Physicochemical Properties of Alkaline Aqueous Sodium Metaborate Solutions

2006 ◽  
Vol 4 (1) ◽  
pp. 88-98 ◽  
Author(s):  
Caroline R. Cloutier ◽  
Akram Alfantazi ◽  
Elod Gyenge
Keyword(s):  
Ionic Conductivity ◽  
Physicochemical Properties ◽  
Aqueous Solutions ◽  
Aqueous Media ◽  
Ion Concentration ◽  
X Ray Diffraction ◽  
Sodium Metaborate ◽  
Commercial Viability ◽  
The Impact ◽  
And Storage

Background: The transition to a hydrogen fuel economy is hindered by the lack of a practical storage method and concerns associated with its safe handling. Chemical hydrides have the potential to address these concerns. Sodium borohydride (sodium tetrahydroborate, NaBH4), is the most attractive chemical hydride for H2 generation and storage in automotive fuel cell applications, but recycling from sodium metaborate (NaBO2), is difficult and costly. An electrochemical regeneration process could represent an economically feasible and environmentally friendly solution. Method of Approach: We report a study of the properties of concentrated NaBO2 alkaline aqueous solutions that are necessary to the development of electrochemical recycling methods. The solubility, pH, density, conductivity, and viscosity of aqueous NaBO2 solutions containing varying weight percentages (1, 2, 3, 5, 7.5, and 10wt.%) of alkali hydroxides (NaOH, KOH, and LiOH) were evaluated at 25°C. The precipitates formed in supersaturated solutions were characterized by x-ray diffraction and scanning electron microscopy. Results: All NaBO2 physicochemical properties investigated, except solubility, increased with increased hydroxide ion concentration. The solubility of NaBO2 was enhanced by the addition of KOH to the saturated solution, but decreased when LiOH and NaOH were used. The highest ionic conductivity (198.27S∕m) was obtained from the filtrate of saturated aqueous solutions containing more than 30wt.%NaBO2 and 10wt.% NaOH prior to filtration. At 10wt.% hydroxide, the viscosity of the NaBO2 solution was the highest in the case of LiOH (11.38 cP) and lowest for those containing NaOH (6.37 cP). The precipitate was hydrated, NaBO2 for all hydroxides, but its hydration level was unclear. Conclusions: The use of KOH as the electrolyte was found to be more advantageous for the H2 storage and generation system based on NaBO2 solubility and solution half-life. However, the addition of NaOH led to the highest ionic conductivity, and its use seems more suitable for the electroreduction of NaBO2. Further investigations on the impact of KOH and NaOH on the electroreduction of NaBO2 in aqueous media have the potential to enhance the commercial viability of NaBH4.

Ionic conductivity in nanocrystalline Gd doped ceria

2008 ◽  
Vol 1122 ◽  
Author(s):  
Gianguido Baldinozzi ◽  
David Simeone ◽  
Dominique Gosset ◽  
Mickael Dollé ◽  
Georgette Petot-Ervas
Keyword(s):  
Grain Size ◽  
Ionic Conductivity ◽  
Sol Gel ◽  
Doped Ceria ◽  
Narrow Size Distribution ◽  
Conductivity Measurements ◽  
X Ray Diffraction ◽  
X Ray ◽  
Grain Sizes ◽  
The Impact

AbstractWe have synthesized Gd-doped ceria polycrystalline samples (5, 10, 15 %mol), having relative densities exceeding 95% and grain sizes between 30 and 160 nm after axial hot pressing (750 °C, 250 MPa). The samples were prepared by sintering nanopowders obtained by sol-gel chemistry methods having a very narrow size distribution centered at about 16 nm. SEM and X-ray diffraction were performed to characterize the sample microstructures and to assess their structures. We report ionic conductivity measurements using impedance spectroscopy. It is important to investigate the properties of these systems with sub-micrometric grains and as a function of their composition. Therefore, samples having micrometric and nanometric grain sizes (and different Gd content) were studied. Evidence of Gd segregation near the grain boundaries is given and the impact on the ionic conductivity, as a function of the grain size and Gd composition, is discussed and compared to microcrystalline samples.

scholarly journals Mechanism of magnesium transport in spinel chalcogenides

2021 ◽  
Author(s):  
Mohsen Sotoudeh ◽  
Manuel Dillenz ◽  
Axel Groß
Keyword(s):  
Ionic Conductivity ◽  
Ion Mobility ◽  
Density Functional ◽  
Electrode Materials ◽  
Critical Role ◽  
High Energy ◽  
Ion Concentration ◽  
Critical Parameters ◽  
Site Preference ◽  
The Impact

