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Synthesis, characterization and assessment thermal properties of clay based nanopigments

Mohammad Banimahd KIEVANI, Milad EDRAKI

《化学科学与工程前沿（英文）》 2015年 第9卷 第1期   页码 40-45 doi: 10.1007/s11705-015-1505-7

摘要： Nano-clay based pigments (NCP) are new type of pigments composed of organic dyes and layered silicate-clay nano-particles, and have already been used in polymeric coatings to improve mechanical thermal and stability properties. In this paper, the basic blue 41(BB41) was intercalated into Na - montmorillonite in an aqueous medium. The dye-intercalated montmorillonite was centrifuged, dried, and milled to prepare the nanopigment particles. X-ray diffraction showed an increase in the basal spacing, thus confirming intercalation of the BB41 molecules within the nanostructures of the interlayer spaces. Fourier transform infrared spectroscopy was used for identifying the functional groups and chemical bounding of Na -montmorillonite, BB41 and montmorillonite-BB41. The morphology of NCP was also studied by transmission electron microscopy. Finally, thermo-gravimetric analysis and differential thermograms suggested the thermal stability of the intercalated dye was improved.

关键词： nanopigment     layered silicate     cationic dye     thermal properties    

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Effect of the degree of template removal from mesoporous silicate materials on their adsorption of heavy

Farouq TWAIQ,M.S. NASSER,Sagheer A. ONAIZI

《化学科学与工程前沿（英文）》 2014年 第8卷 第4期   页码 488-497 doi: 10.1007/s11705-014-1459-1

摘要： The key aim of this study is to evaluate the adsorption of heavy oil from aqueous solutions with different oil contents over mesoporous silicate materials having different surfactant template contents. The mesoporous silicate materials have been synthesized from tetraethylorthosilicate as a silica precursor and cetyltrimethylammonium bromide as a template using the sol-gel technique. Four samples were prepared by (1) totally removing the template using the calcination process, (2) partially removing the template via ethanol extraction, (3) partially removing the template via water extraction, and (4) keeping the template as synthesized, respectively. These four samples have been characterized using X-ray diffraction, nitrogen adsorption, thermal gravimetric analysis and Fourier transformed infrared. The effect of the degree of template removal of these mesoporous materials for the oil removal has been investigated. The oil removal is inversely proportional to the surfactant content in the mesoporous material, being highest for the calcined sample but lowest for the as-synthesized sample. The kinetic of oil adsorption over the calcined material has been also studied and the data obtained fit well a second-order model.

关键词： heavy oil     mesoporous silicate material     kinetics     template removal     adsorption    

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Capture of carbon dioxide over porous solid adsorbents lithium silicate, lithium aluminate and magnesium

P. V. Korake, A. G. Gaikwad

《化学科学与工程前沿（英文）》 2011年 第5卷 第2期   页码 215-226 doi: 10.1007/s11705-010-1012-9

摘要： The capturing process for carbon dioxide over porous solid adsorbents such as lithium silicate, lithium aluminate, and magnesium aluminate at pre- combustion temperatures was studied. Lithium silicate was prepared by the sol gel and solid fusion methods. The lithium silicate adsorbent was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), nuclear magnetic resonance (NMR), and surface area. The capturing of carbon dioxide over lithium silicate, lithium aluminate, and magnesium aluminate was explored at different experimental conditions such as exposure time, temperature variation, and exposure carbon dioxide pressure. The capturing process for carbon dioxide was investigated over these adsorbents with variation of their metal mole ratios. The effect of the addition of (promoter) sodium, potassium, and cesium in the lithium silicate adsorbent was explored to investigate the variation of the capture of carbon dioxide over these adsorbents.

关键词： capturing CO2     lithium silicate     lithium aluminate     magnesium aluminate    

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capture of carbon dioxide by transition metal aluminates, calcium aluminate, calcium zirconate, calcium silicate

Ganesh TILEKAR, Kiran SHINDE, Kishor KALE, Reshma RASKAR, Abaji GAIKWAD

《化学科学与工程前沿（英文）》 2011年 第5卷 第4期   页码 477-491 doi: 10.1007/s11705-011-1107-y

摘要： The capture of CO by transition metal (Mn, Ni, Co and Zn) aluminates, calcium aluminate, calcium zirconate, calcium silicate and lithium zirconate was carried out at pre- and post-combustion temperatures. The prepared metal adsorbents were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), surface area analysis and acidity/alkalinity measurements. The different experimental variables affecting the adsorbents ability to capture CO , such as the mol ratio of metal ions, the pressure of CO , the exposure time and the temperature of the adsorbent were also investigated. Calcium zirconate captured 13.85 wt-% CO at 650°C and 2.5 atm and calcium silicate captured 14.31 wt-% at 650°C. Molecular sieves (13X) and carbon can only capture a negligible amount of CO at high temperatures (300°C–650°C). However, the mixed metal oxides captured reasonable amount of CO at these higher temperatures. In addition, calcium aluminate, calcium zirconate, calcium silicate and lithium zirconate adsorbents captured CO at both pre and post-combustion temperatures. The trend for the amount of captured carbon dioxide over the adsorbents was calcium aluminate

