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Guangren Qian - One of the best experts on this subject based on the ideXlab platform.
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an investigation into mechanism of Cation Adsorption by reconstruction of calcined layered double hydroxide
Microporous and Mesoporous Materials, 2017Co-Authors: Mengjie Wu, Jia Zhang, Yongqiang Peng, Jizhi Zhou, Xiuxiu Ruan, Yunfei Xi, Ray L Frost, Guangren QianAbstract:Abstract This work investigated the mechanism and limit of Cation Adsorption by reconstruction of calcined layered double hydroxide (CHT) for the first time. Mg x Al-CHT was used to adsorb Zn 2+ and Ni 2+ from aqueous solution. As a result, Adsorption amount of Cation was approximately equal to dissolved amount of Mg 2+ from CHT. In other words, the molar ratio was close to 1:1 between exchanged Cation (Zn 2+ or Ni 2+ ) and released Mg 2+ . Besides, Zn 2+ Adsorption and Mg 2+ dissolution took place synchronously until equilibrium. XRD and SEM indicated that CHT rebuilt layered double hydroxide (LDH) after adsorbing Zn 2+ and Ni 2+ . Furthermore, molar ratios of Mg 2+ /Zn 2+ and Mg 2+ /Ni 2+ were 1:1 in reconstructed CHT regardless of the original Mg 2+ /Al 3+ ratio. Based on these results, it was proposed that half of octahedral Al 3+ in LDH transformed into tetrahedral ones after calcination, resulting in half of Mg 2+ bond being distorted in CHT and ready for a potential exchange. When CHT was used to adsorb bivalent Cation (Me 2+ ), the maximum amount of Adsorption was the half amount of Mg 2+ , and MgMeAl-LDH was formed by dissociation-deposition.
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an investigation into mechanism of Cation Adsorption by reconstruction of calcined layered double hydroxide
Institute for Future Environments; Science & Engineering Faculty, 2017Co-Authors: Mengjie Wu, Jia Zhang, Yongqiang Peng, Jizhi Zhou, Xiuxiu Ruan, Yunfei Xi, Ray L Frost, Guangren QianAbstract:Highlights •Mechanism and limit of bivalent-Cation Adsorption by CHT were investigated. •Half of Mg 2 + in CHT was exchangeable independent of the initial Mg 2 +/Al 3 + ratio. •Mg 2 + linked to tetrahedral Al 3 + in CHT accounted for the exchangeable Cation. •Saturated Mg 2 +/Zn 2 + and Mg 2 +/Ni 2 + were close to 1:1 in the reconstructed LDH. •The conclusion was helpful in designing LDH-derived adsorbent and catalyst. Abstract This work investigated the mechanism and limit of Cation Adsorption by reconstruction of calcined layered double hydroxide (CHT) for the first time. MgxAl-CHT was used to adsorb Zn 2 + and Ni 2 + from aqueous solution. As a result, Adsorption amount of Cation was approximately equal to dissolved amount of Mg 2 + from CHT. In other words, the molar ratio was close to 1:1 between exchanged Cation (Zn 2 + or Ni 2 +) and released Mg 2 +. Besides, Zn 2 + Adsorption and Mg 2 + dissolution took place synchronously until equilibrium. XRD and SEM indicated that CHT rebuilt layered double hydroxide (LDH) after adsorbing Zn 2 + and Ni 2 +. Furthermore, molar ratios of Mg 2 +/Zn 2 + and Mg 2 +/Ni 2 + were 1:1 in reconstructed CHT regardless of the original Mg 2 +/Al 3 + ratio. Based on these results, it was proposed that half of octahedral Al 3 + in LDH transformed into tetrahedral ones after calcination, resulting in half of Mg 2 + bond being distorted in CHT and ready for a potential exchange. When CHT was used to adsorb bivalent Cation (Me 2 +), the maximum amount of Adsorption was the half amount of Mg 2 +, and MgMeAl-LDH was formed by dissociation-deposition.
Asao Oya - One of the best experts on this subject based on the ideXlab platform.
