium carbonate begins above 450°C with the formation of tungstate,sodium ferrite,iron oxides,and manganese.Model experiments on sintering with the subsequent removal of water-soluble compounds(leaching)tracked the change in the structure of wolframite.The atomic ratio of Fe/Mn in wolframite does not change up to 600°C,and subsequently decreases to 0.2 during heating,which allows the mechanism of the process to be identified and indicates the greater reactivity of wolframites with an increased proportion of iron.Thermal analysis with data processing using non-isothermal kinetics established that the interaction of wolframite with sodium carbonate in an air stream proceeds via a two-stage mechanism,wherein the first stage is limited by diffusion(activation energy,E=243 kJ/mol)and the second stage is limited by autocatalysis(activation energy,E=212 k J/mol)due to the formation of a Na2 WO4–Na2 CO3 eutectic.展开更多
Hollow calcium carbonate(CaCO3) microspheres were prepared in aqueous solution with the presence of polyoxyethylene(20) sorbitan monolaurate(Tween20) and sodium dodecyl sulfate(SDS).The microspheres were characterized...Hollow calcium carbonate(CaCO3) microspheres were prepared in aqueous solution with the presence of polyoxyethylene(20) sorbitan monolaurate(Tween20) and sodium dodecyl sulfate(SDS).The microspheres were characterized with X-ray diffraction(XRD),scanning electron microscopy(SEM) and transmission electron microscope(TEM).The X-ray diffraction data showed that the hollow CaCO3 microsphere consisted of calcite crystals.The influence of Tween20 and SDS concentrations on the morphology of CaCO3 crystals was investigated.The results suggested that the"core-shell model"of Tween20/SDS micelle aggregated as templates,which could control the growth of hollow CaCO3 microspheres.The interaction between mixed surfactants and calcium ions played a critical role in organizing calcium carbonate in microscopic level.展开更多
The objective of this study is to present a simple method of statistical calculation that allowed us to determine the relationship between the different data obtained from the characterization of the synthetic carbona...The objective of this study is to present a simple method of statistical calculation that allowed us to determine the relationship between the different data obtained from the characterization of the synthetic carbonated apatites containing sodium, in order to find the fundamental substitution mechanism(s) for incorporation of Na+ and?CO32- and to establish the general formula. For that, a series of hydroxyapatites containing carbonate and sodium (Na-CO3HAps) has been obtained by the precipitation method. All the compounds were characterized by infrared spectra (IR), powder X-ray diffraction (PXRD) and elemental analysis. The statistical treatment of the experiment result allows us to determine the relationship between one variable and the change in the other and to found the fundamental substitution mechanism(s) for incorporation of Na+ and?CO32- . Analysis of variance (ANOVA) allows us to test the models proposed.展开更多
The detailed kinetic model of selective non-catalytic reduction(SNCR)of nitric oxide,including so- dium species reactions,was developed on the basis of recent studies on thermal DeNOx mechanism,NOxOUT mechanism and pr...The detailed kinetic model of selective non-catalytic reduction(SNCR)of nitric oxide,including so- dium species reactions,was developed on the basis of recent studies on thermal DeNOx mechanism,NOxOUT mechanism and promotion mechanism of Na2CO3.The model was validated by comparison with several experi- mental findings,thus providing an effective tool for the primary and promoted SNCR process simulation.Experi- mental and simulated results show part-per-million level of sodium carbonate enhances NO removal efficiency and extend the effective SNCR temperature range in comparison with use of a nitrogen agent alone.The kinetic model- ing,sensitivity and rate-of-production analysis suggest that the performance improvement can be explained as ho- mogeneous sodium species reactions producing more reactive OH radicals.The net result of sodium species reac- tions is conversion of H2O and inactive HO2 radicals into reactive OH radicals,i.e.H2O+HO2=3OH,which en- hances the SNCR performance of nitrogen agents by mainly increasing the production rate of NH2 radicals.More- over,N2O and CO are eliminated diversely via the reactions Na+N2O=NaO+N2,NaO+CO=Na+CO2 and NaO2+CO=NaO+CO2,in the promoted SNCR process,especially in the NOxOUT process.展开更多
