Currently a technique widely used for gold extraction is mercury by amalgamation technique, the tailing produced pollutes water of all kinds, so it is necessary to develop a form of selective mitigation, for which it ...Currently a technique widely used for gold extraction is mercury by amalgamation technique, the tailing produced pollutes water of all kinds, so it is necessary to develop a form of selective mitigation, for which it is necessary to use complexing agents based on calixarene functionalized with mercury sequestering agents. These are immobilized by adding supports based on natural silica to form polymers and make them insoluble in all types of solvents, so that they can be used as an extractor and at the same time regenerate to their original properties for continuous reuse.展开更多
Thermal barrier coating (TBC) revolutionized the industry by allowing higher operating temperatures for equipment, such as gas turbines in the aeronautical industry. However, at high temperatures, the TBC is exposed t...Thermal barrier coating (TBC) revolutionized the industry by allowing higher operating temperatures for equipment, such as gas turbines in the aeronautical industry. However, at high temperatures, the TBC is exposed to the attack of molten silicates, known as CMAS (Calcium-Magnesium-Alumino-Silicate), which are particles from the environment that infiltrate the TBC, causing delamination. In this study, samples coated with TBC by thermal spray and covered with CMAS were evaluated at temperatures of 1200˚C and 1250˚C. For each temperature, exposure times of 1 h and 5 h were used. Samples with longer exposure time had a considerable volume increase. The main contribution of this work was to demonstrate the non-wettability of the CMAS, even in the 5-h heat treatments, which prevented its infiltration in the deeper regions. The conditions to guarantee the formation of the silicate and its consequent wettability are also discussed.展开更多
This study aims to investigate the behavior of alkali activated mortar,which is made of naturally available magnesium silicate as source material.For magnesium silicate,ultrafine natural steatite powder(UFNSP)is used ...This study aims to investigate the behavior of alkali activated mortar,which is made of naturally available magnesium silicate as source material.For magnesium silicate,ultrafine natural steatite powder(UFNSP)is used as the primary source of binder,and the activation is initiated through the alkali liquid which is proportioned in various combinations of silicate to hydroxide ratio(Na_(2)SiO_(3)/Na OH)ratio,and this ratio in this study varies from 1 to 3.The UFNSP is calcined at two difierent temperatures,700 and 1000℃.The mortar mix is proportioned as 1:3 between powder and the fine aggregate,and the mortar is prepared with hydroxide molarity(M)of 10 M.The mortar is cured for 48 hours at 60℃and the compressive strength was studied.All the mix were studied for its microstructural behavior along with compressive strength.The mix proportion of the mortar,and the results obtained through microstructural characterization were combinedly formed as input for artificial neural network(ANN)predictive modelling.The model is designed to predict the compressive strength,which is trained through Bayesian regularization algorithm with varying hidden neurons of 7 to 10.This experimental and predictive study shows that the strength is influenced by both Na_(2)SiO_(3)/Na OH ratio and calcination process.And the ANN is influenced by mainly calcination temperature and uncorrelation occurs in selected samples of 1000℃calcined UFNSP mix.展开更多
In order to expand the advantages of strong durability and high compressive strength of calcium silicate hydrates(C-S-H),at the same time to make up for the poor early mechanical strength of magnesium silicate hydrate...In order to expand the advantages of strong durability and high compressive strength of calcium silicate hydrates(C-S-H),at the same time to make up for the poor early mechanical strength of magnesium silicate hydrates (M-S-H),we present the features and advantages of C-S-H and M-S-H and a comprehensive review of the progress on CaO-MgO-SiO_(2)-H_(2)O.Moreover,we systematically describe natural calcium and magnesium silicate minerals and thermodynamic properties of CaO-MgO-SiO_(2)-H_(2)O.The effect of magnesium on C-S-H and calcium on M-S-H is summarized deeply;the formation and structural feature of CaO-MgO-SiO_(2)-H_(2)O is also explained in detail.Finally,the development of calcium and magnesium silicate hydrates in the future is pointed out,and the further research is discussed and estimated.展开更多