关键词： captured CO2     pre-combustion temperature     characterization     calcium silicate     calcium zirconate    

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Stability analysis of layered slopes in unsaturated soils

Guangyu DAI; Fei ZHANG; Yuke WANG

《结构与土木工程前沿（英文）》 2022年 第16卷 第3期   页码 378-387 doi: 10.1007/s11709-022-0808-2

摘要： This study presents stability analyses of layered soil slopes in unsaturated conditions and uses a limit equilibrium method to determine the factor of safety involving suction stress of unsaturated soil. One-dimensional steady infiltration and evaporation conditions are considered in the stability analyses. An example of a two-layered slope in clay and silt is selected to verify the used method by comparing with the results of other methods. Parametric analyses are conducted to explore the influences of the matric suction on the stability of layered soil slopes. The obtained results show that larger suction stress provided in unsaturated clay dominates the stability of the layered slopes. Therefore, the location and thickness of the clay layer have significant influences on slope stability. As the water level decreases, the factor of safety reduces and then increases gradually in most cases. Infiltration/evaporation can obviously affect the stability of unsaturated layered slopes, but their influences depend on the soil property and thickness of the lower soil layer.

关键词： slope stability     suction stress     unsaturated soil     layered slope     limit equilibrium    

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Quantification of seepage in a multi-layered disconnected river-aquifer system

Jiang LI, Haizhu HU, Xiaomin MAO, Yi LIU

《农业科学与工程前沿（英文）》 2017年 第4卷 第2期   页码 237-245 doi: 10.15302/J-FASE-2017135

摘要： Quantification of seepage in disconnected river-aquifer systems is significant for local water management and groundwater pollution control, especially in areas with water shortage or contamination. The vadose zone under riverbeds usually exhibits a multi-layered structure, particularly when paved with low permeability liners. To evaluate the impact of engineering solutions to seepage under such conditions, we proposed an approach by combining GIS and the minimum flux in saturation layer (MFSL) method. MFSL can calculate the stable seepage rate by assessing the dominant low permeability layers (including but not limited to the liners) in multi-layered disconnected river-aquifer systems. We used MFSL to calculate local seepage rate, and used GIS to extend the results to a regional scale. The reliability of MFSL is discussed by comparing the results with the double ring infiltration test, the numerical simulation by HYDRUS, and the methods of stream package in MODFLOW, including its improved form. A case study was conducted in the Yongding River with river-aquifer seepage calculated under various conditions, including different river water levels (i.e., under the designated water level, drought stage level, flood stage level and flood inundation level) and with/without low permeability liners (i.e., ecological membranes or geomembrane). Results showed that low permeability liners could greatly reduce the seepage rate. However, if an unlined inundation area exists, the seepage rate may increase greatly. The results indicated that the proposed method was reliable and convenient for calculating long-term, large area seepage in disconnected river-aquifer systems especially those paved with liners.

关键词： infiltration     low permeability liner     multi-layered porous media     river-aquifer seepage    

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Crack evolution of soft–hard composite layered rock-like specimens with two fissures under uniaxial compression

《结构与土木工程前沿（英文）》 2021年 第15卷 第6期   页码 1372-1389 doi: 10.1007/s11709-021-0772-2

摘要： Acoustic emission and digital image correlation were used to study the spatiotemporal evolution characteristics of crack extension of soft and hard composite laminated rock masses (SHCLRM) containing double fissures under uniaxial compression. The effects of different rock combination methods and prefabricated fissures with different orientations on mechanical properties and crack coalescence patterns were analyzed. The characteristics of the acoustic emission source location distribution, and frequency changes of the crack evolution process were also investigated. The test results show that the damage mode of SHCLRM is related to the combination mode of rock layers and the orientation of fractures. Hard layers predominantly produce tensile cracks; soft layers produce shear cracks. The first crack always sprouts at the tip or middle of prefabricated fractures in hard layers. The acoustic emission signal of SHCLRM with double fractures has clear stage characteristics, and the state of crack development can be inferred from this signal to provide early warning for rock fracture instability. This study can provide a reference for the assessment of the fracture development status between adjacent roadways in SHCLRM in underground mines, as well as in roadway layout and support.

