In order to expand the application of the basic magnesium carbonate in the field of flame retardant,the plate-like basic magnesium carbonate(Mg5(CO3)4(OH)2.4H2O)was prepared successfully by template-mediated/homogeneo...In order to expand the application of the basic magnesium carbonate in the field of flame retardant,the plate-like basic magnesium carbonate(Mg5(CO3)4(OH)2.4H2O)was prepared successfully by template-mediated/homogeneous precipitation method,using magnesium chloride hexahydrate(MgCl2.6H2O)and urea(CO(NH2)2)as reaction materials.Phase and morphology of the product were characterized by X-ray diffraction(XRD),scanning electron microscope(SEM)and atomic force microscope(AFM),respectively.The results showed that well-crystallized plate-like Mg5(CO3)4(OH)2.4H2O can be prepared at the water bath temperature of 100°C,water bath time of 24 h,the aging time of 5 h after adding organic template agent.The investigation on organic template mediated mechanism shows that the template affects the crystal morphology by changing surface energy of different crystal plane.Through a preliminary study on the growth mechanism of the product,it is found that the generation of the plate-like Mg5(CO3)4(OH)2.4H2O could be explained by two-dimensional nucleation/step growth mechanism.展开更多
The thermal decomposition process of basic magnesium carbonate was investigated. Firstly, Basic magnesium carbonate was prepared from magnesite, and the characteristics of the product were detected by X-ray diffracti...The thermal decomposition process of basic magnesium carbonate was investigated. Firstly, Basic magnesium carbonate was prepared from magnesite, and the characteristics of the product were detected by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. Subsequently, the thermal decomposition process of basic magnesium carbonate in air was studied by thermogravimetry-differential thermogravimetry （TG-DTG）. The results of XRD confirm that the chemical composition of basic magnesium carbonate is 4MgCO3·Mg（OH）2·4H2O. And the SEM images show that the sample is in sheet structure, with a diameter of 0.1-1 μm. The TG-DTG results demonstrate that there are two steps in the thermal decomposition process of basic magnesium carbonate. The apparent activation energies （E） were calculated by Flyrm-Wall-Ozawa method. It is obtained from Coats-Redfem＇s equation and Malek method that the mechanism functions of the two decomposition stages are D3 and A1.5, respectively. And then, the kinetic equations of the two steps were deduced as well.展开更多
The flake-like basic magnesium carbonate was prepared from the ammonium sulfate leaching liquid of asbestos tailings. The method of X-ray diffraction, Fourier transform infrared spectra, TA-DTG and SEM analysis had be...The flake-like basic magnesium carbonate was prepared from the ammonium sulfate leaching liquid of asbestos tailings. The method of X-ray diffraction, Fourier transform infrared spectra, TA-DTG and SEM analysis had been used to research the influence of the reaction temperature on the phase, structure and morphology of the product during the preparation of the basic magnesium carbonate. The results indicates that the product was needle-like magnesium carbonate hydrate at the lower reaction temperature (from 35 ℃ to 65℃), with the increase of the reaction temperature (75 ℃ to 95 ℃ ), the needle-like magnesium carbonate hydrate (MgCO3·xH2O) transformed to flake-like basic magnesium carbonate [Mg5(CO3)4(OH)2·4H2O], the reaction temperature plays an important role in the preparation of flake-like basic magnesium carbonate, the preparation of flake-like basic magnesium carbonate was a nucleation-dissolution-recrystallization growth mechanism process.展开更多