The structures and elasticities of phase B silicates with different water and iron(Fe) content are obtained by firstprinciples simulation to understand the effects of water and Fe on their properties under high pres...The structures and elasticities of phase B silicates with different water and iron(Fe) content are obtained by firstprinciples simulation to understand the effects of water and Fe on their properties under high pressure.The lattice constants a and b decrease with increasing water content.On the contrary,c increases with increasing water content.On the other hand,the b and c decrease with increasing Fe content while a increases with increasing Fe content.The decrease of M(metal)–O octahedral volume is greater than the decrease of SiO polyhedral volume over the same pressure range.The density,bulk modulus and shear modulus of phase B increase with increasing Fe content and decrease with increasing water content.The compressional wave velocity(Vp) and shear wave velocity(Vs) of phase B decrease with increasing water and Fe content.The comparisons of density and wave velocity between phase B silicate and the Earth typical structure provide the evidence for understanding the formation of the X-discontinuity zone of the mantle.展开更多
The sediments samples were collected from the Dikrong River at various sites to assess the weathering nature and mineral characterization. The Fourier Transform Infrared (FTIR) and X-ray fluorescence (XRF) spectroscop...The sediments samples were collected from the Dikrong River at various sites to assess the weathering nature and mineral characterization. The Fourier Transform Infrared (FTIR) and X-ray fluorescence (XRF) spectroscopic techniques have been used to characterization of minerals in the sediment samples. The plagioclase index of alteration (PIA), chemical index of alteration (CIA) and index of compositional variation (ICV) are investigated for evaluating the weathering nature in the sediment. The obtained results show the presence of quartz, feldspar in different structure and kaolinite as major minerals. Carbonates and organic carbon are found as minor minerals. The correlations of SiO2 with major elements are authenticated the presence of bulk quartz grains and primary depositional environment. The presence of metamorphosed pyrophanite (MnTiO3) in the adjoined areas is reported. The presence of infrared absorption peaks in between 1611 - 1622 cm?1 in this study is indicative to the weathered metamorphic origin of the silicate minerals. The index of compositional variation indicates the presence of less clay minerals and more rock forming minerals such as plagioclase and alkali-feldspar. The obtained results exhibit the area belongs to the intermediate silicate weathering.展开更多
Investigating the immobilization of CO2,previous basalt-water-CO2 interaction studies revealed the formation of carbonates over a short period,but with the extensive formation of secondary silicates(SS).The mechanisms...Investigating the immobilization of CO2,previous basalt-water-CO2 interaction studies revealed the formation of carbonates over a short period,but with the extensive formation of secondary silicates(SS).The mechanisms involved in these processes remain unresolved,so the present study was undertaken to understand secondary mineral formation mechanisms.XRPD and Rietveld refinement data for neo-formed minerals show a drastic decrease in the Ca-O bond length,with the calcite structure degenerating after 80 h(hours).However,SEM images and EDS data revealed that a longer interaction time resulted in the formation of chlorite and smectite,adjacent to basalt grains which prevent basaltwater-CO2 interaction to form carbonates,thus restricting carbonate formation.As a result of this,the CO2 mineralization rate is initially high(till 80 h),but it later reduces drastically.It is evident that,for such temperature-controlled transformations,low temperature is conducive to minimizing SS surface coating at the time of mineral carbonation.展开更多
Li4Si O4 has been regarded as one of the most promising high-temperature CO2 sorbents.However,for practical applications,its CO2sorption kinetics,cycling stability and sorption properties at lower temperatures or lowe...Li4Si O4 has been regarded as one of the most promising high-temperature CO2 sorbents.However,for practical applications,its CO2sorption kinetics,cycling stability and sorption properties at lower temperatures or lower CO2 concentrations have to be improved.In this contribution,four Li4Si O4 sorbents were synthesized from zeolite precursors MCM-41,MCM-48,TS-1,and ZSM-5.The CO2 uptake,cycling stability and the optimal CO2 sorption conditions were investigated.Among the samples,MCM-41-Li4Si O4 showed the best cycling stability at 650°C,with a stable reversible CO2 uptake of 29.1 wt%under 100 vol%CO2 during 20 cycles.But its sorption kinetics and CO2 uptakes at lower temperatures and lower CO2 concentrations need to be improved.We then demonstrated that the sorption kinetics can be improved by modifying the MCM-41 precursor with metals such as Al,Ti,Ca,and Na.The Na-MCM-41-Li4Si O4 sample exhibited the highest sorption rate,and reached the equilibrium sorption capacity close to the theoretical value of 36.7 wt%within 20 min.In addition,we proved that coating the MCM-41-Li4Si O4with Na2CO3and K2CO3can significantly increase the CO2uptakes at lower temperatures(e.g.550℃)and lower CO2concentrations(10–20 vol%).At 550℃ and under 20 vol%CO2,15 wt%K2CO3-MCM-41-Li4Si O4 and 10 wt%Na2CO3-MCM-41-Li4Si O4 sorbents resulted in a CO2 uptake of 32.2 wt%and 34.7 wt%,respectively,which are much higher than that of MCM-41-Li4Si O4(11.8 wt%).These two sorbents also showed good cycling stability.The promoiting mechasnim by alkali carbonate coating was discussed by a doubleshell model.展开更多
