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Mei Liang - One of the best experts on this subject based on the ideXlab platform.
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structure and properties of thermoplastic Saponite poly vinyl alcohol nanocomposites
Applied Clay Science, 2012Co-Authors: Weijun Zhen, Mei LiangAbstract:Abstract Thermoplastic Saponite/poly(vinyl alcohol) (PVA) nanocomposites were prepared by melting processing, in which water and formamide were used as plasticizer and Saponite as reinforcing filler. The microstructure of the Saponite/PVA nanocomposites was investigated by Fourier transform infrared spectra, Raman spectra, X-ray diffraction and transmission electron microscope. It was shown that formamide could form inter-molecular complexes with PVA through hydrogen bonds, which resulted in controlling the supermolecular structure of PVA, confining the crystallization of PVA and making PVA composites processable in melting state at relatively low temperature. Saponites influenced the molecular chain packing of PVA and confined its crystallization, which would be favorable for the melting processing of PVA. Saponite nanolayers were intercalated or partially exfoliated into PVA matrix and would enhance their dispersion as well as the interfacial adhesion with PVA matrix. Compared with PVA, Saponite/PVA nanocomposites exhibit remarkable improvement in mechanical properties, thermal stability, and water resistance.
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Structure and properties of thermoplastic Saponite/poly(vinyl alcohol) nanocomposites
Applied Clay Science, 2012Co-Authors: Weijun Zhen, Mei LiangAbstract:Abstract Thermoplastic Saponite/poly(vinyl alcohol) (PVA) nanocomposites were prepared by melting processing, in which water and formamide were used as plasticizer and Saponite as reinforcing filler. The microstructure of the Saponite/PVA nanocomposites was investigated by Fourier transform infrared spectra, Raman spectra, X-ray diffraction and transmission electron microscope. It was shown that formamide could form inter-molecular complexes with PVA through hydrogen bonds, which resulted in controlling the supermolecular structure of PVA, confining the crystallization of PVA and making PVA composites processable in melting state at relatively low temperature. Saponites influenced the molecular chain packing of PVA and confined its crystallization, which would be favorable for the melting processing of PVA. Saponite nanolayers were intercalated or partially exfoliated into PVA matrix and would enhance their dispersion as well as the interfacial adhesion with PVA matrix. Compared with PVA, Saponite/PVA nanocomposites exhibit remarkable improvement in mechanical properties, thermal stability, and water resistance.
Weijun Zhen - One of the best experts on this subject based on the ideXlab platform.
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Structure, properties and rheological behavior of thermoplastic poly(lactic acid)/quaternary fulvic acid-intercalated Saponite nanocomposites
Polymer Bulletin, 2015Co-Authors: Weijun Zhen, Wentao WangAbstract:Sodium humate was oxidized with nitric acid to obtain fulvic acid (FA), which was further quaternized to obtain quaternary fulvic acid (QFA). QFA-intercalated Saponite (QFA-Saponite) was prepared ultrasonically. Thermoplastic poly(lactic acid) (PLA)/quaternary fulvic acid-intercalated Saponite nanocomposites were prepared by melt intercalation technique. The morphology and dispersion of QFA-Saponite were investigated by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Mechanical properties, thermal stability and crystallization behavior of PLA/QFA-Saponite nanocomposites were also tested. Results showed a predominantly flocculated structure and partially intercalated morphology for QFA-Saponite. Mechanical testing and thermogravimetric analysis showed that the tensile strength, impact properties, and thermostability of PLA/QFA-Saponite nanocomposites improved significantly compared to pure PLA. Differential scanning calorimetry results showed that crystallinity of PLA increased from 22.5 to 68.3 % on addition of QFA-Saponite. Polarized optical microscopy showed QFA-Saponite as a nucleating agent for PLA that enhanced its crystallization rate. Rotational rheological behaviors of PLA/QFA-Saponite nanocomposites demonstrated that incorporation of QFA-Saponite increased rigidity of the network structure in PLA matrix.