关键词： soft−hard composite layered rock mass     double cracks     crack evolution     acoustic emission     digital image correlation    

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Hierarchically porous cellulose nanofibril aerogel decorated with polypyrrole and nickel-cobalt layered

《化学科学与工程前沿（英文）》 2023年 第17卷 第10期   页码 1593-1607 doi: 10.1007/s11705-023-2348-2

摘要： With increasing emphasis on green chemistry, biomass-based materials have attracted increased attention regarding the development of highly efficient functional materials. Herein, a new pore-rich cellulose nanofibril aerogel is utilized as a substrate to integrate highly conductive polypyrrole and active nanoflower-like nickel-cobalt layered double hydroxide through in situ chemical polymerization and electrodeposition. This ternary composite can act as an effective self-supported electrode for the electrocatalytic oxidation of glucose. With the synergistic effect of three heterogeneous components, the electrode achieves outstanding glucose sensing performance, including a high sensitivity (851.4 µA·mmol−1·L·cm−2), a short response time (2.2 s), a wide linear range (two stages: 0.001−8.145 and 8.145−35.500 mmol·L−1), strong immunity to interference, outstanding intraelectrode and interelectrode reproducibility, a favorable toxicity resistance (Cl‒), and a good long-term stability (maintaining 86.0% of the original value after 30 d). These data are superior to those of some traditional glucose sensors using nonbiomass substrates. When determining the blood glucose level of a human serum, this electrode realizes a high recovery rate of 97.07%–98.89%, validating the potential for high-performance blood glucose sensing.

关键词： cellulose nanofibril     aerogel     nickel-cobalt layered double hydroxide     polypyrrole     nonenzymatic glucose sensor    

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Hydraulic fracturing pressure of concentric double-layered cylinder in cohesive soil

《结构与土木工程前沿（英文）》 2021年 第15卷 第4期   页码 937-947 doi: 10.1007/s11709-021-0754-4

摘要： This study aims to investigate hydrofracturing in double-layered soil through theoretical and experimental analysis, as multilayered soils where the difference in mechanical properties exists are generally encountered in practical engineering. First, an analytical solution for fracturing pressure in two different concentric regions of soil was presented based on the cavity expansion theory. Then, several triaxial hydraulic fracturing tests were carried out to validate the analytical solution. The comparison between the experimental and analytical results indicates the remarkable accuracy of the derived formula, and the following conclusions were also obtained. First, there is a linear relationship between the fracturing pressure and confining pressure in concentric double-layered cohesive soil. Second, when the internal-layer soil is softer than the external-layer soil, the presence of internal soil on the fracturing pressure approximately brings the weakening effect, and the greater strength distinction between the two layers, the greater the weakening effect. Third, when the internal-layer soil is harder than the external-layer soil, the existence of the internal-layer soil has a strengthening effect on the fracturing pressure regardless of the proportion of internal-layer soil. Moreover, the influence of strength distinction between the two layers on the fracturing pressure is significant when the proportion of internal-layer soil is less than half, while it’s limited when the proportion is more than half. The proposed solution is potentially useful for geotechnical problems involving aspects of cohesive soil layering in a composite formation.

关键词： hydraulic fracturing pressure     layered     cavity expansion theory     triaxial fracturing test     cohesive soil    

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Size effects in two-dimensional layered materials modeled by couple stress elasticity

Wipavee WONGVIBOONSIN, Panos GOURGIOTIS, Chung Nguyen VAN, Suchart LIMKATANYU, Jaroon RUNGAMORNRAT

《结构与土木工程前沿（英文）》 2021年 第15卷 第2期   页码 425-443 doi: 10.1007/s11709-021-0707-y

摘要： In the present study, the effect of material microstructure on the mechanical response of a two-dimensional elastic layer perfectly bonded to a substrate is examined under surface loadings. In the current model, the substrate is treated as an elastic half plane as opposed to a rigid base, and this enables its applications in practical cases when the modulus of the layer (e.g., the coating material) and substrate (e.g., the coated surface) are comparable. The material microstructure is modeled using the generalized continuum theory of couple stress elasticity. The boundary value problems are formulated in terms of the displacement field and solved in an analytical manner via the Fourier transform and stiffness matrix method. The results demonstrate the capability of the present continuum theory to efficiently model the size-dependency of the response of the material when the external and internal length scales are comparable. Furthermore, the results indicated that the material mismatch and substrate stiffness play a crucial role in the predicted elastic field. Specifically, the study also addresses significant discrepancy of the response for the case of a layer resting on a rigid substrate.