Layered double hydroxides(LDHs)have received extensive attention in many fields such as catalysis,environmental management and medical applications.Typically,expensive soluble metal salts are commonly used as the star...Layered double hydroxides(LDHs)have received extensive attention in many fields such as catalysis,environmental management and medical applications.Typically,expensive soluble metal salts are commonly used as the starting materials for the synthesis of LDHs.Here,we report a novel synthesis route for Mg/Al-LDH by using inexpensive basic magnesium carbonate as the starting material.X-ray diffraction(XRD)and solid-state nuclear magnetic resonance(ssNMR)data show that LDHs with rich defects are formed rapidly at room temperature and good crystallinity can be obtained after further hydrothermal treatment.These results provide a simple,rapid and green preparation method for LDHs.展开更多
Basic magnesium carbonate microspheres with a red blood cell （RBC）-like appearance and diameters of ~3μm were synthesized by amphiphilic molecule-participated self-assembly under hydrothermal conditions, In the sel...Basic magnesium carbonate microspheres with a red blood cell （RBC）-like appearance and diameters of ~3μm were synthesized by amphiphilic molecule-participated self-assembly under hydrothermal conditions, In the self-assembly, sodium dodecyl benzene sulfonate served as a template for the formation of Mg（OH）2 spherical micelles and also as a reactant precursor that releases CO2 to react with Mg（OH）2. The growth of the microspheres is driven by the continuous generation of new hydrophobic centers because of the consumption of hydrophilic poles （--SO3-）. The surfactant-directed self-assembly can be applied to the synthesis of other carbonate or metallic oxide self-assemblies, indicating that it is a universal self-assembly method for amphiphilic molecules.展开更多
Basic magnesium carbonate(4 MgCO3·Mg(OH)2·4 H2 O) with spherical-like structure was synthesized through precursors thermal decomposition. The precursor of magnesium carbonate trihydrates(MgCO3·3 H2 O) w...Basic magnesium carbonate(4 MgCO3·Mg(OH)2·4 H2 O) with spherical-like structure was synthesized through precursors thermal decomposition. The precursor of magnesium carbonate trihydrates(MgCO3·3 H2 O) was synthesized by brine and ammonium bicarbonate, and the thermal decomposition conditions were investigated in detail. The obtained particulate was characterized using SEM, XRD and laser particle analyzer. The result showed that it was easy to obtain spherical-like 4 MgCO3·Mg(OH)2·4 H2 O by precursor thermal decomposition at 80~100 ℃ with thermal decomposition time 90 min, stirring time 15 min and the liquid initial concentration 0.1 mol/L, while rod-like 4 MgCO3·Mg(OH)2·4 H2 O with a surface of "house of card" structure was more likely to be obtained at low temperature(55 ℃), and rosette-like products were obtained at a little higher temperature(80 ℃) by direct synthesis.展开更多
以碱式碳酸镁为原料,采用微波辐射煅烧制备轻质活性氧化镁是可行的,正交实验结果表明,影响碱式碳酸镁分解的主要因素是微波功率,其次是煅烧时间,物料质量影响最小。确定了最佳实验工艺条件为:微波功率490 W,煅烧时间12 m in,物料质量2 g...以碱式碳酸镁为原料,采用微波辐射煅烧制备轻质活性氧化镁是可行的,正交实验结果表明,影响碱式碳酸镁分解的主要因素是微波功率,其次是煅烧时间,物料质量影响最小。确定了最佳实验工艺条件为:微波功率490 W,煅烧时间12 m in,物料质量2 g,碱式碳酸镁的分解率为93.81%,活性氧化镁的碘吸附值为72.56 mg/g。展开更多
基金Project(51374155)supported by the National Natural Science Foundation of ChinaProject(2014BCB034)supported by the Hubei Province Key Technology R&D Program,ChinaProject(2014CFB796)supported by the Natural Science Foundation of Hubei Province of China
文摘In order to expand the application of the basic magnesium carbonate in the field of flame retardant,the plate-like basic magnesium carbonate(Mg5(CO3)4(OH)2.4H2O)was prepared successfully by template-mediated/homogeneous precipitation method,using magnesium chloride hexahydrate(MgCl2.6H2O)and urea(CO(NH2)2)as reaction materials.Phase and morphology of the product were characterized by X-ray diffraction(XRD),scanning electron microscope(SEM)and atomic force microscope(AFM),respectively.The results showed that well-crystallized plate-like Mg5(CO3)4(OH)2.4H2O can be prepared at the water bath temperature of 100°C,water bath time of 24 h,the aging time of 5 h after adding organic template agent.The investigation on organic template mediated mechanism shows that the template affects the crystal morphology by changing surface energy of different crystal plane.Through a preliminary study on the growth mechanism of the product,it is found that the generation of the plate-like Mg5(CO3)4(OH)2.4H2O could be explained by two-dimensional nucleation/step growth mechanism.