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Electric Double-Layer Capacitance of Meso/Macroporous Activated Carbon Fibers Prepared by the Blending Method
Journal of The Electrochemical Society, 2002Co-Authors: Soshi Shiraishi, Hideyuki Kurihara, Takuya Nakayama, Lan Shi, Asao OyaAbstract:Meso/macroporous activated carbon fibers (ACFs), containing mesopores and macropores in addition to micropores, were prepared from carbonization and steam-activation of the phenolic resin fibers blended with a small amount (0.1 wt %) of an organic nickel complex. Conventional (microporous) ACF as reference sample, mainly composed of micropores, was also prepared from pure phenolic resin fibers without any agent. The electric double-layer capacitance of these ACFs was measured in propylene carbonate containing 1.0 mol dm-3 LiClO4 (1.0 M LiClO4/PC). The correlation between the capacitance and the BET (Brunauer-Emmett-Teller) specific surface area of the microporous ACFs showed the nonlinearity due to strong ion-sieving of micropores. The double-layer capacitance of the meso/macroporous ACFs was higher than the microporous ACF, because the ion-sieving effect of micropores was relaxed by the presence of meso/macropores. The relaxation by the meso/macropores was enhanced for the Cation Adsorption or the high current density measurement. These results confirm that the presence of many meso/macropores promotes the formation of an effective double layer or fast transfer of ions in the microporous structure. © 2002 The Electrochemical Society. All rights reserved.
Claudio Airoldi - One of the best experts on this subject based on the ideXlab platform.
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RETRACTED: Performance of modified montmorillonite clay in mercury Adsorption process and thermodynamic studies
Inorganic Chemistry Communications, 2020Co-Authors: Denis L. Guerra, Claudio Airoldi, Rúbia R. VianaAbstract:The montmorillonite clay sample from amazon region, Para State, Brazil, was used for intercalation process with pyridine (P) and organofunctionalization with 3-aminopropyltriethoxysilane (APS). The montmorillonite-P/APS shows variation of d001 values, by changing d001 from 1.15 to 2.10 nm. The original and modified samples were used for mercury Cation Adsorption from aqueous solution at room temperature and pH 6.0. The energetic effect caused by mercury Cation Adsorption was determined though calorimetric titration at the solid–liquid interface and gave a net thermal effect that enabled the calculation of the exothermic values and the equilibrium constant. 2007 Elsevier B.V. All rights reserved.
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Adsorption of thorium Cation on modified clays mttz derivative
Journal of Hazardous Materials, 2009Co-Authors: Denis L. Guerra, Rúbia R. Viana, Claudio AiroldiAbstract:Abstract Diquite (D) and bentonite (B) mineral samples from the Amazon region, Brazil, were modified by MTTZ derivative (5-mercapto-1-methyltetrazole) using heterogeneous route. These materials were characterized by textural and elemental analysis, transmission electron microscopy (TEM), power X-ray diffraction and 13C NMR spectroscopy. The chemically modified clay (DMTTZ and BMTTZ) samples showed modifiCation of its physical–chemical properties including: specific area 41.4 (B) to 398.5 m2 g−1 (BMTTZ) and 25.0 (D) to 178.8 m2 g−1 (DMTTZ). The Adsorption experiments performed under batch process with Th(IV) concentration, pH and contact time as variables. The ability of these materials to remove thorium from aqueous solution was followed by a series of Adsorption isotherms adjusted to a Sips equation at room temperature and pH 2.0, with variable concentration of Th(IV). The maximum number of moles adsorbed was determined to be 10.45 × 10−2 and 12.76 × 10−2 mmol g−1 for DMTTZ and BMTTZ, respectively. The energetic effects (ΔintH°, ΔintG° and ΔintS°) caused by thorium Cation Adsorption were determined through calorimetric titrations.
