To achieve efficient flotation separation of brucite and calcite,flotation separation experiments were conducted on two minerals using dodecylamine(DDA)as the collector and potassium dihydrogen phosphate(PDP)as the re...To achieve efficient flotation separation of brucite and calcite,flotation separation experiments were conducted on two minerals using dodecylamine(DDA)as the collector and potassium dihydrogen phosphate(PDP)as the regulator.The action mechanism of DDA and PDP was explored through contact angle measurement,zeta potential detection,solution chemistry calculation,FTIR analysis,and XPS detection.The flotation results showed that when DDA dosage was 35 mg/L and PDP dosage was 40 mg/L,the maximum floating difference between brucite and calcite was 79.81%,and the selectivity separation index was 6.46.The detection analysis showed that the main dissolved component HPO_(4)^(2−)of PDP is selectively strongly adsorbed on the Ca site on the surface of calcite,promoting the adsorption of the main dissolved component RNH_(3)^(+)of DDA on calcite surface,while brucite is basically not affected by PDP.Therefore,PDP is an effective regulator for the reverse flotation separation of brucite and calcite in DDA system.展开更多
The preparation of natural brucite nanofibers through dispersion by the wet process is described. The test results indicate that brucite fibers can be well dispersed by using sodium dioctyl sulfosuccinate （OT） as th...The preparation of natural brucite nanofibers through dispersion by the wet process is described. The test results indicate that brucite fibers can be well dispersed by using sodium dioctyl sulfosuccinate （OT） as the dispersant at a dispersant/fiber mass ratio of 0.15：1, dispersing for 30 min at a water/solid mass ratio of 20：1. The prepared nanofibers were characterized with X-ray diffraction （XRD）, scanning electron microscope （SEM）, and transmission electron microscope （TEM）. It is shown that the prepared single brucite nanofiber is around 30 nm in diameter and the talus of the nonsingle brucite nanofibers is about 50-150 nm in diameter. Natural brucite mineral fibers were treated by the dispersion method to obtain nanomaterials. These fibers have significant advantages over artificial nanofibers both in yield and in cost.展开更多
Fibrous bmcite has very unique structure and physical properties. Brucite fibers were exfoliated into single nanofibers by using dioctyl sodium sulfosuccinate （AOT） as a dispersant through mechanical agitation and u...Fibrous bmcite has very unique structure and physical properties. Brucite fibers were exfoliated into single nanofibers by using dioctyl sodium sulfosuccinate （AOT） as a dispersant through mechanical agitation and ultrasonic dispersion; and then, the nanofibers were modified by stearic acid and （3-aminopropyl）triethoxysilane （y-APS） compound modification agent. The nanofibers were characterized by using X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, Fourier transform infrared spectroscopy （FTIR）, and thermal gravimetric analysis. It is found that AOT has good effect on the dispersion. The single fiber has a consis- tent morphology, and fibrous bmcite is dispersed and modified without destroying the crystal structure. Infrared and thermal analysis shows that the surface modification of fibrous brucite is achieved by forming chemical bonds between the coupling agent and magnesium hydroxide.展开更多
Mossbauer spectra of brucite mineral from Shanxi in China were measured over a temperature range from 12 K to 500 K. Each spectrum consists of a dominant ferrous doublet and an additional ferric doublet. The most inte...Mossbauer spectra of brucite mineral from Shanxi in China were measured over a temperature range from 12 K to 500 K. Each spectrum consists of a dominant ferrous doublet and an additional ferric doublet. The most interesting result is the temperature dependence of the line broadenings at T <400 K, with the negative velocity line always more broadened than the positive one. A possible explanation of these systematic broadenings is the presence of a small magnetic perturbation in brucite.展开更多
The effect and mechanism of the removal of Pb^(2+) from an aqueous solutionby using brucite as the adsorbent were studied. It was revealed that the increase in pH of brucitesuspension, as a result of the release of ma...The effect and mechanism of the removal of Pb^(2+) from an aqueous solutionby using brucite as the adsorbent were studied. It was revealed that the increase in pH of brucitesuspension, as a result of the release of magnesium hydroxide into the suspension, leads to a sharprise of the adsorption amount of Pb^(2+) on brucite. The synergism of buffering and adsorptioncapacities of brucite is responsible for the removal of Pb^(2+) from the aqueous solution. Thecoexistence of Cu^(2+) with Pb^(2+) causes a decrease of their adsorption on brucite due to acompetition for surface sites and brucite exhibits a higher adsorption capacity for Pb^(2+) than forCu^(2+). The percentage adsorption of Pb^(2+) on brucite could reach 96.38 percent, 97.20 percentand 94.09 percent respectively with the initial pH of the suspension pH_i = 1.76 (initial Pb^(2+)concentration [Pb^(2+)]_i = 20 mumol/L), 1.82 ([Pb^(2+)]_i = 100 mumol/L) and 1.84 ([Pb^(2+)]_i =500 mumol/L). It was concluded that brucite is a very efficient mineral adsorbent for Pb^(2+)removal from polluted acidic water.展开更多