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structure and properties of quaternary fulvic acid intercalated Saponite poly lactic acid nanocomposites
Applied Clay Science, 2015Co-Authors: Wentao Wang, Weijun Zhen, Shengzhen BianAbstract:Abstract Fulvic acid (FA) was prepared from humate sodium and nitric acid, and then quaternary fulvic acid (QFA) was synthesized from FA. QFA–intercalated Saponite (QFA–Saponite) was prepared using the ultrasonic radiation method. To improve the thermal and mechanical properties of poly(lactic acid) (PLA), QFA–Saponite/PLA nanocomposites were prepared from QFA–Saponite and PLA using the solution intercalation method. The microstructure of QFA–Saponite was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), indicating successful modification of QFA. The XRD analysis also showed that the QFA–Saponite/PLA nanocomposites consisted of intercalated and partially exfoliated structure. The thermal properties of the QFA–Saponite/PLA nanocomposites were investigated by thermal gravimetric analysis (TGA) and differential scanning calorimetric (DSC) analysis. Moreover, the antibacterial properties of the QFA–Saponite/PLA nanocomposites were studied. Because of the nanometer-sized dispersion of QFA–Saponite in the PLA matrix, the QFA–Saponite/PLA nanocomposites exhibited improved thermal and mechanical properties compared with pure PLA. When the content of QFA–Saponite was 1 wt.%, the QFA–Saponite/PLA nanocomposites exhibited optimum thermal and mechanical properties. The antibacterial properties of QFA–Saponite were endowed to the PLA-based nanocomposites.
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Structure and properties of quaternary fulvic acid–intercalated Saponite/poly(lactic acid) nanocomposites
Applied Clay Science, 2015Co-Authors: Wentao Wang, Weijun Zhen, Shengzhen BianAbstract:Abstract Fulvic acid (FA) was prepared from humate sodium and nitric acid, and then quaternary fulvic acid (QFA) was synthesized from FA. QFA–intercalated Saponite (QFA–Saponite) was prepared using the ultrasonic radiation method. To improve the thermal and mechanical properties of poly(lactic acid) (PLA), QFA–Saponite/PLA nanocomposites were prepared from QFA–Saponite and PLA using the solution intercalation method. The microstructure of QFA–Saponite was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), indicating successful modification of QFA. The XRD analysis also showed that the QFA–Saponite/PLA nanocomposites consisted of intercalated and partially exfoliated structure. The thermal properties of the QFA–Saponite/PLA nanocomposites were investigated by thermal gravimetric analysis (TGA) and differential scanning calorimetric (DSC) analysis. Moreover, the antibacterial properties of the QFA–Saponite/PLA nanocomposites were studied. Because of the nanometer-sized dispersion of QFA–Saponite in the PLA matrix, the QFA–Saponite/PLA nanocomposites exhibited improved thermal and mechanical properties compared with pure PLA. When the content of QFA–Saponite was 1 wt.%, the QFA–Saponite/PLA nanocomposites exhibited optimum thermal and mechanical properties. The antibacterial properties of QFA–Saponite were endowed to the PLA-based nanocomposites.
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In-situ Intercalative Polymerization of Poly( lactic acid)/HTCC-Saponite Nanocomposites and Their Properties Characterization
Chemical Journal of Chinese Universities-chinese, 2015Co-Authors: Weijun Zhen, Shenzhen BianAbstract:Water-soluble N-( 2-hydroxyl) propyl-3-trimethyl ammonium chitosan chloride( HTCC) was synthesized with 2,3-epoxypropyl trimethyl ammonium chloride( GTA) grafting to the amino groups of chitosan by two-step method. Then,chitosan quaternary ammonium intercalated Saponite( HTCC-Saponite) was synthesized with HTCC and Saponite under ultrasonication. Moreover,poly( lactic acid)( PLA) / HTCC-Saponite nanocomposites were prepared by means of in-situ intercalative polymerization with HTCC-Saponite and lactide. Orthogonal experiment showed the optimization polymerization parameters of PLA / HTCC-Saponite were as follows:the polymerization temperature was 150 ℃,the amount of stannous caprylate was 2%( mass fraction),the amount of HTCC Saponite was 1%( mass fraction) and the polymerization time was 16 h. The morphology analysis showed that the HTCC-Saponite appeared with intercalative or partially exfoliated structure. The microstructure,morphology and thermal properties of PLA / HTCC-Saponite nanocomposites were characterized by XRD,TEM,TG-DTG and DSC,respectively. The results showed that HTCC-Saponite obviously promoted the crystallinity and thermal stability of PLA. The antibacterial results showed that HTCC-Saponite had good antimicrobial properties,which was endowed in PLA / HTCC-Saponite nanocomposites.
