In our modern world, where conserving energy is highly valued, thermal insulation panels play a crucial role in reducing heat transfer between two spaces, surfaces, or materials. They are used to enhance the energy ef...In our modern world, where conserving energy is highly valued, thermal insulation panels play a crucial role in reducing heat transfer between two spaces, surfaces, or materials. They are used to enhance the energy efficiency of various industrial applications by minimizing heat loss and temperature control. These panels function as silent protectors, aiding in reducing energy consumption and making things more sustainable and better for the environment. This is where composite materials come in;they are known for their lightweight nature, high strength-to-weight ratio, and excellent thermal insulation properties and have gained significant attention. Researchers are actively engaged in various studies aimed at enhancing these materials further. This research project focuses on the development of kaolin and glass fiber-reinforced composites for thermally insulating panels, to which natural strengthening materials like corn husk and bamboo fibers are added. The aim is to create cost-effective and efficient composite materials for thermal insulation applications by incorporating these components with a binder consisting of potassium silicate, hydroxide, and distilled water. This project involves conducting compression tests, bending tests, impact tests, thermal conductivity measurements, and microscopic analysis to evaluate the mechanical and thermal properties of the developed composites. The profound impact of these engineered composites on thermal insulation panels stands to revolutionize energy conservation efforts, offering a potent avenue to minimize heat loss and enhance overall energy efficiency across an array of industrial sectors.展开更多
This work describes the development of a process to produce zeolite X from mined kaolin clay from Kono-Boue and Chokocho, Rivers State, Nigeria. The procedures involved the beneficiation of the raw kaolin and calcinat...This work describes the development of a process to produce zeolite X from mined kaolin clay from Kono-Boue and Chokocho, Rivers State, Nigeria. The procedures involved the beneficiation of the raw kaolin and calcinations at 850<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">°</span>C, to transform the kaolin to a more reactive metakaolin. Afterwards, the extremely reactive metakaolin was purge with sulphuric acid to obtain the much needed silica-alumina ratio for zeolite X synthesis. An alkaline fusion stage was then carried out to transform the metakaolin into zeolite by mixing with aqueous NaOH to form gel then allowed to stay for a duration of seven days at room temperature. The samples were then charged into a propylene container and placed in an oven at a temperature of 100<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">°</span>C for the reaction to take place for 6 h. Identification of the crystalline phases by X-ray Diffraction (XRD), chemical/elemental compositions by X-ray Fluorescence (XRF)/Energy Dispersive Spectroscopic analyses (EDS), surface morphology by Scanning Electron Microscopy (SEM) and molecular vibration of units by Fourier Transform Infrared Spectrophotometry (FT-IR) were done. The results showed that the zeolite synthesized from Chokocho kaolin (CK) was more crystalline/larger with sharper peaks on both XRD and FTIR than that from Kono-Boue. This was also supported by slightly rougher surface morphology of CK over KK on SEM. XRF Si:Al ratios of 10.73 and 14.36 were obtained for KK and CK respectively. EDS results supported the XRF ratios. Sharper zeolitic characteristic O-H stretching bands at 3488 and 3755 cm<sup>-1</sup> were recorded for CK than KK. However, both results showed that zeolite X have been produced from both Kono-Boue and Chokocho kaolin clays respectively.展开更多
The structural and thermomechanical properties of starch-based plastic films reinforced with kaolin and metakaolin have been studied by various techniques (X-ray diffraction, IR-TF spectroscopy, scanning electron micr...The structural and thermomechanical properties of starch-based plastic films reinforced with kaolin and metakaolin have been studied by various techniques (X-ray diffraction, IR-TF spectroscopy, scanning electron microscopy, tensile tests, and thermal resistance). The results obtained showed that kaolin, an inert material, prevents the starch from losing its granular structure and to solubilize during the heating, generating plastic films of low Young’s modulus (7 MPa). On the other hand, metakaolin, an amorphous and dehydroxylated material obtained after heating of kaolin at 700°C for 1 hour, substantially improves the thermomechanical properties of the plastic films. The Young’s modulus increases from 19 MPa to 25 MPa while the thermal resistance increases from 90°C to 120°C. This was attributed to good dispersion of the metakaolin in the polymer matrix after the loss of the granular structure of the starch during heating.展开更多