Abstract In the area of sustainable energy storage, batteries based on multivalent ions such as magnesium have been attracting considerable attention due to their potential for high energy densities. Furthermore, they are typically also more abundant than, e.g., lithium. However, as a challenge their low ion mobility in electrode materials remains. This study addresses the ionic conductivity of magnesium in spinel host materials based on periodic density functional theory calculations in order to identify the critical parameters which determine the mobility and insertion of ions. We will in particular highlight the critical role that trigonal distortions of the spinel structure play for the ion mobility. In detail, we will show that it is the competition between coordination and bond length that governs the Mg site preference in ternary spinel compounds upon trigonal distortions which can only be understood by also taking covalent interactions into account. Based on our theoretical study, we rationalize the impact of the metal distribution in the host material and the ion concentration on the diffusion process. Furthermore, cathode-related challenges for practical devices will be addressed. Our findings shed light on the fundamentional mechanisms underlying ionic conductivity in solid hosts and thus may contribute to improve ion transport in battery electrodes.

scholarly journals Mechanism of magnesium transport in spinel chalcogenides

2021 ◽  
Author(s):  
Mohsen Sotoudeh ◽  
Manuel Dillenz ◽  
Axel Groß
Keyword(s):  
Ionic Conductivity ◽  
Ion Mobility ◽  
Density Functional ◽  
Electrode Materials ◽  
Critical Role ◽  
High Energy ◽  
Ion Concentration ◽  
Critical Parameters ◽  
Site Preference ◽  
The Impact

Abstract In the area of sustainable energy storage, batteries based on multivalent ions such as magnesium have been attracting considerable attention due to their potential for high energy densities. Furthermore, they are typically also more abundant than, e.g., lithium. However, as a challenge their low ion mobility in electrode materials remains. This study addresses the ionic conductivity in spinel host materials which represent a promising class of cathode and solid-electrolyte materials in Mg-ion batteries. Based on periodic density functional theory calculations, we identify the critical parameters which determine the mobility and insertion of ions. We will in particular highlight the critical role that trigonal distortions of the spinel structure play for the ion mobility. In detail, we will show that it is the competition between coordination and bond length that governs the Mg site preference in ternary spinel compounds upon trigonal distortions. This can only be understood by also taking covalent interactions into account. Furthermore, our calculations suggest that anionic redox plays a much more important role in sulfide and selenide spinels than in oxide spinels. Based on our theoretical study, we rationalize the impact of the metal distribution in the host material and the ion concentration on the diffusion process. Furthermore, cathode-related challenges for practical devices will be addressed. Our findings shed light on the fundamentional mechanisms underlying ionic conductivity in solid hosts and thus may contribute to improve ion transport in battery electrodes.

scholarly journals Tetracycline Adsorption from Aqueous Media by Magnetically Separable Fe3O4@Methylcellulose/APTMS (Isotherm, Kinetic and Thermodynamic Studies)

2021 ◽  
Author(s):  
Sobhan Maleky ◽  
Ali Asadipour ◽  
Alireza Nasiri ◽  
Rafael Luque ◽  
Maryam Faraji
Keyword(s):  
Aqueous Solutions ◽  
Aqueous Media ◽  
Point Of Zero Charge ◽  
Gravimetric Analysis ◽  
Order Kinetic ◽  
X Ray Diffraction ◽  
Solution Ph ◽  
Enthalpy Changes ◽  
Isotherm Equations ◽  
Kinetic And Thermodynamic Studies