关键词： cosserat     layered materials     size effects     microstructure    

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New pseudo-dynamic analysis of two-layered cohesive-friction soil slope and its numerical validation

Suman HAZARI, Sima GHOSH, Richi Prasad SHARMA

《结构与土木工程前沿（英文）》 2020年 第14卷 第6期   页码 1492-1508 doi: 10.1007/s11709-020-0679-3

摘要： Natural slopes consist of non-homogeneous soil profiles with distinct characteristics from slopes made of homogeneous soil. In this study, the limit equilibrium modified pseudo-dynamic method is used to analyze the stability of two-layered soil slopes in which the failure surface is assumed to be a logarithmic spiral. The zero-stress boundary condition at the ground surface under the seismic loading condition is satisfied. New formulations derived from an analytical method are proposed for the predicting the seismic response in two-layered soil. A detailed parametric study was performed in which various parameters (seismic accelerations, damping, cohesion, and angle of internal friction) were varied. The results of the present method were compared with those in the available literature. The present analytical analysis was also verified against the finite element analysis results.

关键词： layered soil     limit equilibrium method     seismic analysis     damping     PLAXIS    

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Mechanical responses of multi-layered ground due to shallow tunneling with arbitrary ground surface load

《结构与土木工程前沿（英文）》 2023年 第17卷 第5期   页码 745-762 doi: 10.1007/s11709-023-0935-4

摘要： An analytical model based on complex variable theory is proposed to investigate ground responses due to shallow tunneling in multi-layered ground with an arbitrary ground surface load. The ground layers are assumed to be linear-elastic with full-stick contact between them. To solve the proposed multi-boundary problem, a series of analytic functions is introduced to accurately express the stresses and displacements contributed by different boundaries. Based on the principle of linear-elastic superposition, the multi-boundary problem is converted into a superposition of multiple single-boundary problems. The conformal mappings of different boundaries are independent of each other, which allows the stress and displacement fields to be obtained by the sum of components from each boundary. The analytical results are validated based on numerical and in situ monitoring results. The present model is superior to the classical model for analyzing ground responses of shallow tunneling in multi-layered ground; thus, it can be used with assurance to estimate the ground movement and surface building safety of shallow tunnel constructions beneath surface buildings. Moreover, the solution for the ground stress distribution can be used to estimate the safety of a single-layer composite ground.

关键词： analytical model     mechanical response     multi-layered ground     shallow tunneling     ground surface load     complex variable solution    

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Anisotropy of multi-layered structure with sliding and bonded interlayer conditions

Lingyun YOU, Kezhen YAN, Jianhong MAN, Nengyuan LIU

《结构与土木工程前沿（英文）》 2020年 第14卷 第3期   页码 632-645 doi: 10.1007/s11709-020-0617-4

摘要： A better understanding of the mechanical behavior of the multi-layered structure under external loading is the most important item for the structural design and the risk assessment. The objective of this study are to propose and develop an analytical solution for the mechanical behaviors of multi-layered structure generated by axisymmetric loading, and to investigate the impact of anisotropic layers and interlayer conditions on the multi-layered structure. To reach these objectives, first, according to the governing equations, the analytical solution for a single layer was formulated by adopting the spatial Hankel transform. Then the global matrix technique is applied to achieve the analytical solution of multi-layered structure in Hankel domain. The sliding and bonded interlayer conditions were considered in this process. Finally, the numerical inversion of integral transform was used to solve the components of displacement and stress in real domain. Gauss-Legendre quadrature is a key scheme in the numerical inversion process. Moreover, following by the verification of the proposed analytical solution, one typical three-layered flexible pavement was applied as the computing carrier of numerical analysis for the multi-layered structure. The results have shown that the anisotropic layers and the interlayer conditions significantly affect the mechanical behaviors of the proposed structure.

关键词： multi-layered structure     Hankel transformation     anisotropic     transversely isotropic     interlayer condition     Gauss-Legendre quadrature    

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Synergistic effect of V and Fe in Ni/Fe/V ternary layered double hydroxides for efficient and durable