This article reports studies on the coagulation of kaolin(from Wuxian,Jiangsu,China)on various red tide organisms,and the observation for the first time that the coagulation of kaolin is much greaterthan that of montm...This article reports studies on the coagulation of kaolin(from Wuxian,Jiangsu,China)on various red tide organisms,and the observation for the first time that the coagulation of kaolin is much greaterthan that of montmorillonite so that kaolin is a more effective clay for removing red tide organisms.The authors’theoretical explanation and analysis by a mathematical-physical model prove that comparedto montmorillonite,kaolin has greater attraction for organism cells and therefore greater coagulation capabil-ity.This project’s studies on the effects of pH and acid-treatment show that the acid-treatment does not have much influence on the kaolin system;whereas the effect of pH on the kaolin system is the same asthat on the montmonrillonite system.展开更多
Polypropylene was cracked thermally and catalytically in the presence of kaoline and silica alumina in a semi batch reactor in the temperature range 400℃～550℃ in order to obtain suitable liquid fuels.The dependenci...Polypropylene was cracked thermally and catalytically in the presence of kaoline and silica alumina in a semi batch reactor in the temperature range 400℃～550℃ in order to obtain suitable liquid fuels.The dependencies between process temperatures,types of catalyst,feed compositions and product yields of the obtained fuel fractions were found.It was observed that up to 450℃ thermal cracking temperature,the major product of pyrolysis was liquid oil and the major product at other higher temperatures(475℃～550℃) are viscous liquid or wax and the highest yield of pyrolysis product is 82.85% by weight at 500℃.Use of kaoline and silica alumina decreased the reaction time and increased the yield of liquid fraction.Again the major pyrolysis product in catalytic pyrolysis at all temperatures was low viscous liquid oil.Silica alumina was found better as compared to kaoline in liquid yield and in reducing the reaction temperature.The maximum oil yield using silica alumina and kaoline catalyst are 91% and 89.5% respectively.On the basis of the obtained results hypothetical continuous process of waste polypropylene plastics processing for engine fuel production can be presented.展开更多
Water soluble cores(WSCs) have been widely applied in manufacture of complex metal components with hollow configurations or internal channels. However, the WSCs without any additons have low tensile strength and low h...Water soluble cores(WSCs) have been widely applied in manufacture of complex metal components with hollow configurations or internal channels. However, the WSCs without any additons have low tensile strength and low humidity resistance. The purpose of this study is to prepare a water-soluble potassium carbonate sand core with addition of kaolin by the hot-temping method. The effects of kaolin on tensile strength, humidity resistance, fracture mechanism, as well as the gas evolution and collapsibility of WSCs were investigated. Results show that both the crystal morphology and the fracture mechanism of the inorganic salt are changed under the participation of kaolin, contributing to the increase of the tensile strength and the humidity resistance of the core. With the addition of 3wt.% kaolin, the tensile strength could be increased by a factor of 2, reached 1.50 MPa and the hygroscopic rate could be decreased by 14%, achieved 0.559%(after stored for 8 h), respectively. As the addition amount of kaolin increases from 0wt.% to 3wt.%, the main fracture mechanism changes from a adhesive to a cohesive fracture mechanism. The water-soluble potassium carbonate core obtained has the low gas evolution and excellent collapsibility, which makes it suitable for casting low melting metal with complex cavities and crooked channels.展开更多
Engineering property of kaolin clay contaminated by diesel oil was studied through a series of laboratory experiments.Oil contents(mass fraction) of 4%,8%,12%,16% and 20% were selected to represent different contamina...Engineering property of kaolin clay contaminated by diesel oil was studied through a series of laboratory experiments.Oil contents(mass fraction) of 4%,8%,12%,16% and 20% were selected to represent different contamination degrees,and the soil specimens were manually prepared through mixing and static compaction method.Initial water content and dry density of the test kaolin clay were controlled at 10% and 1.58 g/cm^3,respectively.Test results indicate that since part of the diesel oil will be released from soil by evaporation,the real water content should be derived through calibration of the quasi water content obtained by traditional test method.As contamination degree of the kaolin clay increases,both liquid limit and plastic limit decrease,but there's only a slight increase for plasticity index.Swelling pressure of contaminated kaolin clay under confined condition will be lowered when oil-content gets higher.Unconfined compressive strength(UCS) of the oil-contaminated kaolin clay is influenced by not only oil content but also curing period.Increase of contamination degree will continually lower UCS of the kaolin clay specimen.In addition,electrical resistivity of the contaminated kaolin clay with given water content decreases with the increase of oil content.However,soil resistivity is in good relationship with oil content and UCS.Finally,oil content of 8% is found to be a critical value for engineering property of kaolin clay to transit from water-dominated towards oil-dominated characteristics.展开更多