The technology of direct reduction by adding sodium carbonate (Na2CO3 ) and magnetic separation was developed to treat Western Australian high phosphorus iron ore. The iron ore and reduced product were investigated by...The technology of direct reduction by adding sodium carbonate (Na2CO3 ) and magnetic separation was developed to treat Western Australian high phosphorus iron ore. The iron ore and reduced product were investigated by optical microscopy and scanning electron microscopy. It is found that phosphorus exists within limonite in the form of solid solution, which cannot be removed through traditional ways. During reduction roasting, Na2CO3 reacts with gangue minerals (SiO2 and Al2O3 ), forming aluminum silicate-containing phosphorus and damaging the ore structure, which promotes the separation between iron and phosphorus during magnetic separation. Meanwhile, Na2CO3 also improves the growth of iron grains, increasing the iron grade and iron recovery. The iron concentrate, assaying 94.12wt% Fe and 0.07wt% P at the iron recovery of 96.83% and the dephosphorization rate of 74.08%, is obtained under the optimum conditions. The final product (metal iron powder) after briquetting can be used as the burden for steelmaking by an electric arc furnace to replace scrap steel.展开更多
The effects of carbonate minerals(dolomite and siderite) on the flotation of hematite using sodium oleate as a collector were investigated through flotation tests, supplemented by dissolution measurements, solution ch...The effects of carbonate minerals(dolomite and siderite) on the flotation of hematite using sodium oleate as a collector were investigated through flotation tests, supplemented by dissolution measurements, solution chemistry calculations, zeta-potential measurements, Fourier transform infrared(FTIR) spectroscopic studies, and X-ray photoelectron spectroscopy(XPS) analyses. The results of flotation tests show that the presence of siderite or dolomite reduced the recovery of hematite and that the inhibiting effects of dolomite were stronger. Dissolution measurements, solution chemistry calculations, and flotation tests confirmed that both the cations(Ca^(2+) and Mg^(2+)) and CO_3^(2+)ions dissolved from dolomite depressed hematite flotation, whereas only the 23CO-ions dissolved from siderite were responsible for hematite depression. The zeta-potential, FTIR spectroscopic, and XPS analyses indicated that Ca^(2+), Mg^(2+), and CO_3^(2-)(HCO_3^-) could adsorb onto the hematite surface, thereby hindering the adsorption of sodium oleate, which was the main reason for the inhibiting effects of carbonate minerals on hematite flotation.展开更多
According to the principle of mass balances and thermodynamic data, lg [Me]—pH diagrams (Me=Ca, Mo) for Ca-Mo-CO3-H2O system at 25 ℃ were presented with total dissolved carbon-containing ions concentrations of 0.01 ...According to the principle of mass balances and thermodynamic data, lg [Me]—pH diagrams (Me=Ca, Mo) for Ca-Mo-CO3-H2O system at 25 ℃ were presented with total dissolved carbon-containing ions concentrations of 0.01 mol/L and 1 mol/L, and lg [Me]—pH diagram for Ca-Mo-H2O system at 25 ℃ was also depicted. The effects of system pH value and total dissolved carbon-containing ions concentrations on the concentrations of the species in Ca-Mo-CO3-H2O system were studied. The results show that the stability region of CaMoO4 reduces significantly in the presence of sodium carbonate. In order to achieve effective leaching of molybdenum from CaMoO4, a certain concentration of sodium carbonate is necessary. High total dissolved carbon-containing ions concentrations and high pH values facilitate to the leaching of CaMoO4 and dissolved sodium carbonate is an efficient leaching agent for decomposing CaMoO4.展开更多
Heterogeneous photocatalysed reduction of aqueous Na2CO3 was carried out by using nano LaCoO3 semiconductor powders. Formic acid and formaldehyde were identified as photoproducts,and were measured spectrophotometrical...Heterogeneous photocatalysed reduction of aqueous Na2CO3 was carried out by using nano LaCoO3 semiconductor powders. Formic acid and formaldehyde were identified as photoproducts,and were measured spectrophotometrically using Nash reagent. The effect of different parameters such as sodium carbonate concentration,amount of photocatalyst and different light sources on the yield of photoproducts was also investigated. It shows that nano LaCoO3 has photocatalytic activity. Irradiation leads to the production of electrons in the conduction band of the LaCoO3 semiconductor. It is likely that the photoproduced electrons initially reduce CO3 （2-） to HCOO -,and then to HCHO and CH3OH.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
Dissolution kinetics of sodium carbonate is investigated with the image analysis method at the approach of single particle.The dissolution experiments are carried out in an aqueous solution under a series of controlle...Dissolution kinetics of sodium carbonate is investigated with the image analysis method at the approach of single particle.The dissolution experiments are carried out in an aqueous solution under a series of controlled temperature and p H.The selected sodium carbonate particles are all spherical with the same mass and diameter.The dissolution process is quantified with the measurement of particle diameter from dissolution images.The concentration of dissolved sodium carbonate in solvent is calculated with the measured diameter of particle.Both surface reaction model and mass transport model are implemented to determine the dissolution mechanism and quantify the dissolution rate constant at each experimental condition.According to the fitting results with both two models,it is clarified that the dissolution process at the increasing temperature is controlled by the mass transport of dissolved sodium carbonate travelling from particle surface into solvent.The dissolution process at the increasing pH is controlled by the chemical reaction on particle surface.Furthermore,the dissolution rate constant for each single spherical sodium carbonate particle is quantified and the results show that the dissolution rate constant of single spherical sodium carbonate increases significantly with the rising of temperature,but decreases with the increasing of pH conversely.展开更多