In this work, different magnesium silicate mineral samples based on antigorite, lizardite, chrysotile(which have the same general formula Mg3Si2O5(OH)4), and talc(Mg3Si4O10(OH)2) were reacted with KOH to prepare catal...In this work, different magnesium silicate mineral samples based on antigorite, lizardite, chrysotile(which have the same general formula Mg3Si2O5(OH)4), and talc(Mg3Si4O10(OH)2) were reacted with KOH to prepare catalysts for biodiesel production. Simple impregnation with 20 wt% K and treatment at 700–900°C led to a solid-state reaction to mainly form the K2MgSiO4 phase in all samples. These results indicate that the K ion can diffuse into the different Mg silicate structures and textures, likely through intercalation in the interlayer space of the different mineral samples followed by dehydroxylation and K2MgSiO4 formation. All the materials showed catalytic activity for the transesterification of soybean oil(1:6 of oil : methanol molar ratio, 5 wt% of catalyst, 60°C). However, the best results were obtained for the antigorite and chrysotile precursors, which are discussed in terms of mineral structure and the more efficient formation of the active phase K2MgSiO4.展开更多
The strength development law of γ-type dicalcium silicate (γ-C_(2)S) under different carbonation processes was investigated,and the carbonation mechanism of γ-C_(2)S under the action of NH_(4)HCO_(3) was clarified ...The strength development law of γ-type dicalcium silicate (γ-C_(2)S) under different carbonation processes was investigated,and the carbonation mechanism of γ-C_(2)S under the action of NH_(4)HCO_(3) was clarified by using a wide range of test methods,including XRD and SEM.A method of saturated NH_(4)HCO_(3) solution as a curing agent was identified to improve the carbonation efficiency and enhance the carbonation degree of γ-C_(2)S,and then a high-strength carbonated specimen was obtained.Microhardness analysis and SEM morphology analysis were conducted on the carbonised specimens obtained under atmospheric pressure carbonisation conditions using the curing agent.It was found that γ-C_(2)S could perform carbonisation well under atmospheric pressure,which promoted the carbonisation efficiency and decreased the carbonisation cost simultaneously.Therefore,a new carbonisation process solution was proposed for the rapid carbonisation of γ-C_(2)S.展开更多
The only occurrence of Lower Triassic silicic volcanic rocks within the South China Block is in the Qinzhou Bay area of Guangxi Province.LA-ICP-MS zircon U-Pb dating reveals that volcanic rocks of the Beisi and Banba ...The only occurrence of Lower Triassic silicic volcanic rocks within the South China Block is in the Qinzhou Bay area of Guangxi Province.LA-ICP-MS zircon U-Pb dating reveals that volcanic rocks of the Beisi and Banba formations formed between 248.8±1.6 and 246.5±1.3 Ma,coeval with peraluminous granites of the Qinzhou Bay Granitic Complex.The studied rhyolites and dacites are characterized by high SiO_(2),K_(2)O,and Al_(2)O_(3),and low MgO,CaO,and P_(2)O_(5) contents and are classified as high-K calc-alkaline S-type rocks,with A/CNK=0.98-1.19.The volcanic rocks are depleted in high field strength elements,e.g.,Nb,Ta,Ti,and P,and enriched in large ion lithophile elements,e.g.,Rb,K,Sr,and Ba.Although the analyzed volcanic rocks have extremely enriched zircon Hf isotopic compositions(ε_(Hf)(t)=-29.1 to-6.9),source discrimination indicators and high calculated Ti-in-zircon temperatures(798-835℃)reveal that magma derived from enriched lithospheric mantle not only provided a heat source for anatectic melting of the metasedimentary protoliths but was also an endmember component of the S-type silicic magma.The studied early Triassic volcanics are inferred to have formed immediately before closure of the Paleo-Tethys Ocean in this region,as the associated subduction would have generated an extensional setting in which the mantle-derived upwelling and volcanic activity occurred.展开更多
Calcium silicate hydrate(C-S-H)is the mainly strength source of cement-based materials,but there is little basic research.In this paper,molecular dynamics method is applied to analyze the multi-scale tensile strength ...Calcium silicate hydrate(C-S-H)is the mainly strength source of cement-based materials,but there is little basic research.In this paper,molecular dynamics method is applied to analyze the multi-scale tensile strength and tensile strain of C-S-H layered materials under the condition of external physical fields(temperature and strain rate).The results show that the tensile strength and strain of C-S-H model decrease with temperature raises.The temperature(from 1 K to 600 K)has obvious influence on the tensile strain and strength of C-S-H layered materials.In addition,at(0.00025 ps^(-1)-0.001 ps^(-1)),the tensile strain and strength of C-S-H layered materials are less sensitive to strain rate.The whole model is closer to a 3-dimensional deformation.However,at(0.001 ps^(-1)-0.005 ps^(-1)),the dynamic load effect begins to increase,and the work done by the load per unit time increased.The tensile strain and strength of C-S-H layered materials indicates intensified by the change of strain rate.The energies are randomly distributed in the system,not concentrated in a certain area.展开更多