Kaolin as a raw material for mesoporous support was firstly modified by calcination,acid treatment,and then was used to prepare nickel catalysts.The amount of alumina which was activated in kaolin during thermal treat...Kaolin as a raw material for mesoporous support was firstly modified by calcination,acid treatment,and then was used to prepare nickel catalysts.The amount of alumina which was activated in kaolin during thermal treatment and then leached out in the acid was different.XRD pattern of the kaolin calcined at 600°C or 900°C exhibited only the diffraction peaks for amorphous silica and quartz while that calcined at 1100°C showed obvious peaks forγ-Al2 O3.Therefore,the nickel-based catalysts exhibited different physic-chemical properties.Atmospheric syngas methanation over the catalysts clarified an activity order of CA-1100 N CA-900 N CA-1400 N CA-600 N KA≈0 at temperatures of 350–650°C and a space velocity of 120 L·g-1·h-1.Metallic nickel with small diameter which has medium interaction with the modified kaolin and is well dispersed on the support would have reasonably good activity and carbon-resistance for syngas methanation.展开更多
This paper has provided an effective method to utilize the filter residue. A Y zeolite-containing composite and a fluid catalytic cracking(FCC) catalyst had been successfully prepared by an in-situ crystallization tec...This paper has provided an effective method to utilize the filter residue. A Y zeolite-containing composite and a fluid catalytic cracking(FCC) catalyst had been successfully prepared by an in-situ crystallization technology using filter residue and kaolin as raw materials. The samples were characterized by XRD, FT-IR, SEM, and N_2 adsorption-desorption techniques and evaluated in a bench FCC unit. In comparison to the reference samples synthesized from single kaolin,the silica/alumina molar ratio, the external surface area, and the total pore volume of the composite increased by 16.2%,14.5%, and 16.2%, respectively. The catalyst possessed more meso-and macro-pores and more acid sites than the reference catalyst, and exhibited better coke selectivity. The prepared catalyst had the optimum isomerization and aromatization performance. The olefin content in the cracked gasoline obtained over this catalyst was reduced by 5.05 percentage points with the research octane number of gasoline increased by 0.5 units.展开更多
Dry separation of iron mineral from low-grade coal-series kaolin in Hubei Province of China was investigated. The structure and chemical composition of the kaolin ore were determined by X-ray diffraction(XRD) and X-ra...Dry separation of iron mineral from low-grade coal-series kaolin in Hubei Province of China was investigated. The structure and chemical composition of the kaolin ore were determined by X-ray diffraction(XRD) and X-ray Fluorescence(XRF) analyses. The narrow particle size range classification, dry magnetic separation and calcination were carried out to evaluate the particle size distribution, and the relation between the content of iron and the whiteness. Experimental results revealed that the highest content of iron(3.70%) in kaolin ore was in the particle size range from 60 to 74 μm, and pyrite was the main occurrence of iron in the kaolin ore. Dry magnetic separation showed that the removal rate of iron in kaolin ore could be increased obviously after calcination, and the rate of iron removal was 60% in the particle size range from 60 to 74 μm. As pyrite can be transformed into hematite through calcination, thermodynamic studies and XRD analysis showed that the maximum content of hematite was obtained at 900 ℃, which would be more beneficial to magnetic separation.展开更多
Novel cellulose based flocculants C-g-P(DMC) with various chain architectures are synthesized through a situ graft copolymerization. The cationic ammonium chloride group(DMC) is grafted onto cellulose by two separate ...Novel cellulose based flocculants C-g-P(DMC) with various chain architectures are synthesized through a situ graft copolymerization. The cationic ammonium chloride group(DMC) is grafted onto cellulose by two separate inverse emulsion polymerization with γ-methacryloxypropyl trimethoxy silane(KH-570) and double bond addition reactions, which is a new and simple method to employ KH-570 as a bridge for the connection of cellulose matrix and DMC group. The effects of pH, flocculant dose, standing time on turbidity of kaolin suspensions and particle sizes have been studied systematically. In addition, the response surface methodology(RSM) study confirms that PAC and C-g-P(DMC)have synergy in turbidity removal with a higher removal efficiency of 98.32%. Moreover, C-g-P(DMC) 1 has higher removal efficiency with 96.5% at a low dosage of 0.6 mg L^(-1) and better floc properties than C-g-P(DMC) 2 and C-g-P(DMC) 3, suggesting that the length and quantity of cationic branch chains play a crucial role in Kaolin flocculation due to their dramatically enhanced bridging effects.展开更多