Room-temperature sodium–sulfur(RT/Na–S)batteries are regarded as promising large-scale stationary energy storage systems owing to their high energy density and low cost as well as the earth-abundant reserves of sodi...Room-temperature sodium–sulfur(RT/Na–S)batteries are regarded as promising large-scale stationary energy storage systems owing to their high energy density and low cost as well as the earth-abundant reserves of sodium and sulfur.However,the diffusion of polysulfides and sluggish kinetics of conversion reactions are still major challenges for their application.Herein,we developed a powerful and functional separator to inhibit the shuttle effect by coating a lightweight three-dimensional cellulose nanofiber-derived carbon aerogel on a glass fiber separator(denoted NSCA@GF).The hierarchical porous structures,favorable electronic conductivity,and three-dimensional interconnected network of N,S-codoped carbon aerogel endow a multifunctional separator with strong polysulfide anchoring capability and fast reaction kinetics of polysulfide conversion,which can act as the barrier layer and an expanded current collector to increase sulfur utilization.Moreover,the hetero-doped N/S sites are believed to strengthen polysulfide anchoring capability via chemisorption and accelerate the redox kinetics of polysulfide conversion,which is confirmed from experimental and theoretical results.As a result,the assembled Na–S coin cells with the NSCA@GF separator showed a high reversible capacity(788.8 mAh g^(−1) at 0.1 C after 100 cycles)and superior cycling stability(only 0.059%capacity decay per cycle over 1000 cycles at 1 C),thereby demonstrating the significant potential for application in high-performance RT/Na–S batteries.展开更多
The Hashemite Kingdom of Jordan has a large reserve of raw Bentonite in the area of Ain Al-Baida at Basin of Al-Azraq city that has not activated yet to become valid as drilling mud. The Ore Ain AL-Baida Bentonite was...The Hashemite Kingdom of Jordan has a large reserve of raw Bentonite in the area of Ain Al-Baida at Basin of Al-Azraq city that has not activated yet to become valid as drilling mud. The Ore Ain AL-Baida Bentonite was investigated and activated by Na2CO3. The products were investigated by chemical analysis, X-Ray Diffraction, rheological properties and free swelling index with clay fraction. It was observed that the activities clay ranged between 0.98 < AC < 1.48 medium to high content of clay minerals. In addition, it was determined the Atterberg limits, the results of plasticity chart and relation between index and clay fraction. This means that the amount of the attracted water will be suitable influenced by the clay that is present in Ore Ain Al-Baida bentonite. The liquid limit was ranged between 83% to 140%, and plastic limit ranged between 39% - 48%. Also, rheological properties (apparent viscosity, plastic viscosity), gel strength, yield point, filtrate loss. These properties have been compared with those standard specifications properties required for the drilling fluid in order to know the appropriate circumstances to activate the Bentonite ore of Ain Al Baida at Azraq basin to become close to the standard specifications required for the drilling fluids, the ratio between Y.P/P.V was ranged 0.88 to 1.21, it is meant that the behavior of drilling fluids confirms the Bingham plastic and power-law rheological models using fine grinding of bentonite mixture with 3% - 6% concentration of sodium carbonate powder.展开更多
This paper tried to develop the optimum procedure for microencapsulating water soluble solid powder with the thermal responsible material by the melting dispersion cooling method. Sodium hydrogen carbonate was adopted...This paper tried to develop the optimum procedure for microencapsulating water soluble solid powder with the thermal responsible material by the melting dispersion cooling method. Sodium hydrogen carbonate was adopted as a water soluble solid powder instead of microencapsulating carbon dioxide gas. The shell material was composed of olefin wax and α-tocopherol. In the experiment, the concentration of oil soluble surfactant and the water soluble surfactant species were changed. Sodium hydrogen carbonate was treated in the aqueous solution dissolving the water soluble surfactant to form the finer sodium hydrogen carbonate powder and to increase the content. The microencapsulation efficiency could be increased with the concentration of oil soluble surfactant and considerably increased by treating sodium hydrogen carbonate with the water soluble surfactant. Sodium hydrogen carbonate was protected well from environmental water. The microcapsules showed the thermal responsibility to generate carbon dioxide.展开更多