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Adsorption of mercury Cation on chemically modified clay
Materials Research Bulletin, 2009Co-Authors: Denis L. Guerra, Rúbia R. Viana, Claudio AiroldiAbstract:Abstract A montmorillonite clay (M) sample from the Amazon region, Brazil, was intercalated with pyridine (Py), dimethyl sulfoxide (DS) and 3-aminopropyltriethoxysilane (APS). The chemically modified montmorillonite (M P/APS ) sample showed modifiCation of its physical–chemical properties including: specific area 41.39 m 2 g −1 (M) to 198.45 m 2 g −1 (M P/APS ). Solid-state 29 Si CPMAS/NMR of the silylated montmorillonite samples showed Q 2 and Q 3 signals as well as T 2 and T 3 signals. The appearance of T 2 and T 3 signals can be attributed to the grafting of APS to the interlayer surface silanol groups. The natural and modified clays were used for mercury Cation Adsorption from aqueous solutions at room temperature and pH 3.0. The energetic effects (Δ int H °, Δ int G ° and Δ int S °) caused by mercury Cation Adsorption were determined through calorimetric titrations.
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Hybrid aniline/silica xerogel Cation Adsorption and thermodynamics of interaction.
Journal of Colloid and Interface Science, 2004Co-Authors: Flávio A. Pavan, Ilauro S. Lima, Edilson Valmir Benvenutti, Yoshitaka Gushikem, Claudio AiroldiAbstract:Abstract Aniline groups chemically immobilized on silica through the sol–gel process were employed to extract divalent nickel and manganese from aqueous solutions at room temperature. The maximum Adsorption capacity of the xerogel was studied from Adsorption isotherms using a batch technique. The isotherms obtained were adjusted following the Langmuir equation. The xerogel adsorbent appears to have better affinity for nickel than manganese. From calorimetric titration, thermodynamic data on Cation/nitrogen basic atom interaction in the solid/liquid interface were determined. The enthalpic values, −0.46±0.02 and −0.29±0.02 kJ mol−1 for nickel and manganese, respectively, are in agreement with the low availability of the basic nitrogen atom on the aniline group and also the possible steric hindrance of the phenyl group bonded to nitrogen. However, thermodynamics indicated the existence of favorable conditions for such Cation–nitrogen interactions.
Catherine Louis - One of the best experts on this subject based on the ideXlab platform.
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Chemistry of Silica-Supported Cobalt Catalysts Prepared by Cation Adsorption. 2. Neoformation of Cobalt Phyllosilicate
Journal of Physical Chemistry C, 2008Co-Authors: Raquel Trujillano, Jean-françois Lambert, Catherine LouisAbstract:The goal of this study was to determine whether it was possible to avoid the formation of cobalt silicate during the preparation of silica-supported Co catalysts since this too-stable cobalt phase is detrimental to catalyst activity. The strategy was to use the strong chelating ligand ethanediamine (en) to complex Co Cations, then to adsorb them on silica, and to determine whether an optimal en:Co ratio could be found to avoid the formation of cobalt silicate. In a previous paper (Trujillano, R.; Villain, F.; Louis, C.; Lambert, J. F. J. Phys. Chem. C 2007, 111, 7152), which explored short contact times between Co complex solutions and silica (15 min and 2 h), it was found that cobalt ethanediamine adsorbed very quickly on silica. In the present paper, a longer contact time (7 days) was explored. XRD, UV−visible−near IR, and FT-IR characterization showed that after the fast phenomenon of Cation Adsorption, a second slow chemical phenomenon occurs, leading to the formation of cobalt phyllosilicate. The amo...