The Hizeh-Jan kaolin deposit(northwest of Varzeghan, East-Azarbaidjan Province, NW Iran) is a product of the alteration of Eocene andesitic rocks. Based on mineralogical examinations, kaolinite, quartz, smectite, pyro...The Hizeh-Jan kaolin deposit(northwest of Varzeghan, East-Azarbaidjan Province, NW Iran) is a product of the alteration of Eocene andesitic rocks. Based on mineralogical examinations, kaolinite, quartz, smectite, pyrophyllite, muscovite-illite, alunite, calcite, diaspore, goethite and hematite are the most abundant mineral phases in this deposit. The geochemical indicators, such as Y/Ho and Zr/Hf, indicate the non-CHARAC(non-Charge-radius control) behavior of these pairs, which are likely to be due to the occurrence of the tetrad effect phenomenon in this deposit. Simultaneous concave and convex shapes in the chondrite-normalized REE distribution patterns are a remarkable feature of the kaolin samples. Bivariate diagrams of the size of the third tetrad effect(T_3) versus geochemical parameters such as Y/Ho, Nb/Ta and Zr/Hf ratios display two distinct populations for the kaolin samples. The first population is characterized by high T_3 values(>0.13), which are near or on the fault zone. The second population is characterized by low T_3 values(<0.13), and are farther from the fault zone. The obtained results from the geochemical data have furnished compelling evidence that fluidrock interaction, overprint of hypogene processes by supergene ones, and structural control, are key controlling factors for the occurrence of tetrad effects in REE distribution patterns in the Hizeh-Jan kaolin deposit.展开更多
The influence of replacement level of calcined coal-series kaolin (CCK) on hydration of ordinary Portland cement (OPC) was studied by X-ray diffraction(XRD)/Rietveld method. X-ray diffraction/ Rietveld method was used...The influence of replacement level of calcined coal-series kaolin (CCK) on hydration of ordinary Portland cement (OPC) was studied by X-ray diffraction(XRD)/Rietveld method. X-ray diffraction/ Rietveld method was used to quantify the crystalline phase composition of the hydrated samples. Additionally, the morphology of hydrated samples was observed by scanning electron microscopy (SEM). The results showed that, calcium hydroxide (CH), ettringite (AFt) and amorphous phase content in hydrated samples decreased as the replacement level of CCK increased, while AFm and stratiingite increased, which was caused by the combination of dilute, physical and pozzolanic effects. The hydration of anhydrous cement phases was accelerated by physical effect but hindered by the retardation effect of CCK. The role of each effects was discussed in detail to analyze the mechanism of OPC hydration with CCK addition. The SEM images showed that the shortening of AFt at 1 day and the denser texture at 28 days was observed with CCK addition, which was caused by the physical and pozzolanic effects, respectively.展开更多
The Algerian kaolin clay was investigated to remove Zn(II) heavy metal ion from aqueous solution. The effect of contact time, initial metal ion concentration, pH and temperature was experimentally studied in batch mod...The Algerian kaolin clay was investigated to remove Zn(II) heavy metal ion from aqueous solution. The effect of contact time, initial metal ion concentration, pH and temperature was experimentally studied in batch mode to evaluate the adsorption capacity, kinetic, thermodynamic and equilibrium. The extent of zinc adsorption increased with increasing initial concentration of adsorbat, pH and temperature. The linear Langmuir and Freundlich models were applied to describe equilibrium isotherms and both models fitted well. The monolayer adsorption capacity for Zn(II) ions was 12.23 mg per g of kaolin clay at pH 6.1 and 25°C. Dubinin-Radushkevich (D-R) isotherm model was also applied to the equilibrium data. Thermodynamic parameters showed that the adsorption of Zn(II) onto kaolin clay was spontaneous and endothermic process in nature. Furthermore, the Lagergren-first-order and pseudo-second-order models were used to describe the kinetic data. The experimental data fitted well the pseudo-second-order kinetic. As a result, the kaolin clay may be used for removal of zinc from aqueous media.展开更多
The resistance of wood-fiber paper to water, grease, and water vapor is usually attained by immersing the base paper in hydrophobic oil, laminating with a plastic or metal film, or the application of a barrier coating...The resistance of wood-fiber paper to water, grease, and water vapor is usually attained by immersing the base paper in hydrophobic oil, laminating with a plastic or metal film, or the application of a barrier coating. Oil impregnation and the addition of films may make the paper difficult to recycle or persistent in the environment owing to their strong binding force and nondegradability. Environmental concerns have attracted worldwide attention to eco-friendly barrier coatings. In this study, degradable polyvinyl alcohol(PVA) and kaolin clay pigment were used to prepare coatings that were applied to a base paper. By measuring the barrier properties of the coated paper, including the water absorptiveness(Cobb60 value), Hercules sizing degree, oil resistance(Kit rating), and water vapor transmission rate(WVTR), an optimal coating formulation and process were proposed. To examine the barrier mechanism of the PVA/kaolin clay coating, we characterized the coating microstructures using a scanning electron