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structure and properties of thermoplastic Saponite poly vinyl alcohol nanocomposites
Applied Clay Science, 2012Co-Authors: Weijun Zhen, Mei LiangAbstract:Abstract Thermoplastic Saponite/poly(vinyl alcohol) (PVA) nanocomposites were prepared by melting processing, in which water and formamide were used as plasticizer and Saponite as reinforcing filler. The microstructure of the Saponite/PVA nanocomposites was investigated by Fourier transform infrared spectra, Raman spectra, X-ray diffraction and transmission electron microscope. It was shown that formamide could form inter-molecular complexes with PVA through hydrogen bonds, which resulted in controlling the supermolecular structure of PVA, confining the crystallization of PVA and making PVA composites processable in melting state at relatively low temperature. Saponites influenced the molecular chain packing of PVA and confined its crystallization, which would be favorable for the melting processing of PVA. Saponite nanolayers were intercalated or partially exfoliated into PVA matrix and would enhance their dispersion as well as the interfacial adhesion with PVA matrix. Compared with PVA, Saponite/PVA nanocomposites exhibit remarkable improvement in mechanical properties, thermal stability, and water resistance.
Chiara Bisio - One of the best experts on this subject based on the ideXlab platform.
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synthetic Saponite clays as promising solids for lanthanide ion recovery
New Journal of Chemistry, 2020Co-Authors: Stefano Marchesi, Leonardo Marchese, Fabio Carniato, Matteo Guidotti, Mauro Botta, Chiara BisioAbstract:Extraction of lanthanide ions with different ionic radius (La3+, Gd3+ and Lu3+) from aqueous solutions was carried out by using two synthetic Saponite clays. The clays, prepared through a simple and low-cost hydrothermal approach, showed different particle size and cation-exchange capacity (CEC) and were characterized in order to evaluate the influence of their physico-chemical properties on the uptake process. Metal uptake tests, performed in pure water and simulated freshwater and seawater solutions, demonstrated that synthetic Saponites have a general good sorption capacity with high lanthanide capture after a few hours of contact. The solid samples showed a higher selectivity for Lu3+, due to its small ionic radius.
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An overview of the recent synthesis and functionalization methods of Saponite clay
New Journal of Chemistry, 2020Co-Authors: Fabio Carniato, Giorgio Gatti, Chiara BisioAbstract:The use of clay minerals has ancient origin and nowadays natural clays are extensively employed for a large number of applications, including in building, packaging, cosmetics, pharmaceutics and foundries. The major advantages of the use of natural clays are associated with their large availability and low price. However, when clays have a natural origin, extensive purification steps are required to remove inorganic and organic contaminants. In addition, depending on the genesis process and on the provenance site, the chemical composition of natural materials can be extremely variable. This variability represents a strong limitation for their application, especially when surface properties have to be strictly controlled. These reasons have stimulated scientists to develop synthetic materials whose structure and properties mimic those of natural layered materials. Synthetic Saponite clays have largely been investigated in this scenario and, through designed synthesis procedures, it was possible to obtain solids with controlled chemical compositions, tuneable layer dimensions and enhanced physico-chemical features. The purpose of this concise review is to give an overview of the physico-chemical properties of Saponite clays and of the strategies that in recent years have been adopted for their preparation and functionalization. In this respect, a number of papers are related to the modification of Saponites by substitution of cations in the interlayer space by organic surfactants, ions or hybrid compounds, thus extending their application. Moreover, a few examples concerning the insertion of specific ions (i.e. transition metal species) in the tetrahedral sheets of the clay through one-pot methods have also been reported recently. These materials, prepared through less time consuming methods, are characterized by the presence of well-defined metal sites that can be effectively exploited for several applications, such as heterogeneous catalysis. In this overview, after a summary on the most common intercalation compounds based on Saponite clays, attention was focused on the one-pot methods for the production of functional Saponite clays.