Fibrous brucite,a kind of brucite with unique structure and physical properties,was modified with stearic acid as a surface modifier.In order to investigate the mechanism of surface modification,the fixation of steari...Fibrous brucite,a kind of brucite with unique structure and physical properties,was modified with stearic acid as a surface modifier.In order to investigate the mechanism of surface modification,the fixation of stearic acid on fibrous brucite and the induced changes in surface properties were studied by using X-ray diffraction（XRD）,scanning electron microscopy（SEM）,infrared spectroscopy（IR）,Raman spectroscopy and thermo-gravimetric analysis（TGA）.XRD analysis indicates that the modification of fibrous brucite with stearic acid does not cause any changes in the structure of fibrous brucite mineral.Spectroscopy and thermal analysis show that the surfactant molecules are not only directly adsorbed on the surface of the mineral,but also chemisorbed on mineral surface by forming chemical bonds between the modifier and magnesium hydroxide.展开更多
Hydrous minerals within the subducting oceanic slab are important hosts for water.Clarification of the stability field of hydrous minerals helps to understand transport and distribution of water from the surface to th...Hydrous minerals within the subducting oceanic slab are important hosts for water.Clarification of the stability field of hydrous minerals helps to understand transport and distribution of water from the surface to the Earth’s interior.We investigated the stability of brucite,a prototype of hydrous minerals,by means of electrical conductivity measurements in both open and closed systems at 3 GPa and temperatures up to 1300 K.Dramatic increase of conductivity in association with characteristic impedance spectra suggests that partial dehydration of single-crystal brucite in the open system with a low water fugacity occurs at 950 K,which is about 300 K lower than those previously defined by phase equilibrium experiments in the closed system.By contrast,brucite completely dehydrates at 1300 K in the closed system,consistent with previous studies.Partial dehydration may generate a highly defective structure but does not lead to the breakdown of brucite to periclase and water immediately.Water activity plays a key role in the stability of hydrous minerals.Low water activity(a H_(2)O)caused by the high wetting behavior of the subducted oceanic slab at the transition zone depth may cause the partial dehydration of the dense hydrous magnesium silicates(DHMSs),which significantly reduces the temperature stability of DHMS(this mechanism has been confirmed by previous study on super hydrous phase B).As a result,the transition zone may serve as a‘dead zone’for DHMSs,and most water will be stored in wadsleyite and ringwoodite in the transition zone.展开更多
基金the General Program of the National Natural Science Foundation of China(Nos.51974064,52174239)the National Key R&D Program of China(No.2021YFC2902400)the Outstanding Postdoctoral Program of Jiangsu Province,China(No.2022ZB521).
文摘To achieve efficient flotation separation of brucite and calcite,flotation separation experiments were conducted on two minerals using dodecylamine(DDA)as the collector and potassium dihydrogen phosphate(PDP)as the regulator.The action mechanism of DDA and PDP was explored through contact angle measurement,zeta potential detection,solution chemistry calculation,FTIR analysis,and XPS detection.The flotation results showed that when DDA dosage was 35 mg/L and PDP dosage was 40 mg/L,the maximum floating difference between brucite and calcite was 79.81%,and the selectivity separation index was 6.46.The detection analysis showed that the main dissolved component HPO_(4)^(2−)of PDP is selectively strongly adsorbed on the Ca site on the surface of calcite,promoting the adsorption of the main dissolved component RNH_(3)^(+)of DDA on calcite surface,while brucite is basically not affected by PDP.Therefore,PDP is an effective regulator for the reverse flotation separation of brucite and calcite in DDA system.
基金This study was financially supported by the National High-Tech Research and Development Program of China (No.2003AA302610)
文摘The preparation of natural brucite nanofibers through dispersion by the wet process is described. The test results indicate that brucite fibers can be well dispersed by using sodium dioctyl sulfosuccinate （OT） as the dispersant at a dispersant/fiber mass ratio of 0.15：1, dispersing for 30 min at a water/solid mass ratio of 20：1. The prepared nanofibers were characterized with X-ray diffraction （XRD）, scanning electron microscope （SEM）, and transmission electron microscope （TEM）. It is shown that the prepared single brucite nanofiber is around 30 nm in diameter and the talus of the nonsingle brucite nanofibers is about 50-150 nm in diameter. Natural brucite mineral fibers were treated by the dispersion method to obtain nanomaterials. These fibers have significant advantages over artificial nanofibers both in yield and in cost.