Heterogenous photocatalyzed reduction of aqueous Na2CO3 has been carried out by using nano SrFeO3 semiconductor powders. Formic acid, formaldehyde and methyl alcohol were identified as photoproducts, and were measured...Heterogenous photocatalyzed reduction of aqueous Na2CO3 has been carried out by using nano SrFeO3 semiconductor powders. Formic acid, formaldehyde and methyl alcohol were identified as photoproducts, and were measured spectrophotometrically. The effect of the variation of different parameters such as sodium carbonate concentration, amount of photocatalyst and different light sources on the yield of photoproducts was also investigated. It shows that nano SrFeO3 has photocatalytic activity. Irradiation leads to the production of electrons in the conduction band of the SrFeO3 semiconductor. It is likely that the photoproduced electrons reduce CO32- initially to HCOO-, and then to HCHO and CH3OH.展开更多
A novel process was developed for the preparation of ultrafine silica from potash feldspar. In the first step, potash feldspar was roasted with Na_2CO_3 and was followed by leaching using Na OH solution to increase th...A novel process was developed for the preparation of ultrafine silica from potash feldspar. In the first step, potash feldspar was roasted with Na_2CO_3 and was followed by leaching using Na OH solution to increase the levels of potassium, sodium, and aluminum in the solid residue. The leaching solution was then carbonated to yield ultrafine silica. The optimized reaction conditions in the roasting process were as follows: an Na_2CO_3-to-potash feldspar molar ratio of 1.1, a reaction temperature of 875°C, and a reaction time of 1.5 h. Under these conditions, the extraction rate of SiO_2 was 98.13%. The optimized carbonation conditions included a final solution p H value of 9.0, a temperature of 40°C, a CO_2 flow rate of 6 m L/min, a stirring intensity of 600 r/min, and an ethanol-to-water volume ratio of 1:9. The precipitation rate and granularity of the SiO_2 particles were 99.63% and 200 nm, respectively. We confirmed the quality of the obtained ultrafine silica by comparing the recorded indexes with those specified in Chinese National Standard GB 25576―2010.展开更多
Soddium carbonate peroxider is a compound of hydrogen peroxide and sodium carbonate. Thanks to its effectiveness in laundry, bleaching and disinfecting, sodium carbonate peroxider is very popular on the market, and is...Soddium carbonate peroxider is a compound of hydrogen peroxide and sodium carbonate. Thanks to its effectiveness in laundry, bleaching and disinfecting, sodium carbonate peroxider is very popular on the market, and is used as a contrast colour in producing reductive pigments, and as a disinfectant展开更多
基金Under the auspices of the Philosophy and Social Science Planning Project of Guizhou,China(No.21GZZD59)。
文摘China’s low-carbon development path will make significant contributions to achieving global sustainable development goals.Due to the diverse natural and economic conditions across different regions in China,there exists an imbalance in the distribution of car-bon emissions.Therefore,regional cooperation serves as an effective means to attain low-carbon development.This study examined the pattern of carbon emissions and proposed a potential joint emission reduction strategy by utilizing the industrial carbon emission intens-ity(ICEI)as a crucial factor.We utilized social network analysis and Local Indicators of Spatial Association(LISA)space-time trans-ition matrix to investigate the spatiotemporal connections and discrepancies of ICEI in the cities of the Pearl River Basin(PRB),China from 2010 to 2020.The primary drivers of the ICEI were determined through geographical detectors and multi-scale geographically weighted regression.The results were as follows:1)the overall ICEI in the Pearl River Basin is showing a downward trend,and there is a significant spatial imbalance.2)There are numerous network connections between cities regarding the ICEI,but the network structure is relatively fragile and unstable.3)Economically developed cities such as Guangzhou,Foshan,and Dongguan are in the center of the network while playing an intermediary role.4)Energy consumption,industrialization,per capita GDP,urbanization,science and techno-logy,and productivity are found to be the most influential variables in the spatial differentiation of ICEI,and their combination in-creased the explanatory power of the geographic variation of ICEI.Finally,through the analysis of differences and connections in urban carbon emissions under different economic levels and ICEI,the study suggests joint carbon reduction strategies,which are centered on carbon transfer,financial support,and technological assistance among cities.
