How to sustainably produce bauxite by effective reverse froth flotation of kaolinite at low temperature is an urgent problem to be solved in the field of mineral processing.In this work,a novel amino-based Gemini surf...How to sustainably produce bauxite by effective reverse froth flotation of kaolinite at low temperature is an urgent problem to be solved in the field of mineral processing.In this work,a novel amino-based Gemini surfactant butadiyl-1,4-bis(dimethyl dodecylammonium bromide)(BBDB) was prepared and first utilized as a novel collector for kaolinite flotation.Its flotation performance for kaolinite was compared with that of the common monomolecular surfactant 1-dodecylamine(DDA) by micro-flotation tests.The tests results indicated that 95% kaolinite recovery was obtained using 2.0×10^(-4) mol/L BBDB at 25℃ which was half of the dosage when DDA obtained the maximum kaolinite recovery of81%.At extremely low temperature(0℃),3.0×10^(-4) mol/L BBDB could still collect 91% kaolinite,while DDA showed a frustrating ability.The contact angle tests indicated that BBDB could still significantly improve the hydrophobicity of the kaolinite surface(contact angle 71.7°) than DDA(contact angle only25.8°) at 0℃.The Krafft point comparison tests indicated that BBDB had a much lower Krafft point(below0℃) than DDA.Fourier transform infrared spectroscopy(FTIR)-spectrum analysis and zeta potential measurements showed that BBDB was physically adsorbed on the surface of kaolinite through electrostatic interaction.展开更多
Since wolframite is usually associated with calcite,the separation and enrichment of wolframite by froth flotation remains a great challenge.Herein,a novel trisiloxane surfactant N-(2-aminoethyl)-3-ami nopropyltrisilo...Since wolframite is usually associated with calcite,the separation and enrichment of wolframite by froth flotation remains a great challenge.Herein,a novel trisiloxane surfactant N-(2-aminoethyl)-3-ami nopropyltrisiloxane(AATS)was successful synthesized,which was used for the separation of wolframite from calcite for the first time.The flotation separation performance of AATS was studied by flotation test,and its adsorption mechanism was explored based on contact angle,infrared spectrum analysis(FTIR),zeta potential and density functional theory(DFT)calculation.The results of microflotation test and binary mixed ore flotation test pointed that AATS had excellent selectivity and more prominent collection capacity for the flotation of wolframite when compared with industrial reagent sodium oleate(NaOL).The measurement results of contact angle proved that AATS improved the hydrophobicity of the wolframite surface.The highly selective adsorption mechanism of AATS surfactant on mineral surfaces were further researched and analyzed by FTIR and zeta potential.The results revealed that AATS surfactant had significant adsorption effect on wolframite,yet almost no adsorption on calcite.DFT calculation indicated that AATS produced electrostatic adsorption with wolframite surface through—N+H3 group.展开更多
A new magnetic mesoporous As(Ⅲ)adsorbent of Fe_(3)O_(4)@SiO_(2)@Ce-ZrO_(2)was prepared by solvothermal and sol^(-)gel method.The core-shell adsorbent presented a high specific surface area(168.2 m^(2)/g)and fast magn...A new magnetic mesoporous As(Ⅲ)adsorbent of Fe_(3)O_(4)@SiO_(2)@Ce-ZrO_(2)was prepared by solvothermal and sol^(-)gel method.The core-shell adsorbent presented a high specific surface area(168.2 m^(2)/g)and fast magnetic separation performance(5.37 A·m^(2)/kg).Compared with Fe_(3)O_(4)@SiO_(2)@ZrO_(2),the Ce-doped sample exhibited 12%-23%increase in As(Ⅲ)uptake over p H 3-11,which was mainly attributed to the formation of bimetal M—O—As complexes.The coexisted SO^_(4)(2-)and PO^_(4)(3-)weakened As(Ⅲ)adsorption,Ca^(2+)worked oppositely,but the impact of Cl^(-)and NO_(3)^(-)was negligible.The As(Ⅲ)maximum adsorption capacity was 24.52 mg/g at 313 K with an initial As(Ⅲ)concentration of 5 mg/L at pH 7,and its kinetics was well fitted by the pseudo-second-order model.Moreover,the adsorbent exhibited remarkable recyclability.It is suggested that Fe_(3)O_(4)@SiO_(2)@Ce-ZrO_(2)is a promising adsorbent for the advanced treatment of As(Ⅲ)contaminated wastewater.展开更多
Lithium ion batteries using Ni-Co-Mn ternary oxide materials(NCMs)and Ni-Co-Al materials(NCAs)as the cathode materials are dominantly employed to power the electric vehicles(EVs).Increasing the driving range of EVs ne...Lithium ion batteries using Ni-Co-Mn ternary oxide materials(NCMs)and Ni-Co-Al materials(NCAs)as the cathode materials are dominantly employed to power the electric vehicles(EVs).Increasing the driving range of EVs necessitates an increase of Ni content to improve the energy densities,which,however,degrades the cycle stability.Here we review the doping/coating of tungsten and related elements to improve the electrochemical performance of these cathodes especially the cycle stability.The selection of tungsten and related elements is based on their special properties including the high valence state,strong bonding with oxygen and the large ionic radius.The improvement of cycle stability mainly results from two features:(1)the enhancement of bulk structure stability upon doping(Mo,W,Ta,Nb)and(2)the resistance of side reactions of electrode/electrolyte by the surficial layer induced by direct coating(V,W,Nb)or bulk doping.For the recent high Ni materials,the formation of Ni2+and its migration to the Li layer induced by these doped/coated tungsten-related elements,and the presence of spinel or rock-salt phase before cycling contributes to improving the cycle stability.The key challenges are the selection of an optimized additive concentration and the fundamental understanding of the reaction mechanism,which will provide insightful guidance for maximizing the electrochemical performance of the state-of-the-art lithium-ion batteries at minimal additional process costs.展开更多
基金the support of the National Natural Science Foundation of China (No. U1607108)Natural Science Foundation of Jiangxi, China (No. 20202ACBL213008)。
文摘How to sustainably produce bauxite by effective reverse froth flotation of kaolinite at low temperature is an urgent problem to be solved in the field of mineral processing.In this work,a novel amino-based Gemini surfactant butadiyl-1,4-bis(dimethyl dodecylammonium bromide)(BBDB) was prepared and first utilized as a novel collector for kaolinite flotation.Its flotation performance for kaolinite was compared with that of the common monomolecular surfactant 1-dodecylamine(DDA) by micro-flotation tests.The tests results indicated that 95% kaolinite recovery was obtained using 2.0×10^(-4) mol/L BBDB at 25℃ which was half of the dosage when DDA obtained the maximum kaolinite recovery of81%.At extremely low temperature(0℃),3.0×10^(-4) mol/L BBDB could still collect 91% kaolinite,while DDA showed a frustrating ability.The contact angle tests indicated that BBDB could still significantly improve the hydrophobicity of the kaolinite surface(contact angle 71.7°) than DDA(contact angle only25.8°) at 0℃.The Krafft point comparison tests indicated that BBDB had a much lower Krafft point(below0℃) than DDA.Fourier transform infrared spectroscopy(FTIR)-spectrum analysis and zeta potential measurements showed that BBDB was physically adsorbed on the surface of kaolinite through electrostatic interaction.