microscopy(SEM) and a mercury porosimeter. The results showed that the Cobb60 value and water vapor transmission rate of the coated paper decreased by 61.4% and 98.6%, respectively, compared with the base paper, for a pre-coating weight of 0.98 g/m^2 and a top-coating weight of about 3.23 g/m^2. Furthermore, the Hercules sizing degree rose by a factor of 337.2, while the oil resistance(Kit rating) increased from 0 to 12. The optimum drying temperature for a wet coating layer was found to be 170℃, and the optimum weight ratio of PVA to kaolin clay in the coating was determined to be 50∶50. It was assumed that the PVA/kaolin clay coating improved the smoothness of the paper considerably and decreased the pore size by filling the pores on the paper surface and forming an even film, thus enhancing the paper barrier performance. The coated paper also exhibited good repulpability.展开更多
文摘In our modern world, where conserving energy is highly valued, thermal insulation panels play a crucial role in reducing heat transfer between two spaces, surfaces, or materials. They are used to enhance the energy efficiency of various industrial applications by minimizing heat loss and temperature control. These panels function as silent protectors, aiding in reducing energy consumption and making things more sustainable and better for the environment. This is where composite materials come in;they are known for their lightweight nature, high strength-to-weight ratio, and excellent thermal insulation properties and have gained significant attention. Researchers are actively engaged in various studies aimed at enhancing these materials further. This research project focuses on the development of kaolin and glass fiber-reinforced composites for thermally insulating panels, to which natural strengthening materials like corn husk and bamboo fibers are added. The aim is to create cost-effective and efficient composite materials for thermal insulation applications by incorporating these components with a binder consisting of potassium silicate, hydroxide, and distilled water. This project involves conducting compression tests, bending tests, impact tests, thermal conductivity measurements, and microscopic analysis to evaluate the mechanical and thermal properties of the developed composites. The profound impact of these engineered composites on thermal insulation panels stands to revolutionize energy conservation efforts, offering a potent avenue to minimize heat loss and enhance overall energy efficiency across an array of industrial sectors.
文摘This work describes the development of a process to produce zeolite X from mined kaolin clay from Kono-Boue and Chokocho, Rivers State, Nigeria. The procedures involved the beneficiation of the raw kaolin and calcinations at 850<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">°</span>C, to transform the kaolin to a more reactive metakaolin. Afterwards, the extremely reactive metakaolin was purge with sulphuric acid to obtain the much needed silica-alumina ratio for zeolite X synthesis. An alkaline fusion stage was then carried out to transform the metakaolin into zeolite by mixing with aqueous NaOH to form gel then allowed to stay for a duration of seven days at room temperature. The samples were then charged into a propylene container and placed in an oven at a temperature of 100<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">°</span>C for the reaction to take place for 6 h. Identification of the crystalline phases by X-ray Diffraction (XRD), chemical/elemental compositions by X-ray Fluorescence (XRF)/Energy Dispersive Spectroscopic analyses (EDS), surface morphology by Scanning Electron Microscopy (SEM) and molecular vibration of units by Fourier Transform Infrared Spectrophotometry (FT-IR) were done. The results showed that the zeolite synthesized from Chokocho kaolin (CK) was more crystalline/larger with sharper peaks on both XRD and FTIR than that from Kono-Boue. This was also supported by slightly rougher surface morphology of CK over KK on SEM. XRF Si:Al ratios of 10.73 and 14.36 were obtained for KK and CK respectively. EDS results supported the XRF ratios. Sharper zeolitic characteristic O-H stretching bands at 3488 and 3755 cm<sup>-1</sup> were recorded for CK than KK. However, both results showed that zeolite X have been produced from both Kono-Boue and Chokocho kaolin clays respectively.
文摘The structural and thermomechanical properties of starch-based plastic films reinforced with kaolin and metakaolin have been studied by various techniques (X-ray diffraction, IR-TF spectroscopy, scanning electron microscopy, tensile tests, and thermal resistance). The results obtained showed that kaolin, an inert material, prevents the starch from losing its granular structure and to solubilize during the heating, generating plastic films of low Young’s modulus (7 MPa). On the other hand, metakaolin, an amorphous and dehydroxylated material obtained after heating of kaolin at 700°C for 1 hour, substantially improves the thermomechanical properties of the plastic films. The Young’s modulus increases from 19 MPa to 25 MPa while the thermal resistance increases from 90°C to 120°C. This was attributed to good dispersion of the metakaolin in the polymer matrix after the loss of the granular structure of the starch during heating.