基金Project(51204054)supported by the National Natural Science Foundation of ChinaProject(2007CB613603)supported by the National Basic Research Program of ChinaProject(N140204011)supported by the Ministry of Education Basic Scientific Research Business Expenses,China
文摘A novel process was proposed for the utilization of potash feldspar by roasting in the presence of sodium carbonate.The effects of roasting temperature,granularity,molar ratio of sodium carbonate to potash feldspar and roasting time on the silica extraction rate were investigated.Under the optimal roasting conditions,the silica extraction rate was 98%.The optimal conditions,determined using an orthogonal experiment,were found to be roasting temperature of 875 °C,potash feldspar granularity of 74– 89 μm,molar ratio of sodium carbonate to potash feldspar of 1.2:1,and roasting time of 80 min.The kinetics of potash feldspar roasting in the presence of sodium carbonate was described by the shrinking core model and the reaction rate was found to be controlled by the chemical reaction at the particle surface.According to the Arrhenius expression,the activation energy was 164.99 k J/mol,and the process could be expressed as [1-(1-α)1/3]=2.66×105 exp[-164990/(RT)] t.
基金financially supported by the National Key R&D Program of China(No.2018YFC1900500)the National Natural Science Foundation of China(Nos.21908231,51774260,51804289,and 51904286)+2 种基金the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences(No.QYZDJ-SSW-JSC021)the CAS Interdisciplinary Innovation Teamthe Special Project for Transformation of Major Technological Achievements in Hebei Province,China(No.19044012Z)。
文摘The carbothermic reduction of vanadium titanomagnetite concentrate(VTC)with the assistance of Na_(2)CO_(3)was conducted in an argon atmosphere between 1073 and 1473 K.X-ray diffraction and scanning electron microscopy were used to investigate the phase transformations during the reaction.By investigating the reaction between VTC and Na_(2)CO_(3),it was concluded that molten Na_(2)CO_(3)broke the structure of titanomagnetite by combining with the acidic oxides(Fe_(2)O_(3),TiO_(2),Al_(2)O_(3),and SiO_(2))to form a Na-rich melt and release FeO and MgO.Therefore,Na_(2)CO_(3)accelerated the reduction rate.In addition,adding Na_(2)CO_(3)also benefited the agglomeration of iron particles and the slag–metal separation by decreasing the viscosity of the slag.Thus,Na_(2)CO_(3)assisted carbothermic reduction is a promising method for treating VTC at low temperatures.
基金Basic Research of the Ural Branch of the Russian Academy of Sciences (No. AAAA-A18-118012590113-6) using equipment of Collaborative usage centre “Ural-M”
文摘The kinetics and mechanism of natural wolframite interactions with sodium carbonate during air heating were studied.X-ray phase and X-ray microanalysis were used to establish that the initial monocrystalline wolframite consists of Fe0.5 Mn0.5 WO4 and Fe0.3 Mn0.7 WO4.Differential thermal analysis showed that the interaction of wolframite with sodium carbonate begins above 450°C with the formation of tungstate,sodium ferrite,iron oxides,and manganese.Model experiments on sintering with the subsequent removal of water-soluble compounds(leaching)tracked the change in the structure of wolframite.The atomic ratio of Fe/Mn in wolframite does not change up to 600°C,and subsequently decreases to 0.2 during heating,which allows the mechanism of the process to be identified and indicates the greater reactivity of wolframites with an increased proportion of iron.Thermal analysis with data processing using non-isothermal kinetics established that the interaction of wolframite with sodium carbonate in an air stream proceeds via a two-stage mechanism,wherein the first stage is limited by diffusion(activation energy,E=243 kJ/mol)and the second stage is limited by autocatalysis(activation energy,E=212 k J/mol)due to the formation of a Na2 WO4–Na2 CO3 eutectic.
基金Supported by the Beijing Natural Science Foundation(2082021)the National Science & Technology Pillar Program in the 12th Five-Year Plan Period (2011BAE06B06-2)
文摘Hollow calcium carbonate(CaCO3) microspheres were prepared in aqueous solution with the presence of polyoxyethylene(20) sorbitan monolaurate(Tween20) and sodium dodecyl sulfate(SDS).The microspheres were characterized with X-ray diffraction(XRD),scanning electron microscopy(SEM) and transmission electron microscope(TEM).The X-ray diffraction data showed that the hollow CaCO3 microsphere consisted of calcite crystals.The influence of Tween20 and SDS concentrations on the morphology of CaCO3 crystals was investigated.The results suggested that the"core-shell model"of Tween20/SDS micelle aggregated as templates,which could control the growth of hollow CaCO3 microspheres.The interaction between mixed surfactants and calcium ions played a critical role in organizing calcium carbonate in microscopic level.