Inhibitors are important for flotation separation of quartz and feldspar.In this study,a novel combined inhibitor was used to separate quartz and feldspar in near-neutral pulp.Selective inhibition of the combined inhi...Inhibitors are important for flotation separation of quartz and feldspar.In this study,a novel combined inhibitor was used to separate quartz and feldspar in near-neutral pulp.Selective inhibition of the combined inhibitor was assessed by micro-flotation experiments.And a series of detection methods were used to detect differences in the surface properties of feldspars and quartz after flotation reagents and put forward the synergistic strengthening mechanism.The outcomes were pointed out that pre-mixing combined inhibitors were more effective than the addition of Ca^(2+)and SS in sequence under the optimal proportion of 1:5.A concentrate from artificial mixed minerals that was characterized by a high quartz grade and a high recovery was acquired,and was found to be 90.70wt% and 83.70%,respectively.It was demonstrated that the combined inhibitor selectively prevented the action of the collector and feldspar from Fourier-transform infrared(FT-IR)and adsorption capacity tests.The results of X-ray photoelectron spectroscopy(XPS)indicated that Ca^(2+)directly interacts with the surface of quartz to increase the adsorption of collectors.In contrast,the chemistry property of Al on the feldspar surface was altered by combined inhibitor due to Na^(+)and Ca^(2+)taking the place of K^(+),resulting in the composite inhibitor forms a hydrophilic structure,which prevents the adsorption of the collector on the surface of feldspar by interacting with the Al active site.The combination of Ca^(2+)and SS synergically strengthens the difference of collecting property between quartz and feldspar by collector,thus achieving the effect of efficient separation.A new strategy for flotation to separate quartz from feldspar in near-neutral pulp was provided.展开更多
Mostly fed with grass in fresh or conserved form,cattle and other livestock have to cope with silicate defence bodies from plants(phytoliths)and environmental silicates(grit),which abrade tooth enamel and could additi...Mostly fed with grass in fresh or conserved form,cattle and other livestock have to cope with silicate defence bodies from plants(phytoliths)and environmental silicates(grit),which abrade tooth enamel and could additionally interact with various salivary proteins.To detect potential candidates for silicate-binding proteins,bovine whole saliva was incubated with grass-derived phytoliths and silicates.Interactions of salivary proteins with pulverized bovine dental enamel and dentine were additionally analysed.After intense washing,the powder fractions were loaded onto 1D-polyacrylamide gels,most prominent adhesive protein bands were cut out and proteins were identified by mass spectrometry within three independent replicates.All materials were mainly bound by bovine odorant-binding protein,bovine salivary protein 30×10^(3) and carbonic anhydrase VI.The phytolith/silicate fraction showed additional stronger interaction with haemoglobinβand lactoperoxidase.Conceivably,the binding of these proteins to the surfaces may contribute to biological processes occurring on them.展开更多
The influence of sodium silicate on the corrosion behaviour of aluminium alloy 7075-T6 in 0.1 M sodium chloride solution was studied by open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) tec...The influence of sodium silicate on the corrosion behaviour of aluminium alloy 7075-T6 in 0.1 M sodium chloride solution was studied by open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) techniques. Scanning electron microscopy (SEM) was used to characterize the AA7075-T6 surface. Silicate can significantly reduce corrosion deterioration and the inhibition efficiency increases with the concentration of Na<sub>2</sub>SiO<sub>3</sub>. The corrosion inhibition mechanism involves the formation of a protective film over the alloy surface by adsorption of aluminosilicate anions from solution, as has also been suggested by others in literature.展开更多
文摘Currently a technique widely used for gold extraction is mercury by amalgamation technique, the tailing produced pollutes water of all kinds, so it is necessary to develop a form of selective mitigation, for which it is necessary to use complexing agents based on calixarene functionalized with mercury sequestering agents. These are immobilized by adding supports based on natural silica to form polymers and make them insoluble in all types of solvents, so that they can be used as an extractor and at the same time regenerate to their original properties for continuous reuse.