基金This work was supported by the Natural Science Foundation of Jiangxi,China(Nos.20202ACBL213008 and 20202ZDB01005)。
文摘Since wolframite is usually associated with calcite,the separation and enrichment of wolframite by froth flotation remains a great challenge.Herein,a novel trisiloxane surfactant N-(2-aminoethyl)-3-ami nopropyltrisiloxane(AATS)was successful synthesized,which was used for the separation of wolframite from calcite for the first time.The flotation separation performance of AATS was studied by flotation test,and its adsorption mechanism was explored based on contact angle,infrared spectrum analysis(FTIR),zeta potential and density functional theory(DFT)calculation.The results of microflotation test and binary mixed ore flotation test pointed that AATS had excellent selectivity and more prominent collection capacity for the flotation of wolframite when compared with industrial reagent sodium oleate(NaOL).The measurement results of contact angle proved that AATS improved the hydrophobicity of the wolframite surface.The highly selective adsorption mechanism of AATS surfactant on mineral surfaces were further researched and analyzed by FTIR and zeta potential.The results revealed that AATS surfactant had significant adsorption effect on wolframite,yet almost no adsorption on calcite.DFT calculation indicated that AATS produced electrostatic adsorption with wolframite surface through—N+H3 group.
基金the financial support from the Open Research Fund of Jiangsu Key Laboratory of Resources and Environmental Information Engineering,China(No.JS201810)。
文摘A new magnetic mesoporous As(Ⅲ)adsorbent of Fe_(3)O_(4)@SiO_(2)@Ce-ZrO_(2)was prepared by solvothermal and sol^(-)gel method.The core-shell adsorbent presented a high specific surface area(168.2 m^(2)/g)and fast magnetic separation performance(5.37 A·m^(2)/kg).Compared with Fe_(3)O_(4)@SiO_(2)@ZrO_(2),the Ce-doped sample exhibited 12%-23%increase in As(Ⅲ)uptake over p H 3-11,which was mainly attributed to the formation of bimetal M—O—As complexes.The coexisted SO^_(4)(2-)and PO^_(4)(3-)weakened As(Ⅲ)adsorption,Ca^(2+)worked oppositely,but the impact of Cl^(-)and NO_(3)^(-)was negligible.The As(Ⅲ)maximum adsorption capacity was 24.52 mg/g at 313 K with an initial As(Ⅲ)concentration of 5 mg/L at pH 7,and its kinetics was well fitted by the pseudo-second-order model.Moreover,the adsorbent exhibited remarkable recyclability.It is suggested that Fe_(3)O_(4)@SiO_(2)@Ce-ZrO_(2)is a promising adsorbent for the advanced treatment of As(Ⅲ)contaminated wastewater.
基金financially supported by the Australian CRC-P project“Value-added cobalt refining technologies powering advanced batteries”,administered by Pure Battery Technologies Pty LtdAustralian Research Council through its Laureate Fellowship and Linkage Projects
文摘Lithium ion batteries using Ni-Co-Mn ternary oxide materials(NCMs)and Ni-Co-Al materials(NCAs)as the cathode materials are dominantly employed to power the electric vehicles(EVs).Increasing the driving range of EVs necessitates an increase of Ni content to improve the energy densities,which,however,degrades the cycle stability.Here we review the doping/coating of tungsten and related elements to improve the electrochemical performance of these cathodes especially the cycle stability.The selection of tungsten and related elements is based on their special properties including the high valence state,strong bonding with oxygen and the large ionic radius.The improvement of cycle stability mainly results from two features:(1)the enhancement of bulk structure stability upon doping(Mo,W,Ta,Nb)and(2)the resistance of side reactions of electrode/electrolyte by the surficial layer induced by direct coating(V,W,Nb)or bulk doping.For the recent high Ni materials,the formation of Ni2+and its migration to the Li layer induced by these doped/coated tungsten-related elements,and the presence of spinel or rock-salt phase before cycling contributes to improving the cycle stability.The key challenges are the selection of an optimized additive concentration and the fundamental understanding of the reaction mechanism,which will provide insightful guidance for maximizing the electrochemical performance of the state-of-the-art lithium-ion batteries at minimal additional process costs.