文摘The objective of this study is to present a simple method of statistical calculation that allowed us to determine the relationship between the different data obtained from the characterization of the synthetic carbonated apatites containing sodium, in order to find the fundamental substitution mechanism(s) for incorporation of Na+ and?CO32- and to establish the general formula. For that, a series of hydroxyapatites containing carbonate and sodium (Na-CO3HAps) has been obtained by the precipitation method. All the compounds were characterized by infrared spectra (IR), powder X-ray diffraction (PXRD) and elemental analysis. The statistical treatment of the experiment result allows us to determine the relationship between one variable and the change in the other and to found the fundamental substitution mechanism(s) for incorporation of Na+ and?CO32- . Analysis of variance (ANOVA) allows us to test the models proposed.
基金Supported by the Natural Science Foundation of Shandong Province （No.Z2006F04） and Science and Technology Program for Environment Protection of Shandong Province （No.2006046）.
文摘The detailed kinetic model of selective non-catalytic reduction(SNCR)of nitric oxide,including so- dium species reactions,was developed on the basis of recent studies on thermal DeNOx mechanism,NOxOUT mechanism and promotion mechanism of Na2CO3.The model was validated by comparison with several experi- mental findings,thus providing an effective tool for the primary and promoted SNCR process simulation.Experi- mental and simulated results show part-per-million level of sodium carbonate enhances NO removal efficiency and extend the effective SNCR temperature range in comparison with use of a nitrogen agent alone.The kinetic model- ing,sensitivity and rate-of-production analysis suggest that the performance improvement can be explained as ho- mogeneous sodium species reactions producing more reactive OH radicals.The net result of sodium species reac- tions is conversion of H2O and inactive HO2 radicals into reactive OH radicals,i.e.H2O+HO2=3OH,which en- hances the SNCR performance of nitrogen agents by mainly increasing the production rate of NH2 radicals.More- over,N2O and CO are eliminated diversely via the reactions Na+N2O=NaO+N2,NaO+CO=Na+CO2 and NaO2+CO=NaO+CO2,in the promoted SNCR process,especially in the NOxOUT process.
基金support by China Scholarship Council(No.201206370127)support from CSIRO,Australia
文摘The technology of direct reduction by adding sodium carbonate (Na2CO3 ) and magnetic separation was developed to treat Western Australian high phosphorus iron ore. The iron ore and reduced product were investigated by optical microscopy and scanning electron microscopy. It is found that phosphorus exists within limonite in the form of solid solution, which cannot be removed through traditional ways. During reduction roasting, Na2CO3 reacts with gangue minerals (SiO2 and Al2O3 ), forming aluminum silicate-containing phosphorus and damaging the ore structure, which promotes the separation between iron and phosphorus during magnetic separation. Meanwhile, Na2CO3 also improves the growth of iron grains, increasing the iron grade and iron recovery. The iron concentrate, assaying 94.12wt% Fe and 0.07wt% P at the iron recovery of 96.83% and the dephosphorization rate of 74.08%, is obtained under the optimum conditions. The final product (metal iron powder) after briquetting can be used as the burden for steelmaking by an electric arc furnace to replace scrap steel.
基金financially supported by the National Natural Science Foundation of China (Nos. 51374079 and 51504053)the Hundred, Thousand and Ten Thousand Talent Project of Liaoning Province, China (No. 2014921014)+1 种基金the Postdoctoral Science Foundation of China (No. 2015M571324)China Scholarship Council for the financial support for his visiting study to the University of Alberta, Canada
文摘The effects of carbonate minerals(dolomite and siderite) on the flotation of hematite using sodium oleate as a collector were investigated through flotation tests, supplemented by dissolution measurements, solution chemistry calculations, zeta-potential measurements, Fourier transform infrared(FTIR) spectroscopic studies, and X-ray photoelectron spectroscopy(XPS) analyses. The results of flotation tests show that the presence of siderite or dolomite reduced the recovery of hematite and that the inhibiting effects of dolomite were stronger. Dissolution measurements, solution chemistry calculations, and flotation tests confirmed that both the cations(Ca^(2+) and Mg^(2+)) and CO_3^(2+)ions dissolved from dolomite depressed hematite flotation, whereas only the 23CO-ions dissolved from siderite were responsible for hematite depression. The zeta-potential, FTIR spectroscopic, and XPS analyses indicated that Ca^(2+), Mg^(2+), and CO_3^(2-)(HCO_3^-) could adsorb onto the hematite surface, thereby hindering the adsorption of sodium oleate, which was the main reason for the inhibiting effects of carbonate minerals on hematite flotation.