文摘Thermal barrier coating (TBC) revolutionized the industry by allowing higher operating temperatures for equipment, such as gas turbines in the aeronautical industry. However, at high temperatures, the TBC is exposed to the attack of molten silicates, known as CMAS (Calcium-Magnesium-Alumino-Silicate), which are particles from the environment that infiltrate the TBC, causing delamination. In this study, samples coated with TBC by thermal spray and covered with CMAS were evaluated at temperatures of 1200˚C and 1250˚C. For each temperature, exposure times of 1 h and 5 h were used. Samples with longer exposure time had a considerable volume increase. The main contribution of this work was to demonstrate the non-wettability of the CMAS, even in the 5-h heat treatments, which prevented its infiltration in the deeper regions. The conditions to guarantee the formation of the silicate and its consequent wettability are also discussed.
文摘This study aims to investigate the behavior of alkali activated mortar,which is made of naturally available magnesium silicate as source material.For magnesium silicate,ultrafine natural steatite powder(UFNSP)is used as the primary source of binder,and the activation is initiated through the alkali liquid which is proportioned in various combinations of silicate to hydroxide ratio(Na_(2)SiO_(3)/Na OH)ratio,and this ratio in this study varies from 1 to 3.The UFNSP is calcined at two difierent temperatures,700 and 1000℃.The mortar mix is proportioned as 1:3 between powder and the fine aggregate,and the mortar is prepared with hydroxide molarity(M)of 10 M.The mortar is cured for 48 hours at 60℃and the compressive strength was studied.All the mix were studied for its microstructural behavior along with compressive strength.The mix proportion of the mortar,and the results obtained through microstructural characterization were combinedly formed as input for artificial neural network(ANN)predictive modelling.The model is designed to predict the compressive strength,which is trained through Bayesian regularization algorithm with varying hidden neurons of 7 to 10.This experimental and predictive study shows that the strength is influenced by both Na_(2)SiO_(3)/Na OH ratio and calcination process.And the ANN is influenced by mainly calcination temperature and uncorrelation occurs in selected samples of 1000℃calcined UFNSP mix.
基金Funded by Natural Science Basic Research Plan in Shaanxi Province of China (Nos.2021JQ-500, 2021GY-203, 2023-JCYB-096)Shaanxi Provincial Education Department of Key Scientific Research Plan (No.20JS079)Shaanxi Provincial Education Department of Normal Scientific Research Plan (No.20JK0727)。
文摘In order to expand the advantages of strong durability and high compressive strength of calcium silicate hydrates(C-S-H),at the same time to make up for the poor early mechanical strength of magnesium silicate hydrates (M-S-H),we present the features and advantages of C-S-H and M-S-H and a comprehensive review of the progress on CaO-MgO-SiO_(2)-H_(2)O.Moreover,we systematically describe natural calcium and magnesium silicate minerals and thermodynamic properties of CaO-MgO-SiO_(2)-H_(2)O.The effect of magnesium on C-S-H and calcium on M-S-H is summarized deeply;the formation and structural feature of CaO-MgO-SiO_(2)-H_(2)O is also explained in detail.Finally,the development of calcium and magnesium silicate hydrates in the future is pointed out,and the further research is discussed and estimated.