《化学科学与工程前沿（英文）》 2023年 第17卷 第1期   页码 102-115 doi: 10.1007/s11705-022-2179-6

摘要： High-performance and stable electrocatalysts are vital for the oxygen evolution reaction (OER). Herein, via a one-pot hydrothermal method, Ni/Fe/V ternary layered double hydroxides (NiFeV-LDH) derived from Ni foam are fabricated to work as highly active and durable electrocatalysts for OER. By changing the feeding ratio of Fe and V salts, the prepared ternary hydroxides were optimized. At an Fe:V ratio of 0.5:0.5, NiFeV-LDH exhibits outstanding OER activity superior to that of the binary hydroxides, requiring overpotentials of 269 and 274 mV at 50 mA·cm–2 in the linear sweep voltammetry and sampled current voltammetry measurements, respectively. Importantly, NiFeV-LDH shows extraordinary long-term stability (≥ 75 h) at an extremely high current density of 200 mA·cm–2. In contrast, the binary hydroxides present quick decay at 200 mA·cm–2 or even reduced current densities (150 and 100 mA·cm–2). The outstanding OER performance of NiFeV-LDH benefits from the synergistic effect of V and Fe while doping the third metal into bimetallic hydroxide layers: (a) Fe plays a crucial role as the active site; (b) electron-withdrawing V stabilizes the high valence state of Fe, thus accelerating the OER process; (c) V further offers great stabilization for the formed intermediate of FeOOH, thus achieving superior durability.

关键词： oxygen evolution reaction     electrocatalysts     ternary layered double hydroxides     long-term stability    

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Layered alkali titanates (ATiO): possible uses for energy/environment issues

《能源前沿（英文）》 2021年 第15卷 第3期   页码 631-655 doi: 10.1007/s11708-021-0776-6

摘要： Uses of layered alkali titanates (A2TinO2n+1; Na2Ti3O7, K2Ti4O9, and Cs2Ti5O11) for energy and environmental issues are summarized. Layered alkali titanates of various structural types and compositions are regarded as a class of nanostructured materials based on titanium oxide frameworks. If compared with commonly known titanium dioxides (anatase and rutile), materials design based on layered alkali titanates is quite versatile due to the unique structure (nanosheet) and morphological characters (anisotropic particle shape). Recent development of various synthetic methods (solid-state reaction, flux method, and hydrothermal reaction) for controlling the particle shape and size of layered alkali titanates are discussed. The ion exchange ability of layered alkali titanate is used for the collection of metal ions from water as well as a way of their functionalization. These possible materials design made layered alkali titanates promising for energy (including catalysis, photocatalysts, and battery) and environmental (metal ion concentration from aqueous environments) applications.

关键词： layered alkali titanates     photocatalysis     hydrogen evdution     metal ions collection    

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标题 作者 时间 类型 操作

Synthesis, characterization and assessment thermal properties of clay based nanopigments

Mohammad Banimahd KIEVANI, Milad EDRAKI

期刊论文

Effect of the degree of template removal from mesoporous silicate materials on their adsorption of heavy

Farouq TWAIQ,M.S. NASSER,Sagheer A. ONAIZI

期刊论文

Capture of carbon dioxide over porous solid adsorbents lithium silicate, lithium aluminate and magnesium

P. V. Korake, A. G. Gaikwad

期刊论文

capture of carbon dioxide by transition metal aluminates, calcium aluminate, calcium zirconate, calcium silicate

Ganesh TILEKAR, Kiran SHINDE, Kishor KALE, Reshma RASKAR, Abaji GAIKWAD

期刊论文

Stability analysis of layered slopes in unsaturated soils

Guangyu DAI; Fei ZHANG; Yuke WANG

期刊论文

Quantification of seepage in a multi-layered disconnected river-aquifer system

Jiang LI, Haizhu HU, Xiaomin MAO, Yi LIU

期刊论文

Crack evolution of soft–hard composite layered rock-like specimens with two fissures under uniaxial compression

期刊论文

Hierarchically porous cellulose nanofibril aerogel decorated with polypyrrole and nickel-cobalt layered

期刊论文

Hydraulic fracturing pressure of concentric double-layered cylinder in cohesive soil

期刊论文

Size effects in two-dimensional layered materials modeled by couple stress elasticity

Wipavee WONGVIBOONSIN, Panos GOURGIOTIS, Chung Nguyen VAN, Suchart LIMKATANYU, Jaroon RUNGAMORNRAT

期刊论文

New pseudo-dynamic analysis of two-layered cohesive-friction soil slope and its numerical validation

Suman HAZARI, Sima GHOSH, Richi Prasad SHARMA

期刊论文

Mechanical responses of multi-layered ground due to shallow tunneling with arbitrary ground surface load

期刊论文

Anisotropy of multi-layered structure with sliding and bonded interlayer conditions

Lingyun YOU, Kezhen YAN, Jianhong MAN, Nengyuan LIU

期刊论文

Synergistic effect of V and Fe in Ni/Fe/V ternary layered double hydroxides for efficient and durable

期刊论文

Layered alkali titanates (ATiO): possible uses for energy/environment issues

期刊论文