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size effect of synthetic Saponite clay in quasi solid electrolyte for dye sensititized solar cells
Solar Energy Materials and Solar Cells, 2013Co-Authors: Daniele Costenaro, Fabio Carniato, Chiara Bisio, Giorgio Gatti, Frederic Oswald, Toby B Meyer, Leonardo MarcheseAbstract:Abstract The use of a synthetic Saponite-clay with different morphological features is proposed in this work as additive for DSSC solar cells electrolyte. The dilution of the synthesis gel allowed to decrease the Saponite particle size from ca. 200 nm to ca. 50 nm and to obtain samples with different lamellae organization. The influence of these parameters on solar cell performances have been tested by dispersing 5 wt% of the clay in Z-946 liquid electrolyte and using the dispersion as non-liquid electrolyte. The stability of Saponite dispersions in methoxyproprionitrile solvent has been studied by Dynamic Light Scattering (DLS). The electrochemical characterization showed that the addition of the Saponite sample with the largest particles does not influence the solar cell efficiency, whereas the use of electrolyte having Saponite suspension with the smallest particle size led to an increase of solar cell efficiencies of 8% with respect to the reference cell. Finally, tests devoted to investigate the stability over the time of DSSC prepared by using quasi-solid Saponite-based electrolytes have been carried out.
Tsugio Sato - One of the best experts on this subject based on the ideXlab platform.
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solvothermal preparation of tio2 Saponite nanocomposites and photocatalytic activity
Applied Clay Science, 2009Co-Authors: Athanasia Nikolopoulou, Sridhar Komarneni, D. Papoulis, Dionisios Panagiotaras, George H. Kacandes, Peilin Zhang, Shu Yin, P Tsoliskatagas, Tsugio SatoAbstract:Abstract A Saponite-rich clay sample from western Macedonia, Greece was used for the preparation of TiO2–Saponite nanocomposites by solvothermal reaction of a mixture of water and ethanol as the solvent, hexamethylene tetramine as the precipitant and titanium trichloride as the TiO2 precursor. Phase composition was determined by X-ray diffraction (XRD) and particle morphology and elemental content was characterized by scanning electron microscopy and energy dispersive spectroscopy (SEM–EDS). These samples were also characterized by attenuated total reflection using Fourier transform infrared spectroscopy (ATR–FTIR). Particle-size analysis was carried out using dynamic light scattering method (DLS) and specific surface area and pore-size distribution analyses using BET N2 adsorption–desorption isotherms. The composite photocatalysts showed a mesoporous structure with the distribution of pore diameters centered at 3.8 and at 5.7–9.8 nm, with high specific surface areas. The photocatalytic activities of titania–Saponite nanocomposites in decomposing NOx gas were measured as a function of two different TiCl3–Saponite ratios. TiO2:Saponite with a mass ratio of 0.2:1 (Ti-Sap1) showed the highest photocatalytic activity because of its relatively large specific surface area and higher TiO2 content. Both the TiO2–Saponite nanocomposites showed higher photocatalytic activity than the standard titania (Degussa P25) based on TiO2 content because the titania was well dispersed on Saponite.