基金Project supported by Chinese Possteoctoral Fund Shandong Natural Science Fund No.93E0175
文摘This article reports studies on the coagulation of kaolin(from Wuxian,Jiangsu,China)on various red tide organisms,and the observation for the first time that the coagulation of kaolin is much greaterthan that of montmorillonite so that kaolin is a more effective clay for removing red tide organisms.The authors’theoretical explanation and analysis by a mathematical-physical model prove that comparedto montmorillonite,kaolin has greater attraction for organism cells and therefore greater coagulation capabil-ity.This project’s studies on the effects of pH and acid-treatment show that the acid-treatment does not have much influence on the kaolin system;whereas the effect of pH on the kaolin system is the same asthat on the montmonrillonite system.
文摘Polypropylene was cracked thermally and catalytically in the presence of kaoline and silica alumina in a semi batch reactor in the temperature range 400℃～550℃ in order to obtain suitable liquid fuels.The dependencies between process temperatures,types of catalyst,feed compositions and product yields of the obtained fuel fractions were found.It was observed that up to 450℃ thermal cracking temperature,the major product of pyrolysis was liquid oil and the major product at other higher temperatures(475℃～550℃) are viscous liquid or wax and the highest yield of pyrolysis product is 82.85% by weight at 500℃.Use of kaoline and silica alumina decreased the reaction time and increased the yield of liquid fraction.Again the major pyrolysis product in catalytic pyrolysis at all temperatures was low viscous liquid oil.Silica alumina was found better as compared to kaoline in liquid yield and in reducing the reaction temperature.The maximum oil yield using silica alumina and kaoline catalyst are 91% and 89.5% respectively.On the basis of the obtained results hypothetical continuous process of waste polypropylene plastics processing for engine fuel production can be presented.
基金supported by the National Natural Science Foundation of China(No.51405002)
文摘Water soluble cores(WSCs) have been widely applied in manufacture of complex metal components with hollow configurations or internal channels. However, the WSCs without any additons have low tensile strength and low humidity resistance. The purpose of this study is to prepare a water-soluble potassium carbonate sand core with addition of kaolin by the hot-temping method. The effects of kaolin on tensile strength, humidity resistance, fracture mechanism, as well as the gas evolution and collapsibility of WSCs were investigated. Results show that both the crystal morphology and the fracture mechanism of the inorganic salt are changed under the participation of kaolin, contributing to the increase of the tensile strength and the humidity resistance of the core. With the addition of 3wt.% kaolin, the tensile strength could be increased by a factor of 2, reached 1.50 MPa and the hygroscopic rate could be decreased by 14%, achieved 0.559%(after stored for 8 h), respectively. As the addition amount of kaolin increases from 0wt.% to 3wt.%, the main fracture mechanism changes from a adhesive to a cohesive fracture mechanism. The water-soluble potassium carbonate core obtained has the low gas evolution and excellent collapsibility, which makes it suitable for casting low melting metal with complex cavities and crooked channels.
基金Projects(41330641,41272311,41202192)supported by the National Natural Science Foundation of ChinaProject(BK2010060)supported by the Key Project of Natural Science Foundation of Jiangsu Province,China
文摘Engineering property of kaolin clay contaminated by diesel oil was studied through a series of laboratory experiments.Oil contents(mass fraction) of 4%,8%,12%,16% and 20% were selected to represent different contamination degrees,and the soil specimens were manually prepared through mixing and static compaction method.Initial water content and dry density of the test kaolin clay were controlled at 10% and 1.58 g/cm^3,respectively.Test results indicate that since part of the diesel oil will be released from soil by evaporation,the real water content should be derived through calibration of the quasi water content obtained by traditional test method.As contamination degree of the kaolin clay increases,both liquid limit and plastic limit decrease,but there's only a slight increase for plasticity index.Swelling pressure of contaminated kaolin clay under confined condition will be lowered when oil-content gets higher.Unconfined compressive strength(UCS) of the oil-contaminated kaolin clay is influenced by not only oil content but also curing period.Increase of contamination degree will continually lower UCS of the kaolin clay specimen.In addition,electrical resistivity of the contaminated kaolin clay with given water content decreases with the increase of oil content.However,soil resistivity is in good relationship with oil content and UCS.Finally,oil content of 8% is found to be a critical value for engineering property of kaolin clay to transit from water-dominated towards oil-dominated characteristics.
基金Supported by the National Natural Science Foundation of China(21161140329)the National High Technology Research and Development Program of China(2015AA050502).