基金Project(50434010) supported by the National Natural Science Foundation of China
文摘According to the principle of mass balances and thermodynamic data, lg [Me]—pH diagrams (Me=Ca, Mo) for Ca-Mo-CO3-H2O system at 25 ℃ were presented with total dissolved carbon-containing ions concentrations of 0.01 mol/L and 1 mol/L, and lg [Me]—pH diagram for Ca-Mo-H2O system at 25 ℃ was also depicted. The effects of system pH value and total dissolved carbon-containing ions concentrations on the concentrations of the species in Ca-Mo-CO3-H2O system were studied. The results show that the stability region of CaMoO4 reduces significantly in the presence of sodium carbonate. In order to achieve effective leaching of molybdenum from CaMoO4, a certain concentration of sodium carbonate is necessary. High total dissolved carbon-containing ions concentrations and high pH values facilitate to the leaching of CaMoO4 and dissolved sodium carbonate is an efficient leaching agent for decomposing CaMoO4.
文摘Heterogeneous photocatalysed reduction of aqueous Na2CO3 was carried out by using nano LaCoO3 semiconductor powders. Formic acid and formaldehyde were identified as photoproducts,and were measured spectrophotometrically using Nash reagent. The effect of different parameters such as sodium carbonate concentration,amount of photocatalyst and different light sources on the yield of photoproducts was also investigated. It shows that nano LaCoO3 has photocatalytic activity. Irradiation leads to the production of electrons in the conduction band of the LaCoO3 semiconductor. It is likely that the photoproduced electrons initially reduce CO3 （2-） to HCOO -,and then to HCHO and CH3OH.
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the Institute of Particle and Science Engineering,University of Leeds and Procter&Gamble Newcastle Innovation Centre(UK)for partially funding the project
文摘Dissolution kinetics of sodium carbonate is investigated with the image analysis method at the approach of single particle.The dissolution experiments are carried out in an aqueous solution under a series of controlled temperature and p H.The selected sodium carbonate particles are all spherical with the same mass and diameter.The dissolution process is quantified with the measurement of particle diameter from dissolution images.The concentration of dissolved sodium carbonate in solvent is calculated with the measured diameter of particle.Both surface reaction model and mass transport model are implemented to determine the dissolution mechanism and quantify the dissolution rate constant at each experimental condition.According to the fitting results with both two models,it is clarified that the dissolution process at the increasing temperature is controlled by the mass transport of dissolved sodium carbonate travelling from particle surface into solvent.The dissolution process at the increasing pH is controlled by the chemical reaction on particle surface.Furthermore,the dissolution rate constant for each single spherical sodium carbonate particle is quantified and the results show that the dissolution rate constant of single spherical sodium carbonate increases significantly with the rising of temperature,but decreases with the increasing of pH conversely.
基金support of the Guangdong Basic and Applied Basic Research Foundation(grant nos.2020A1515110705 and 2021A1515110245)the China Postdoctoral Science Foundation(grant nos.2020M682711 and 2020M682710)+2 种基金the National Program for Support of Topnotch Young Professionals(grant no.x2qsA4210090)the National Natural Science Foundation of China(grant no.31971614)the State Key Laboratory of Pulp and Paper Engineering(grant no.2020C03).
文摘Room-temperature sodium–sulfur(RT/Na–S)batteries are regarded as promising large-scale stationary energy storage systems owing to their high energy density and low cost as well as the earth-abundant reserves of sodium and sulfur.However,the diffusion of polysulfides and sluggish kinetics of conversion reactions are still major challenges for their application.Herein,we developed a powerful and functional separator to inhibit the shuttle effect by coating a lightweight three-dimensional cellulose nanofiber-derived carbon aerogel on a glass fiber separator(denoted NSCA@GF).The hierarchical porous structures,favorable electronic conductivity,and three-dimensional interconnected network of N,S-codoped carbon aerogel endow a multifunctional separator with strong polysulfide anchoring capability and fast reaction kinetics of polysulfide conversion,which can act as the barrier layer and an expanded current collector to increase sulfur utilization.Moreover,the hetero-doped N/S sites are believed to strengthen polysulfide anchoring capability via chemisorption and accelerate the redox kinetics of polysulfide conversion,which is confirmed from experimental and theoretical results.As a result,the assembled Na–S coin cells with the NSCA@GF separator showed a high reversible capacity(788.8 mAh g^(−1) at 0.1 C after 100 cycles)and superior cycling stability(only 0.059%capacity decay per cycle over 1000 cycles at 1 C),thereby demonstrating the significant potential for application in high-performance RT/Na–S batteries.