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mechanism of deposition of gold precursors onto tio2 during the preparation by Cation Adsorption and deposition precipitation with naoh and urea
Applied Catalysis A-general, 2005Co-Authors: Rodolfo Zanella, Laurent Delannoy, Catherine LouisAbstract:Gold on TiO2 prepared by Cation Adsorption (CA) and deposition–precipitation with urea (DP urea) and NaOH (DP NaOH) were characterized by various techniques during the preparation in order to determine the nature of the species deposited and the chemical phenomena occurring during these preparations. In the case of Cationic Adsorption of the [Au(en)2] 3+ complex, we showed that the preparation has to be performed at room temperature to avoid the decomposition of the complex and the reduction of gold. In such a way, small gold particles are obtained after calcination, but the gold loading is low. The methods of deposition–precipitation (DP NaOH and DP urea) involve both the deposition of a gold(III) species on the TiO2 surface, but the nature of these species is different. For the DP NaOH, we propose that [AuCl(OH)3] � , the main species present at the pH 8 of the preparation, reacts with hydroxyl groups of the TiO2 surface, and forms a grafted hydroxy-gold compound. This may explain the limited amount of gold deposited on TiO2 by this method. For the DP urea method, all the gold present in solution is deposited on the TiO2 surface as a gold(III) precipitate, which is not gold(III) hydroxide, but an amorphous compound containing nitrogen, oxygen and carbon. This compound arises from a reaction between the gold precursor and the products of decomposition of urea. The metallic gold particles obtained after calcination exhibit a decreasing size when the time of DP urea increases. We propose that the progressive increase of pH, due to urea decomposition at 80 8C, results in changes in the surface charge density of the gold precipitate particles, and leads to a fragmentation of the particles. # 2005 Elsevier B.V. All rights reserved.
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Mechanism of deposition of gold precursors onto TiO2 during the preparation by Cation Adsorption and deposition–precipitation with NaOH and urea
Applied Catalysis A-general, 2005Co-Authors: Rodolfo Zanella, Laurent Delannoy, Catherine LouisAbstract:Gold on TiO2 prepared by Cation Adsorption (CA) and deposition–precipitation with urea (DP urea) and NaOH (DP NaOH) were characterized by various techniques during the preparation in order to determine the nature of the species deposited and the chemical phenomena occurring during these preparations. In the case of Cationic Adsorption of the [Au(en)2] 3+ complex, we showed that the preparation has to be performed at room temperature to avoid the decomposition of the complex and the reduction of gold. In such a way, small gold particles are obtained after calcination, but the gold loading is low. The methods of deposition–precipitation (DP NaOH and DP urea) involve both the deposition of a gold(III) species on the TiO2 surface, but the nature of these species is different. For the DP NaOH, we propose that [AuCl(OH)3] � , the main species present at the pH 8 of the preparation, reacts with hydroxyl groups of the TiO2 surface, and forms a grafted hydroxy-gold compound. This may explain the limited amount of gold deposited on TiO2 by this method. For the DP urea method, all the gold present in solution is deposited on the TiO2 surface as a gold(III) precipitate, which is not gold(III) hydroxide, but an amorphous compound containing nitrogen, oxygen and carbon. This compound arises from a reaction between the gold precursor and the products of decomposition of urea. The metallic gold particles obtained after calcination exhibit a decreasing size when the time of DP urea increases. We propose that the progressive increase of pH, due to urea decomposition at 80 8C, results in changes in the surface charge density of the gold precipitate particles, and leads to a fragmentation of the particles. # 2005 Elsevier B.V. All rights reserved.
Mika Sillanpaa - One of the best experts on this subject based on the ideXlab platform.
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titanosilicates in Cation Adsorption and Cation exchange a review
Chemical Engineering Journal, 2017Co-Authors: Olga Oleksiienko, Christian Wolkersdorfer, Mika SillanpaaAbstract:Abstract The present work summarizes the relevant literature about Titanosilicates and appraises their current place among other inorganic sorption materials. A brief history of the sorbents of the TiSi family with their structural features is canvassed, typical synthesis approaches are addressed and TiSi Cation Adsorption and exchange appliCations are discussed. Suggestions for the directions and perspectives of further investigations are discussed in the reviews’ conclusions.
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Titanosilicates in Cation Adsorption and Cation exchange – A review
Chemical Engineering Journal, 2017Co-Authors: Olga Oleksiienko, Christian Wolkersdorfer, Mika SillanpaaAbstract:Abstract The present work summarizes the relevant literature about Titanosilicates and appraises their current place among other inorganic sorption materials. A brief history of the sorbents of the TiSi family with their structural features is canvassed, typical synthesis approaches are addressed and TiSi Cation Adsorption and exchange appliCations are discussed. Suggestions for the directions and perspectives of further investigations are discussed in the reviews’ conclusions.