基金Project supported by the Science Fund from the Key Laboratory of Earthquake Prediction,Institute of Earthquake Science,China Earthquake Administration(Grant No.2016IES010104)the National Natural Science Foundation of China(Grant Nos.41174071,41273073,41373060,and 41573121)
文摘The structures and elasticities of phase B silicates with different water and iron(Fe) content are obtained by firstprinciples simulation to understand the effects of water and Fe on their properties under high pressure.The lattice constants a and b decrease with increasing water content.On the contrary,c increases with increasing water content.On the other hand,the b and c decrease with increasing Fe content while a increases with increasing Fe content.The decrease of M(metal)–O octahedral volume is greater than the decrease of SiO polyhedral volume over the same pressure range.The density,bulk modulus and shear modulus of phase B increase with increasing Fe content and decrease with increasing water content.The compressional wave velocity(Vp) and shear wave velocity(Vs) of phase B decrease with increasing water and Fe content.The comparisons of density and wave velocity between phase B silicate and the Earth typical structure provide the evidence for understanding the formation of the X-discontinuity zone of the mantle.
文摘The sediments samples were collected from the Dikrong River at various sites to assess the weathering nature and mineral characterization. The Fourier Transform Infrared (FTIR) and X-ray fluorescence (XRF) spectroscopic techniques have been used to characterization of minerals in the sediment samples. The plagioclase index of alteration (PIA), chemical index of alteration (CIA) and index of compositional variation (ICV) are investigated for evaluating the weathering nature in the sediment. The obtained results show the presence of quartz, feldspar in different structure and kaolinite as major minerals. Carbonates and organic carbon are found as minor minerals. The correlations of SiO2 with major elements are authenticated the presence of bulk quartz grains and primary depositional environment. The presence of metamorphosed pyrophanite (MnTiO3) in the adjoined areas is reported. The presence of infrared absorption peaks in between 1611 - 1622 cm?1 in this study is indicative to the weathered metamorphic origin of the silicate minerals. The index of compositional variation indicates the presence of less clay minerals and more rock forming minerals such as plagioclase and alkali-feldspar. The obtained results exhibit the area belongs to the intermediate silicate weathering.
基金financial support in the form of a Project Grant (IS-STAC/CO2-SR-79/10/G)
文摘Investigating the immobilization of CO2,previous basalt-water-CO2 interaction studies revealed the formation of carbonates over a short period,but with the extensive formation of secondary silicates(SS).The mechanisms involved in these processes remain unresolved,so the present study was undertaken to understand secondary mineral formation mechanisms.XRPD and Rietveld refinement data for neo-formed minerals show a drastic decrease in the Ca-O bond length,with the calcite structure degenerating after 80 h(hours).However,SEM images and EDS data revealed that a longer interaction time resulted in the formation of chlorite and smectite,adjacent to basalt grains which prevent basaltwater-CO2 interaction to form carbonates,thus restricting carbonate formation.As a result of this,the CO2 mineralization rate is initially high(till 80 h),but it later reduces drastically.It is evident that,for such temperature-controlled transformations,low temperature is conducive to minimizing SS surface coating at the time of mineral carbonation.
基金supported by the National Natural Science Foundation of China (51622801, 51572029)Beijing Excellent Young Scholar (2015000026833ZK11)the Beijing Natural Science Foundation (2184114)
文摘Li4Si O4 has been regarded as one of the most promising high-temperature CO2 sorbents.However,for practical applications,its CO2sorption kinetics,cycling stability and sorption properties at lower temperatures or lower CO2 concentrations have to be improved.In this contribution,four Li4Si O4 sorbents were synthesized from zeolite precursors MCM-41,MCM-48,TS-1,and ZSM-5.The CO2 uptake,cycling stability and the optimal CO2 sorption conditions were investigated.Among the samples,MCM-41-Li4Si O4 showed the best cycling stability at 650°C,with a stable reversible CO2 uptake of 29.1 wt%under 100 vol%CO2 during 20 cycles.But its sorption kinetics and CO2 uptakes at lower temperatures and lower CO2 concentrations need to be improved.We then demonstrated that the sorption kinetics can be improved by modifying the MCM-41 precursor with metals such as Al,Ti,Ca,and Na.The Na-MCM-41-Li4Si O4 sample exhibited the highest sorption rate,and reached the equilibrium sorption capacity close to the theoretical value of 36.7 wt%within 20 min.In addition,we proved that coating the MCM-41-Li4Si O4with Na2CO3and K2CO3can significantly increase the CO2uptakes at lower temperatures(e.g.550℃)and lower CO2concentrations(10–20 vol%).At 550℃ and under 20 vol%CO2,15 wt%K2CO3-MCM-41-Li4Si O4 and 10 wt%Na2CO3-MCM-41-Li4Si O4 sorbents resulted in a CO2 uptake of 32.2 wt%and 34.7 wt%,respectively,which are much higher than that of MCM-41-Li4Si O4(11.8 wt%).These two sorbents also showed good cycling stability.The promoiting mechasnim by alkali carbonate coating was discussed by a doubleshell model.