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Solvothermal preparation of TiO2/Saponite nanocomposites and photocatalytic activity
Applied Clay Science, 2009Co-Authors: Athanasia Nikolopoulou, Sridhar Komarneni, D. Papoulis, P. Tsolis-katagas, Dionisios Panagiotaras, George H. Kacandes, Peilin Zhang, Shu Yin, Tsugio SatoAbstract:Abstract A Saponite-rich clay sample from western Macedonia, Greece was used for the preparation of TiO2–Saponite nanocomposites by solvothermal reaction of a mixture of water and ethanol as the solvent, hexamethylene tetramine as the precipitant and titanium trichloride as the TiO2 precursor. Phase composition was determined by X-ray diffraction (XRD) and particle morphology and elemental content was characterized by scanning electron microscopy and energy dispersive spectroscopy (SEM–EDS). These samples were also characterized by attenuated total reflection using Fourier transform infrared spectroscopy (ATR–FTIR). Particle-size analysis was carried out using dynamic light scattering method (DLS) and specific surface area and pore-size distribution analyses using BET N2 adsorption–desorption isotherms. The composite photocatalysts showed a mesoporous structure with the distribution of pore diameters centered at 3.8 and at 5.7–9.8 nm, with high specific surface areas. The photocatalytic activities of titania–Saponite nanocomposites in decomposing NOx gas were measured as a function of two different TiCl3–Saponite ratios. TiO2:Saponite with a mass ratio of 0.2:1 (Ti-Sap1) showed the highest photocatalytic activity because of its relatively large specific surface area and higher TiO2 content. Both the TiO2–Saponite nanocomposites showed higher photocatalytic activity than the standard titania (Degussa P25) based on TiO2 content because the titania was well dispersed on Saponite.
Sridhar Komarneni - One of the best experts on this subject based on the ideXlab platform.
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Formation of Saponite by hydrothermal alteration of metal oxides: Implication for the rarity of hydrotalcite
American Mineralogist, 2019Co-Authors: Qi Tao, Manyou Chen, Qingjin Zeng, Sridhar KomarneniAbstract:AbstractConversion of hydrotalcite (Ht) to Saponite was observed by hydrothermal alkaline alteration of metal oxides. The conversion was through a pathway of hydration-dissolution-precipitation. It involved several critical steps, including the construction of Ht from metal oxides, dissolution of Al3+ from Ht, condensation of metasilicate anions with Ht, and finally crystallization of Saponite. The condensation was favored by relatively low Mg/Al ratios of Ht, along with high concentrations of Al3+ and silicate oligomers in the environment, resulting in highly crystalline Saponite. The latter conversion was greatly accelerated by the isomorphous substitution of Al3+ for Si4+ in silicate oligomers. The substitution generated the extra negative charge and led to the aforementioned condensation with Ht surface, thereby promoting the formation of Saponite TOT layers. During the process, CO2 is an indispensable component. Initially intercalated as CO32− to form Ht, CO2 was subsequently eliminated from the solid phase, and Saponite formed when the layer charge was reversed. Thus, this study presents a novel formation mechanism of Saponite from metal oxides via hydrotalcite and contributes to a better understanding of the crystallization, chemical stability, and transformation of Ht to Saponite. The results are also relevant to evaluating metal availability and carbon cycling on the surface of the Earth.
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hydrothermal transformation of mixed metal oxides and silicate anions to phyllosilicate under highly alkaline conditions
Applied Clay Science, 2018Co-Authors: Qi Tao, Manyou Chen, Sridhar KomarneniAbstract:Abstract Mixed metal oxides (MMO) were transformed to phyllosilicate in the presence of silicate anions under hydrothermal conditions. The product was shown to be Saponite with a trioctahedral layer structure by characterization with XRD, FTIR, 27 Al and 29 Si MAS NMR, HRTEM and TG-DTG. The formation of Saponite was through a rehydration-dissolution-precipitation pathway, involving the critical steps such as the reconstruction of MMO to hydrotalcite (Ht), exsolution of Al 3+ from Ht, condensation of metasilicate anions with Ht, and finally crystallization of Saponite. Isomorphous substitution of Al 3+ for Si 4+ in silicate oligomers is the key for the above conversion, which generated the negative charge necessary for the condensation between the silicate oligomers and Ht surface and the formation of 2:1 Saponite TOT layers. High pH value (over 14.0) favored the condensation of silicate oligomers and led to crystallization of Saponite. Thus, we report a novel method for the crystallization of Saponite.