Abstract This study aimed to synthesize Fe3O4@Methylcellulose/3-Aminopropyltrimethoxysilane (Fe3O4@MC/APTMS) as a new magnetic nano-biocomposite by a facile, fast, and new microwave-assisted method and to be utilized as an adsorbent for tetracycline (TC) removal from aqueous solutions. Fe3O4@MC/APTMS was characterized by Fourier transform-infrared (FTIR), Field emission scanning electron microscopy (FESEM), Energy dispersive spectroscopy (EDS), Mapping, X-ray diffraction (XRD), Thermal gravimetric analysis (TGA), Brunauer–Emmett–Teller (BET) and vibrating sample magnetometer (VSM). The point of zero charge (pHzpc) value of the nano-biocomposite was estimated to be 6.8 by the solid addition method. Optimum conditions were obtained in TC concentration: 10 mg L−1, adsorbent dosage: 80 mg L−1, contact time: 90 min, and solution pH: 6 with the maximum TC removal of 90% and 65.41% in synthetic and actual samples, respectively. The kinetic and isotherm equations pointed to a pseudo-second order kinetic and Langmuir isotherm optimum fitting models. Based on the values of entropy changes (ΔS) (50.04 J/mol k), the enthalpy changes (ΔH) (9.26 kJ/mol), and the negative Gibbs free energy changes (ΔG), the adsorption process was endothermic, random, and spontaneous. The synthesized adsorbent exhibited outstanding properties, including proper removal efficiency of TC, excellent reusability, and simple separation from aqueous media by a magnet. Consequently, it is highly desirable that Fe3O4@MC/APTMS magnetic nano-biocomposite could be used as a promising adsorbent for TC adsorption from aqueous solutions.

scholarly journals Influence of Incorporation of Different dn-Electron Metal Cations into Biologically Active System on Its Biological and Physicochemical Properties

2021 ◽  
Vol 22 (23) ◽  
pp. 12909
Author(s):  
Bartłomiej Rogalewicz ◽  
Małgorzata Szczesio ◽  
Ewa Poleszak ◽  
Joanna Kowalczyk ◽  
Bernadeta Szewczyk ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Magnetic Measurements ◽  
Biological Properties ◽  
Biologically Active ◽  
X Ray Diffraction ◽  
Active System ◽  
X Ray ◽  
The Central Nervous System ◽  
New Compounds ◽  
The Impact

Three new compounds, namely [HL]2+[CuCl4]2−, [HL]2+[ZnCl4]2−, and [HL]2+[CdCl4]2− (where L: imipramine) were synthesized and their physicochemical and biological properties were thoroughly investigated. All three compounds form isostructural, crystalline systems, which havea been studied using Single-Crystal X-ray diffraction analysis (SC-XRD) and Fourier-transform infrared spectroscopy (FTIR). The thermal stability was investigated using thermogravimetric analysis (TGA) and melting points for all compounds have been determined. Magnetic measurements were performed in order to study the magnetic properties of the compounds. The above mentioned techniques allowed us to comprehensively examine the physicochemical properties of the newly obtained compounds. The biological activity was investigated using the number of Zebrafish tests, as it is one of the most common models for studying the impact of newly synthesized compounds on the central nervous system (CNS), since this model is very similar to the human CNS.

scholarly journals Arsenic(III) adsorption from aqueous solutions on novel carbon cryogel/ceria nanocomposite

2016 ◽  
Vol 10 (1) ◽  
pp. 17-23 ◽  
Author(s):  
Tamara Minovic-Arsic ◽  
Ana Kalijadis ◽  
Branko Matovic ◽  
Milovan Stoiljkovic ◽  
Jelena Pantic ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Adsorption Mechanism ◽  
Nitrogen Adsorption ◽  
Ion Concentration ◽  
X Ray Diffraction ◽  
Solution Ph ◽  
X Ray ◽  
Liquid Phase Adsorption ◽  
Bet Isotherm ◽  
Carbon Cryogel

Carbon cryogel/ceria composite, with 10 wt.% of ceria, was synthesized by mixing of ceria and carbon cryogel (CC). The sample was characterized by field emission scanning electron microscopy, nitrogen adsorption and X-ray diffraction. The adsorption of arsenic(III) ions from aqueous solutions on carbon cryogel/ceria nanocomposite was studied as a function of time, solution pH and As(III) ion concentration. The results are correlated with previous investigations of adsorption mechanism of arsenic(III) on carbon cryogel. Adsorption dose experiments showed that the mass of the adsorbent was reduced for 20 times, in comparison with pure CC, for the same amount of adsorbed arsenic(III) ions. BET isotherm was used to interpret the experimental data for modelling liquid phase adsorption.

scholarly journals Removal of Zinc Ions Using Hydroxyapatite and Study of Ultrasound Behavior of Aqueous Media

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1350 ◽  
Author(s):  
Simona Iconaru ◽  
Mikael Motelica-Heino ◽  
Régis Guegan ◽  
Mihai Predoi ◽  
Alina Prodan ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Aqueous Media ◽  
Zinc Ions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Wide Range ◽  
Ultrasonic Measurements ◽  
Ultrasonic Conditions ◽  
Langmuir And Freundlich Models