文摘In this work, different magnesium silicate mineral samples based on antigorite, lizardite, chrysotile(which have the same general formula Mg3Si2O5(OH)4), and talc(Mg3Si4O10(OH)2) were reacted with KOH to prepare catalysts for biodiesel production. Simple impregnation with 20 wt% K and treatment at 700–900°C led to a solid-state reaction to mainly form the K2MgSiO4 phase in all samples. These results indicate that the K ion can diffuse into the different Mg silicate structures and textures, likely through intercalation in the interlayer space of the different mineral samples followed by dehydroxylation and K2MgSiO4 formation. All the materials showed catalytic activity for the transesterification of soybean oil(1:6 of oil : methanol molar ratio, 5 wt% of catalyst, 60°C). However, the best results were obtained for the antigorite and chrysotile precursors, which are discussed in terms of mineral structure and the more efficient formation of the active phase K2MgSiO4.
基金Funded by Hubei Technology Innovation Key Program (No.2018AAA004)。
文摘The strength development law of γ-type dicalcium silicate (γ-C_(2)S) under different carbonation processes was investigated,and the carbonation mechanism of γ-C_(2)S under the action of NH_(4)HCO_(3) was clarified by using a wide range of test methods,including XRD and SEM.A method of saturated NH_(4)HCO_(3) solution as a curing agent was identified to improve the carbonation efficiency and enhance the carbonation degree of γ-C_(2)S,and then a high-strength carbonated specimen was obtained.Microhardness analysis and SEM morphology analysis were conducted on the carbonised specimens obtained under atmospheric pressure carbonisation conditions using the curing agent.It was found that γ-C_(2)S could perform carbonisation well under atmospheric pressure,which promoted the carbonisation efficiency and decreased the carbonisation cost simultaneously.Therefore,a new carbonisation process solution was proposed for the rapid carbonisation of γ-C_(2)S.
基金supported by the Guangxi Natural Science Foundation Program(Grant Nos.2021GXNSFAA220077,2021GXNSFBA220063)the Natural Science Foundation of China(Grant No.42073031)。
文摘The only occurrence of Lower Triassic silicic volcanic rocks within the South China Block is in the Qinzhou Bay area of Guangxi Province.LA-ICP-MS zircon U-Pb dating reveals that volcanic rocks of the Beisi and Banba formations formed between 248.8±1.6 and 246.5±1.3 Ma,coeval with peraluminous granites of the Qinzhou Bay Granitic Complex.The studied rhyolites and dacites are characterized by high SiO_(2),K_(2)O,and Al_(2)O_(3),and low MgO,CaO,and P_(2)O_(5) contents and are classified as high-K calc-alkaline S-type rocks,with A/CNK=0.98-1.19.The volcanic rocks are depleted in high field strength elements,e.g.,Nb,Ta,Ti,and P,and enriched in large ion lithophile elements,e.g.,Rb,K,Sr,and Ba.Although the analyzed volcanic rocks have extremely enriched zircon Hf isotopic compositions(ε_(Hf)(t)=-29.1 to-6.9),source discrimination indicators and high calculated Ti-in-zircon temperatures(798-835℃)reveal that magma derived from enriched lithospheric mantle not only provided a heat source for anatectic melting of the metasedimentary protoliths but was also an endmember component of the S-type silicic magma.The studied early Triassic volcanics are inferred to have formed immediately before closure of the Paleo-Tethys Ocean in this region,as the associated subduction would have generated an extensional setting in which the mantle-derived upwelling and volcanic activity occurred.