基金financially supported by the National Natural Science Foundation of China(Nos.51274015 and 40972027)
文摘Fibrous bmcite has very unique structure and physical properties. Brucite fibers were exfoliated into single nanofibers by using dioctyl sodium sulfosuccinate （AOT） as a dispersant through mechanical agitation and ultrasonic dispersion; and then, the nanofibers were modified by stearic acid and （3-aminopropyl）triethoxysilane （y-APS） compound modification agent. The nanofibers were characterized by using X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, Fourier transform infrared spectroscopy （FTIR）, and thermal gravimetric analysis. It is found that AOT has good effect on the dispersion. The single fiber has a consis- tent morphology, and fibrous bmcite is dispersed and modified without destroying the crystal structure. Infrared and thermal analysis shows that the surface modification of fibrous brucite is achieved by forming chemical bonds between the coupling agent and magnesium hydroxide.
文摘Mossbauer spectra of brucite mineral from Shanxi in China were measured over a temperature range from 12 K to 500 K. Each spectrum consists of a dominant ferrous doublet and an additional ferric doublet. The most interesting result is the temperature dependence of the line broadenings at T <400 K, with the negative velocity line always more broadened than the positive one. A possible explanation of these systematic broadenings is the presence of a small magnetic perturbation in brucite.
基金This work was financially supported by the National Natural Science Foundation of China (No. 50272008)Talent Training Program of Beijing (No. 2003A09)
文摘The effect and mechanism of the removal of Pb^(2+) from an aqueous solutionby using brucite as the adsorbent were studied. It was revealed that the increase in pH of brucitesuspension, as a result of the release of magnesium hydroxide into the suspension, leads to a sharprise of the adsorption amount of Pb^(2+) on brucite. The synergism of buffering and adsorptioncapacities of brucite is responsible for the removal of Pb^(2+) from the aqueous solution. Thecoexistence of Cu^(2+) with Pb^(2+) causes a decrease of their adsorption on brucite due to acompetition for surface sites and brucite exhibits a higher adsorption capacity for Pb^(2+) than forCu^(2+). The percentage adsorption of Pb^(2+) on brucite could reach 96.38 percent, 97.20 percentand 94.09 percent respectively with the initial pH of the suspension pH_i = 1.76 (initial Pb^(2+)concentration [Pb^(2+)]_i = 20 mumol/L), 1.82 ([Pb^(2+)]_i = 100 mumol/L) and 1.84 ([Pb^(2+)]_i =500 mumol/L). It was concluded that brucite is a very efficient mineral adsorbent for Pb^(2+)removal from polluted acidic water.
基金Funded by National Natural Science Foundation of China(No.51274015)
文摘Fibrous brucite,a kind of brucite with unique structure and physical properties,was modified with stearic acid as a surface modifier.In order to investigate the mechanism of surface modification,the fixation of stearic acid on fibrous brucite and the induced changes in surface properties were studied by using X-ray diffraction（XRD）,scanning electron microscopy（SEM）,infrared spectroscopy（IR）,Raman spectroscopy and thermo-gravimetric analysis（TGA）.XRD analysis indicates that the modification of fibrous brucite with stearic acid does not cause any changes in the structure of fibrous brucite mineral.Spectroscopy and thermal analysis show that the surfactant molecules are not only directly adsorbed on the surface of the mineral,but also chemisorbed on mineral surface by forming chemical bonds between the modifier and magnesium hydroxide.
基金supported by CAS“Light of West China”program(Y9CR026 to X.G.)the National Natural Science Foundation of China(442072051)supported by the Ministry of Education,Culture,Sports,Science,and Technology of the Japanese Government,Grant Numbers,15H05827 and 17H01155 to T.Y.
文摘Hydrous minerals within the subducting oceanic slab are important hosts for water.Clarification of the stability field of hydrous minerals helps to understand transport and distribution of water from the surface to the Earth’s interior.We investigated the stability of brucite,a prototype of hydrous minerals,by means of electrical conductivity measurements in both open and closed systems at 3 GPa and temperatures up to 1300 K.Dramatic increase of conductivity in association with characteristic impedance spectra suggests that partial dehydration of single-crystal brucite in the open system with a low water fugacity occurs at 950 K,which is about 300 K lower than those previously defined by phase equilibrium experiments in the closed system.By contrast,brucite completely dehydrates at 1300 K in the closed system,consistent with previous studies.Partial dehydration may generate a highly defective structure but does not lead to the breakdown of brucite to periclase and water immediately.Water activity plays a key role in the stability of hydrous minerals.Low water activity(a H_(2)O)caused by the high wetting behavior of the subducted oceanic slab at the transition zone depth may cause the partial dehydration of the dense hydrous magnesium silicates(DHMSs),which significantly reduces the temperature stability of DHMS(this mechanism has been confirmed by previous study on super hydrous phase B).As a result,the transition zone may serve as a‘dead zone’for DHMSs,and most water will be stored in wadsleyite and ringwoodite in the transition zone.