文摘The Hashemite Kingdom of Jordan has a large reserve of raw Bentonite in the area of Ain Al-Baida at Basin of Al-Azraq city that has not activated yet to become valid as drilling mud. The Ore Ain AL-Baida Bentonite was investigated and activated by Na2CO3. The products were investigated by chemical analysis, X-Ray Diffraction, rheological properties and free swelling index with clay fraction. It was observed that the activities clay ranged between 0.98 < AC < 1.48 medium to high content of clay minerals. In addition, it was determined the Atterberg limits, the results of plasticity chart and relation between index and clay fraction. This means that the amount of the attracted water will be suitable influenced by the clay that is present in Ore Ain Al-Baida bentonite. The liquid limit was ranged between 83% to 140%, and plastic limit ranged between 39% - 48%. Also, rheological properties (apparent viscosity, plastic viscosity), gel strength, yield point, filtrate loss. These properties have been compared with those standard specifications properties required for the drilling fluid in order to know the appropriate circumstances to activate the Bentonite ore of Ain Al Baida at Azraq basin to become close to the standard specifications required for the drilling fluids, the ratio between Y.P/P.V was ranged 0.88 to 1.21, it is meant that the behavior of drilling fluids confirms the Bingham plastic and power-law rheological models using fine grinding of bentonite mixture with 3% - 6% concentration of sodium carbonate powder.
文摘This paper tried to develop the optimum procedure for microencapsulating water soluble solid powder with the thermal responsible material by the melting dispersion cooling method. Sodium hydrogen carbonate was adopted as a water soluble solid powder instead of microencapsulating carbon dioxide gas. The shell material was composed of olefin wax and α-tocopherol. In the experiment, the concentration of oil soluble surfactant and the water soluble surfactant species were changed. Sodium hydrogen carbonate was treated in the aqueous solution dissolving the water soluble surfactant to form the finer sodium hydrogen carbonate powder and to increase the content. The microencapsulation efficiency could be increased with the concentration of oil soluble surfactant and considerably increased by treating sodium hydrogen carbonate with the water soluble surfactant. Sodium hydrogen carbonate was protected well from environmental water. The microcapsules showed the thermal responsibility to generate carbon dioxide.
基金The authors are grateful to the National Natural Science Foundation of China for financial support.
文摘Heterogenous photocatalyzed reduction of aqueous Na2CO3 has been carried out by using nano SrFeO3 semiconductor powders. Formic acid, formaldehyde and methyl alcohol were identified as photoproducts, and were measured spectrophotometrically. The effect of the variation of different parameters such as sodium carbonate concentration, amount of photocatalyst and different light sources on the yield of photoproducts was also investigated. It shows that nano SrFeO3 has photocatalytic activity. Irradiation leads to the production of electrons in the conduction band of the SrFeO3 semiconductor. It is likely that the photoproduced electrons reduce CO32- initially to HCOO-, and then to HCHO and CH3OH.
基金financially supported by the National Nature Science Foundation of China (No. 51204054)the National Basic Research Program of China (No. 2007CB613603)the Basic Scientific Research Business Expenses Project of the Ministry of Education (No. 140204011)
文摘A novel process was developed for the preparation of ultrafine silica from potash feldspar. In the first step, potash feldspar was roasted with Na_2CO_3 and was followed by leaching using Na OH solution to increase the levels of potassium, sodium, and aluminum in the solid residue. The leaching solution was then carbonated to yield ultrafine silica. The optimized reaction conditions in the roasting process were as follows: an Na_2CO_3-to-potash feldspar molar ratio of 1.1, a reaction temperature of 875°C, and a reaction time of 1.5 h. Under these conditions, the extraction rate of SiO_2 was 98.13%. The optimized carbonation conditions included a final solution p H value of 9.0, a temperature of 40°C, a CO_2 flow rate of 6 m L/min, a stirring intensity of 600 r/min, and an ethanol-to-water volume ratio of 1:9. The precipitation rate and granularity of the SiO_2 particles were 99.63% and 200 nm, respectively. We confirmed the quality of the obtained ultrafine silica by comparing the recorded indexes with those specified in Chinese National Standard GB 25576―2010.
文摘Soddium carbonate peroxider is a compound of hydrogen peroxide and sodium carbonate. Thanks to its effectiveness in laundry, bleaching and disinfecting, sodium carbonate peroxider is very popular on the market, and is used as a contrast colour in producing reductive pigments, and as a disinfectant