基金This work was supported by a Natural Science Foundation of Zhejiang Province(LQ23E080003)Innovative training program for college students.
文摘Calcium silicate hydrate(C-S-H)is the mainly strength source of cement-based materials,but there is little basic research.In this paper,molecular dynamics method is applied to analyze the multi-scale tensile strength and tensile strain of C-S-H layered materials under the condition of external physical fields(temperature and strain rate).The results show that the tensile strength and strain of C-S-H model decrease with temperature raises.The temperature(from 1 K to 600 K)has obvious influence on the tensile strain and strength of C-S-H layered materials.In addition,at(0.00025 ps^(-1)-0.001 ps^(-1)),the tensile strain and strength of C-S-H layered materials are less sensitive to strain rate.The whole model is closer to a 3-dimensional deformation.However,at(0.001 ps^(-1)-0.005 ps^(-1)),the dynamic load effect begins to increase,and the work done by the load per unit time increased.The tensile strain and strength of C-S-H layered materials indicates intensified by the change of strain rate.The energies are randomly distributed in the system,not concentrated in a certain area.
基金the financial support from the National Key Research and Development Program of China(No.2018YFC1903403)Young Elite Scientists Sponsorship Program by CAST(No.2022QNRC001).
文摘Inhibitors are important for flotation separation of quartz and feldspar.In this study,a novel combined inhibitor was used to separate quartz and feldspar in near-neutral pulp.Selective inhibition of the combined inhibitor was assessed by micro-flotation experiments.And a series of detection methods were used to detect differences in the surface properties of feldspars and quartz after flotation reagents and put forward the synergistic strengthening mechanism.The outcomes were pointed out that pre-mixing combined inhibitors were more effective than the addition of Ca^(2+)and SS in sequence under the optimal proportion of 1:5.A concentrate from artificial mixed minerals that was characterized by a high quartz grade and a high recovery was acquired,and was found to be 90.70wt% and 83.70%,respectively.It was demonstrated that the combined inhibitor selectively prevented the action of the collector and feldspar from Fourier-transform infrared(FT-IR)and adsorption capacity tests.The results of X-ray photoelectron spectroscopy(XPS)indicated that Ca^(2+)directly interacts with the surface of quartz to increase the adsorption of collectors.In contrast,the chemistry property of Al on the feldspar surface was altered by combined inhibitor due to Na^(+)and Ca^(2+)taking the place of K^(+),resulting in the composite inhibitor forms a hydrophilic structure,which prevents the adsorption of the collector on the surface of feldspar by interacting with the Al active site.The combination of Ca^(2+)and SS synergically strengthens the difference of collecting property between quartz and feldspar by collector,thus achieving the effect of efficient separation.A new strategy for flotation to separate quartz from feldspar in near-neutral pulp was provided.
基金This research was supported by the German Research Foundation(DFG,SU 124/15-1).
文摘Mostly fed with grass in fresh or conserved form,cattle and other livestock have to cope with silicate defence bodies from plants(phytoliths)and environmental silicates(grit),which abrade tooth enamel and could additionally interact with various salivary proteins.To detect potential candidates for silicate-binding proteins,bovine whole saliva was incubated with grass-derived phytoliths and silicates.Interactions of salivary proteins with pulverized bovine dental enamel and dentine were additionally analysed.After intense washing,the powder fractions were loaded onto 1D-polyacrylamide gels,most prominent adhesive protein bands were cut out and proteins were identified by mass spectrometry within three independent replicates.All materials were mainly bound by bovine odorant-binding protein,bovine salivary protein 30×10^(3) and carbonic anhydrase VI.The phytolith/silicate fraction showed additional stronger interaction with haemoglobinβand lactoperoxidase.Conceivably,the binding of these proteins to the surfaces may contribute to biological processes occurring on them.
文摘The influence of sodium silicate on the corrosion behaviour of aluminium alloy 7075-T6 in 0.1 M sodium chloride solution was studied by open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) techniques. Scanning electron microscopy (SEM) was used to characterize the AA7075-T6 surface. Silicate can significantly reduce corrosion deterioration and the inhibition efficiency increases with the concentration of Na<sub>2</sub>SiO<sub>3</sub>. The corrosion inhibition mechanism involves the formation of a protective film over the alloy surface by adsorption of aluminosilicate anions from solution, as has also been suggested by others in literature.