文摘Kaolin as a raw material for mesoporous support was firstly modified by calcination,acid treatment,and then was used to prepare nickel catalysts.The amount of alumina which was activated in kaolin during thermal treatment and then leached out in the acid was different.XRD pattern of the kaolin calcined at 600°C or 900°C exhibited only the diffraction peaks for amorphous silica and quartz while that calcined at 1100°C showed obvious peaks forγ-Al2 O3.Therefore,the nickel-based catalysts exhibited different physic-chemical properties.Atmospheric syngas methanation over the catalysts clarified an activity order of CA-1100 N CA-900 N CA-1400 N CA-600 N KA≈0 at temperatures of 350–650°C and a space velocity of 120 L·g-1·h-1.Metallic nickel with small diameter which has medium interaction with the modified kaolin and is well dispersed on the support would have reasonably good activity and carbon-resistance for syngas methanation.
基金financially supported by the National Natural Science Foundation of China (No.21371055)the Hunan Provincial Colleges and Universities Innovation Platform Open Fund Project (No.15K049)
文摘This paper has provided an effective method to utilize the filter residue. A Y zeolite-containing composite and a fluid catalytic cracking(FCC) catalyst had been successfully prepared by an in-situ crystallization technology using filter residue and kaolin as raw materials. The samples were characterized by XRD, FT-IR, SEM, and N_2 adsorption-desorption techniques and evaluated in a bench FCC unit. In comparison to the reference samples synthesized from single kaolin,the silica/alumina molar ratio, the external surface area, and the total pore volume of the composite increased by 16.2%,14.5%, and 16.2%, respectively. The catalyst possessed more meso-and macro-pores and more acid sites than the reference catalyst, and exhibited better coke selectivity. The prepared catalyst had the optimum isomerization and aromatization performance. The olefin content in the cracked gasoline obtained over this catalyst was reduced by 5.05 percentage points with the research octane number of gasoline increased by 0.5 units.
基金Funded by the Academician Workstation of Yichang Hui Long Science and Technology Co.Ltd.Association of Science and Technology of Hubei Province(No.[2013]104-22)
文摘Dry separation of iron mineral from low-grade coal-series kaolin in Hubei Province of China was investigated. The structure and chemical composition of the kaolin ore were determined by X-ray diffraction(XRD) and X-ray Fluorescence(XRF) analyses. The narrow particle size range classification, dry magnetic separation and calcination were carried out to evaluate the particle size distribution, and the relation between the content of iron and the whiteness. Experimental results revealed that the highest content of iron(3.70%) in kaolin ore was in the particle size range from 60 to 74 μm, and pyrite was the main occurrence of iron in the kaolin ore. Dry magnetic separation showed that the removal rate of iron in kaolin ore could be increased obviously after calcination, and the rate of iron removal was 60% in the particle size range from 60 to 74 μm. As pyrite can be transformed into hematite through calcination, thermodynamic studies and XRD analysis showed that the maximum content of hematite was obtained at 900 ℃, which would be more beneficial to magnetic separation.
基金supported by the National Natural Science Foundation of China (51379077,21607044)the Fundamental Research Funds for the Central Universities (2016MS108)Natural Science Foundation of Hebei Province (B2017502069)
文摘Novel cellulose based flocculants C-g-P(DMC) with various chain architectures are synthesized through a situ graft copolymerization. The cationic ammonium chloride group(DMC) is grafted onto cellulose by two separate inverse emulsion polymerization with γ-methacryloxypropyl trimethoxy silane(KH-570) and double bond addition reactions, which is a new and simple method to employ KH-570 as a bridge for the connection of cellulose matrix and DMC group. The effects of pH, flocculant dose, standing time on turbidity of kaolin suspensions and particle sizes have been studied systematically. In addition, the response surface methodology(RSM) study confirms that PAC and C-g-P(DMC)have synergy in turbidity removal with a higher removal efficiency of 98.32%. Moreover, C-g-P(DMC) 1 has higher removal efficiency with 96.5% at a low dosage of 0.6 mg L^(-1) and better floc properties than C-g-P(DMC) 2 and C-g-P(DMC) 3, suggesting that the length and quantity of cationic branch chains play a crucial role in Kaolin flocculation due to their dramatically enhanced bridging effects.