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solvothermal preparation of tio2 Saponite nanocomposites and photocatalytic activity
Applied Clay Science, 2009Co-Authors: Athanasia Nikolopoulou, Sridhar Komarneni, D. Papoulis, Dionisios Panagiotaras, George H. Kacandes, Peilin Zhang, Shu Yin, P Tsoliskatagas, Tsugio SatoAbstract:Abstract A Saponite-rich clay sample from western Macedonia, Greece was used for the preparation of TiO2–Saponite nanocomposites by solvothermal reaction of a mixture of water and ethanol as the solvent, hexamethylene tetramine as the precipitant and titanium trichloride as the TiO2 precursor. Phase composition was determined by X-ray diffraction (XRD) and particle morphology and elemental content was characterized by scanning electron microscopy and energy dispersive spectroscopy (SEM–EDS). These samples were also characterized by attenuated total reflection using Fourier transform infrared spectroscopy (ATR–FTIR). Particle-size analysis was carried out using dynamic light scattering method (DLS) and specific surface area and pore-size distribution analyses using BET N2 adsorption–desorption isotherms. The composite photocatalysts showed a mesoporous structure with the distribution of pore diameters centered at 3.8 and at 5.7–9.8 nm, with high specific surface areas. The photocatalytic activities of titania–Saponite nanocomposites in decomposing NOx gas were measured as a function of two different TiCl3–Saponite ratios. TiO2:Saponite with a mass ratio of 0.2:1 (Ti-Sap1) showed the highest photocatalytic activity because of its relatively large specific surface area and higher TiO2 content. Both the TiO2–Saponite nanocomposites showed higher photocatalytic activity than the standard titania (Degussa P25) based on TiO2 content because the titania was well dispersed on Saponite.
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Solvothermal preparation of TiO2/Saponite nanocomposites and photocatalytic activity
Applied Clay Science, 2009Co-Authors: Athanasia Nikolopoulou, Sridhar Komarneni, D. Papoulis, P. Tsolis-katagas, Dionisios Panagiotaras, George H. Kacandes, Peilin Zhang, Shu Yin, Tsugio SatoAbstract:Abstract A Saponite-rich clay sample from western Macedonia, Greece was used for the preparation of TiO2–Saponite nanocomposites by solvothermal reaction of a mixture of water and ethanol as the solvent, hexamethylene tetramine as the precipitant and titanium trichloride as the TiO2 precursor. Phase composition was determined by X-ray diffraction (XRD) and particle morphology and elemental content was characterized by scanning electron microscopy and energy dispersive spectroscopy (SEM–EDS). These samples were also characterized by attenuated total reflection using Fourier transform infrared spectroscopy (ATR–FTIR). Particle-size analysis was carried out using dynamic light scattering method (DLS) and specific surface area and pore-size distribution analyses using BET N2 adsorption–desorption isotherms. The composite photocatalysts showed a mesoporous structure with the distribution of pore diameters centered at 3.8 and at 5.7–9.8 nm, with high specific surface areas. The photocatalytic activities of titania–Saponite nanocomposites in decomposing NOx gas were measured as a function of two different TiCl3–Saponite ratios. TiO2:Saponite with a mass ratio of 0.2:1 (Ti-Sap1) showed the highest photocatalytic activity because of its relatively large specific surface area and higher TiO2 content. Both the TiO2–Saponite nanocomposites showed higher photocatalytic activity than the standard titania (Degussa P25) based on TiO2 content because the titania was well dispersed on Saponite.