The present study demonstrates the effectiveness of hydroxyapatite nanopowders in the adsorption of zinc in aqueous solutions. The synthesized hydroxyapatites before (HAp) and after the adsorption of zinc (at a concentration of 50 mg/L) in solution (HApD) were characterized using X-ray diffraction (XRD), and scanning and transmission electron microscopy (SEM and TEM, respectively). The effectiveness of hydroxyapatite nanopowders in the adsorption of zinc in aqueous solutions was stressed out through ultrasonic measurements. Both Langmuir and Freundlich models properly fitted on a wide range of concentration the equilibrium adsorption isotherms, allowing us to precisely quantify the affinity of zinc to hydroxyapatite nanopowders and to probe the efficacy of hydroxyapatite in removal of zinc ions from aqueous solutions in ultrasonic conditions.

scholarly journals Impact of storage conditions and storage time on silver nanoparticles' physicochemical properties and implications for their biological effects

RSC Advances ◽  
2015 ◽  
Vol 5 (102) ◽  
pp. 84172-84185 ◽  
Author(s):  
E. Izak-Nau ◽  
A. Huk ◽  
B. Reidy ◽  
H. Uggerud ◽  
M. Vadset ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Physicochemical Properties ◽  
Storage Time ◽  
Biological Effects ◽  
Storage Conditions ◽  
Capping Agent ◽  
The Stability ◽  
The Impact ◽  
And Storage

A multi-parametric assessment of the impact of storage time/conditions and capping agent charge on the stability and toxicity of AgNPs showed agglomeration, dissolution, oxidation, capping agent degradation and attachment of Ag+ ions all play a role.

Di[(hydroxyalkyl)dimethylammonium] tris[benzene-1,2-diolato(2–)]silicates and their germanium analogs: syntheses, crystal structure analyses, and NMR studies

2000 ◽  
Vol 78 (11) ◽  
pp. 1380-1387
Author(s):  
Reinhold Tacke ◽  
Alistair Stewart ◽  
Joachim Becht ◽  
Christian Burschka ◽  
Ingo Richter
Keyword(s):  
Crystal Structure ◽  
Nmr Spectroscopy ◽  
Aqueous Solutions ◽  
Room Temperature ◽  
Model Systems ◽  
X Ray Diffraction ◽  
Nmr Studies ◽  
X Ray ◽  
Germanium Silicon ◽  
And Storage

Treatment of Si(OMe)4 with three molar equivalents of 1,2-C6H4(OH)2 (= 1,2-dihydroxybenzene) and two molar equivalents of HO(CH2)nNMe2 (n = 2, 3) in acetonitrile at room temperature yields the λ6Si-silicates (HO(CH2)nNMe2H)2(SiL3) (5: n = 2; 6: n = 3; L2– = 1,2-C6H4(O)22– (= benzene-1,2-diolato(2–))). The analogous λ6Ge-germanates (HO(CH2)nNMe2H)2(GeL3) (7: n = 2; 8: n = 3) were synthesized analogously starting from Ge(OMe)4. Compounds 5·2CH3CN and 6-8 were structurally characterized by single-crystal X-ray diffraction. In addition, aqueous solutions of the Si/Ge analogs 5/7 and 6/8 were studied by NMR spectroscopy. The title compounds may be regarded as model systems for the transport and storage of silicon in biological systems and as tools to investigate biosilification.Key words: hexacoordinate silicon, hexacoordinate germanium, silicon biochemistry

scholarly journals Preparation and physicochemical properties of the Fe, Mn-oxides catalyst

2021 ◽  
Vol 65 (1) ◽  
pp. 46-51
Author(s):  
A. I. Ivanets
Keyword(s):  
Physicochemical Properties ◽  
Oxide Catalyst ◽  
High Efficiency ◽  
Aqueous Media ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thermally Activated ◽  
Mn Oxide ◽  
Adsorption Desorption ◽  
Mn Oxides

A Fe, Mn-oxide catalyst was obtained by impregnation of thermally activated dolomite granules with aqueous solutions of Fe(III) and Mn(II) sulfates followed by heat treatment. Its physicochemical properties were studied using differential thermal analysis, X-ray diffraction, low-temperature adsorption-desorption of nitrogen, and scanning electron microscopy. The high efficiency of Fe(II) ion oxidation in aqueous media in a flow-type catalytic reactor was shown, which makes the obtained catalyst promising for the deironization of artesian waters.

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