基金supported financially by the Research Bureau of Urmia University
文摘The Hizeh-Jan kaolin deposit(northwest of Varzeghan, East-Azarbaidjan Province, NW Iran) is a product of the alteration of Eocene andesitic rocks. Based on mineralogical examinations, kaolinite, quartz, smectite, pyrophyllite, muscovite-illite, alunite, calcite, diaspore, goethite and hematite are the most abundant mineral phases in this deposit. The geochemical indicators, such as Y/Ho and Zr/Hf, indicate the non-CHARAC(non-Charge-radius control) behavior of these pairs, which are likely to be due to the occurrence of the tetrad effect phenomenon in this deposit. Simultaneous concave and convex shapes in the chondrite-normalized REE distribution patterns are a remarkable feature of the kaolin samples. Bivariate diagrams of the size of the third tetrad effect(T_3) versus geochemical parameters such as Y/Ho, Nb/Ta and Zr/Hf ratios display two distinct populations for the kaolin samples. The first population is characterized by high T_3 values(>0.13), which are near or on the fault zone. The second population is characterized by low T_3 values(<0.13), and are farther from the fault zone. The obtained results from the geochemical data have furnished compelling evidence that fluidrock interaction, overprint of hypogene processes by supergene ones, and structural control, are key controlling factors for the occurrence of tetrad effects in REE distribution patterns in the Hizeh-Jan kaolin deposit.
基金Funded by the Academician Workstation of Yichang Huilong Science and Technology Co.,Ltd.Association of Science and Technology of Hubei Province(No.2013]104-22)
文摘The influence of replacement level of calcined coal-series kaolin (CCK) on hydration of ordinary Portland cement (OPC) was studied by X-ray diffraction(XRD)/Rietveld method. X-ray diffraction/ Rietveld method was used to quantify the crystalline phase composition of the hydrated samples. Additionally, the morphology of hydrated samples was observed by scanning electron microscopy (SEM). The results showed that, calcium hydroxide (CH), ettringite (AFt) and amorphous phase content in hydrated samples decreased as the replacement level of CCK increased, while AFm and stratiingite increased, which was caused by the combination of dilute, physical and pozzolanic effects. The hydration of anhydrous cement phases was accelerated by physical effect but hindered by the retardation effect of CCK. The role of each effects was discussed in detail to analyze the mechanism of OPC hydration with CCK addition. The SEM images showed that the shortening of AFt at 1 day and the denser texture at 28 days was observed with CCK addition, which was caused by the physical and pozzolanic effects, respectively.
文摘The Algerian kaolin clay was investigated to remove Zn(II) heavy metal ion from aqueous solution. The effect of contact time, initial metal ion concentration, pH and temperature was experimentally studied in batch mode to evaluate the adsorption capacity, kinetic, thermodynamic and equilibrium. The extent of zinc adsorption increased with increasing initial concentration of adsorbat, pH and temperature. The linear Langmuir and Freundlich models were applied to describe equilibrium isotherms and both models fitted well. The monolayer adsorption capacity for Zn(II) ions was 12.23 mg per g of kaolin clay at pH 6.1 and 25°C. Dubinin-Radushkevich (D-R) isotherm model was also applied to the equilibrium data. Thermodynamic parameters showed that the adsorption of Zn(II) onto kaolin clay was spontaneous and endothermic process in nature. Furthermore, the Lagergren-first-order and pseudo-second-order models were used to describe the kinetic data. The experimental data fitted well the pseudo-second-order kinetic. As a result, the kaolin clay may be used for removal of zinc from aqueous media.
基金financially supported by the National Natural Science Foundation of China (Grant number:51403239)
文摘The resistance of wood-fiber paper to water, grease, and water vapor is usually attained by immersing the base paper in hydrophobic oil, laminating with a plastic or metal film, or the application of a barrier coating. Oil impregnation and the addition of films may make the paper difficult to recycle or persistent in the environment owing to their strong binding force and nondegradability. Environmental concerns have attracted worldwide attention to eco-friendly barrier coatings. In this study, degradable polyvinyl alcohol(PVA) and kaolin clay pigment were used to prepare coatings that were applied to a base paper. By measuring the barrier properties of the coated paper, including the water absorptiveness(Cobb60 value), Hercules sizing degree, oil resistance(Kit rating), and water vapor transmission rate(WVTR), an optimal coating formulation and process were proposed. To examine the barrier mechanism of the PVA/kaolin clay coating, we characterized the coating microstructures using a scanning electron microscopy(SEM) and a mercury porosimeter. The results showed that the Cobb60 value and water vapor transmission rate of the coated paper decreased by 61.4% and 98.6%, respectively, compared with the base paper, for a pre-coating weight of 0.98 g/m^2 and a top-coating weight of about 3.23 g/m^2. Furthermore, the Hercules sizing degree rose by a factor of 337.2, while the oil resistance(Kit rating) increased from 0 to 12. The optimum drying temperature for a wet coating layer was found to be 170℃, and the optimum weight ratio of PVA to kaolin clay in the coating was determined to be 50∶50. It was assumed that the PVA/kaolin clay coating improved the smoothness of the paper considerably and decreased the pore size by filling the pores on the paper surface and forming an even film, thus enhancing the paper barrier performance. The coated paper also exhibited good repulpability.