基金Project(20876160) supported by the National Natural Science Foundation of China
文摘The thermal decomposition process of basic magnesium carbonate was investigated. Firstly, Basic magnesium carbonate was prepared from magnesite, and the characteristics of the product were detected by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. Subsequently, the thermal decomposition process of basic magnesium carbonate in air was studied by thermogravimetry-differential thermogravimetry （TG-DTG）. The results of XRD confirm that the chemical composition of basic magnesium carbonate is 4MgCO3·Mg（OH）2·4H2O. And the SEM images show that the sample is in sheet structure, with a diameter of 0.1-1 μm. The TG-DTG results demonstrate that there are two steps in the thermal decomposition process of basic magnesium carbonate. The apparent activation energies （E） were calculated by Flyrm-Wall-Ozawa method. It is obtained from Coats-Redfem＇s equation and Malek method that the mechanism functions of the two decomposition stages are D3 and A1.5, respectively. And then, the kinetic equations of the two steps were deduced as well.
文摘The flake-like basic magnesium carbonate was prepared from the ammonium sulfate leaching liquid of asbestos tailings. The method of X-ray diffraction, Fourier transform infrared spectra, TA-DTG and SEM analysis had been used to research the influence of the reaction temperature on the phase, structure and morphology of the product during the preparation of the basic magnesium carbonate. The results indicates that the product was needle-like magnesium carbonate hydrate at the lower reaction temperature (from 35 ℃ to 65℃), with the increase of the reaction temperature (75 ℃ to 95 ℃ ), the needle-like magnesium carbonate hydrate (MgCO3·xH2O) transformed to flake-like basic magnesium carbonate [Mg5(CO3)4(OH)2·4H2O], the reaction temperature plays an important role in the preparation of flake-like basic magnesium carbonate, the preparation of flake-like basic magnesium carbonate was a nucleation-dissolution-recrystallization growth mechanism process.
基金supported by National Key R&D Program of China(2021YFA1502803)the National Natural Science Foundation of China(NSFC)(21972066 and 91745202)+3 种基金NSFC-Royal Society Joint Program(21661130149)Luming Peng thanks the Royal Society and Newton Fund for a Royal Society-Newton Advanced Fellowshipsupported by the Research Funds for the Frontiers Science Center for Critical Earth Material Cycling,Nanjing Universitya Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions.
文摘Layered double hydroxides(LDHs)have received extensive attention in many fields such as catalysis,environmental management and medical applications.Typically,expensive soluble metal salts are commonly used as the starting materials for the synthesis of LDHs.Here,we report a novel synthesis route for Mg/Al-LDH by using inexpensive basic magnesium carbonate as the starting material.X-ray diffraction(XRD)and solid-state nuclear magnetic resonance(ssNMR)data show that LDHs with rich defects are formed rapidly at room temperature and good crystallinity can be obtained after further hydrothermal treatment.These results provide a simple,rapid and green preparation method for LDHs.
基金supported by the National Natural Science Foundation of China(No.21206191)the Science Foundation of China University of Petroleum,Beijing(No.2462013YXBS007)
文摘Basic magnesium carbonate microspheres with a red blood cell （RBC）-like appearance and diameters of ~3μm were synthesized by amphiphilic molecule-participated self-assembly under hydrothermal conditions, In the self-assembly, sodium dodecyl benzene sulfonate served as a template for the formation of Mg（OH）2 spherical micelles and also as a reactant precursor that releases CO2 to react with Mg（OH）2. The growth of the microspheres is driven by the continuous generation of new hydrophobic centers because of the consumption of hydrophilic poles （--SO3-）. The surfactant-directed self-assembly can be applied to the synthesis of other carbonate or metallic oxide self-assemblies, indicating that it is a universal self-assembly method for amphiphilic molecules.
基金supported by Special Funds for Central Public Welfare Scientific Research Institutes(K-JBYWF-2017-T06)Tianjin Science and Technology Supports Key Projects(18YFZCSF00350)。
文摘Basic magnesium carbonate(4 MgCO3·Mg(OH)2·4 H2 O) with spherical-like structure was synthesized through precursors thermal decomposition. The precursor of magnesium carbonate trihydrates(MgCO3·3 H2 O) was synthesized by brine and ammonium bicarbonate, and the thermal decomposition conditions were investigated in detail. The obtained particulate was characterized using SEM, XRD and laser particle analyzer. The result showed that it was easy to obtain spherical-like 4 MgCO3·Mg(OH)2·4 H2 O by precursor thermal decomposition at 80~100 ℃ with thermal decomposition time 90 min, stirring time 15 min and the liquid initial concentration 0.1 mol/L, while rod-like 4 MgCO3·Mg(OH)2·4 H2 O with a surface of "house of card" structure was more likely to be obtained at low temperature(55 ℃), and rosette-like products were obtained at a little higher temperature(80 ℃) by direct synthesis.
