Barium Hydroxide Octahydrate Research Articles

Experimental study on powdered expansion of barium hydroxide octahydrate crystal

Barium hydroxide octahydrate (BHO) will randomly pulverize and expand into a white powder during phase transformation, causing the container to deform or even rupture. This phenomenon seriously affects the practical application of BHO, but there is no research on the powdery expansion of BHO in the existing literature. In order to study the causes and influencing factors of the powdered expansion of BHO, the white powder, BHO and Barium carbonate (BC) were characterized by microscopic morphology and infrared spectrum, and the effect of additives on BHO crystallization was also investigated. The results show that the powdered expansion of BHO is its physical property, and no new substance will be produced during the expansion process, the expansion rate of BHO is 25%, as the cooling rate decreases, the probability of BHO powdered expansion increases; when the melting temperature of BHO reaches above 90 °C, the degree of undercooling will increase significantly, and the probability of powdered expansion increases. By adding hydroxyethyl cellulose, soluble starch and sodium dodecyl sulfonate, the radial expansion of BHO could be reduced to some extent, but it could not be prevented from happening.

Effect of Reagents on the Properties of Barium Titanate Synthesized in Subcritical Water

The structure and morphology of fine-crystalline barium titanate synthesized in a subcritical water fluid at 230°C and 2.9 MPa were studied. Barium oxide, barium hydroxide octahydrate (Ba(OH)2 · 8H2O), and two modifications of titanium oxide (rutile and anatase) were used as starting reactants. Relationships between the composition and properties of the reactants and the characteristics of the product (barium titanate) were revealed. They indicate that the product structure in the subcritical water is formed via a solidphase mechanism.

Experimental investigation of barium hydroxide octahydrate as latent heat storage materials

Phase change materials have a predominant role in heat storage technology. This paper focused on experimental study of barium hydroxide octahydrate (BHO-Ba(OH)2·8H2O), which is a low temperature phase change material with the melting point at 78 °C and a large latent heat with reported values in a range of 233 kJ/kg to 332 kJ/kg. Despite the great advantage of large heat capacity, it has significant supercooling and phase separation phenomena during the cooling process, which has limited its application. In this paper, five nucleating agents have been added to BHO to suppress the supercooling phenomena, including sodium borate, copper powder, calcium fluoride, calcium chloride and calgon. The experimental results indicated that the addition of 1% copper powder, 1% calcium fluoride, and 1% calgon by weight can reduce the supercooling degree to 2.7 °C, 1.8 °C and 2.3 °C respectively. In addition, gelatin has been used to suppress the phase separation phenomenon. The results indicate that the addition of 1% gelatin can hinder the phase separation by observing obvious less solid accumulations after 30 thermal cycles. Moreover, the thermal conductivity, specific heat capacity and corrosion characteristics were also measured in the experiments. The nucleating and gelling agents have successfully minimized the supercooling and phase separation issues of Ba(OH)2·8H2O, which is essential for its application as phase change material for thermal storage.

Following the Kinetics of Barium Titanate Nanocrystal Formation in Benzyl Alcohol Under Near-Ambient Conditions.

In complex chemical syntheses (e.g., coprecipitation reactions), nucleation, growth, and coarsening often occur concurrently, obscuring the individual processes. Improved knowledge of these processes will help to better understand and optimize the reaction protocol. Here, a form-free and model independent approach, based on a combination of time-resolved small/wide-angle X-ray scattering, is employed to elucidate the effect of reaction parameters (such as precursor concentration, reactant stoichiometry, and temperature) on the nucleation, crystallization, and growth phenomena during the formation of nanocrystalline barium titanate. The strength of this approach is that it relies solely on the total scattered intensity (i.e., scattering invariant) of the investigated system, and no prior knowledge is required. As such, it can be widely applied to other synthesis protocols and material's systems. Through the scattering invariant, it is found that the amorphous-to-crystalline transformation of barium titanate is predominantly determined by the total amount of water released from the gel-like barium hydroxide octahydrate precursor, and three rate-limiting regimes are established. As a result of this improved understanding of the effect of varying reaction conditions, elementary boundary conditions can be set up for a better control of the barium titanate nanocrystal synthesis.

Identification of best available thermal energy storage compounds for low-to-moderate temperature storage applications in buildings

Over the last 40 years different thermal energy storage materials have been investigated with the aim of enhancing energy efficiency in buildings, improving systems performance, and increasing the share of renewable energies. However, the main requirements for their efficient implementation are not fully met by most of them. This paper develops a comparative review of thermophysical properties of materials reported in the literature. The results show that the highest volumetric storage capacities for the best available sensible, latent and thermochemical storage materials are 250 MJ/m3, 514 MJ/m3 and 2000 MJ/m3, respectively, corresponding to water, barium hydroxide octahydrate, and magnesium chloride hexahydrate. A group of salt hydrates and inorganic eutectics have been identified as the most promising for the development of competitive thermal storage materials for cooling, heating and comfort applications in the short-term. In the long-term, thermochemical storage materials seem promising. However, additional research efforts are required.

Experimental Investigation of Improved Thermal Characteristics of Al2O3/Barium Hydroxide Octa Hydrate as Phase Change Materials (PCMs)

This paper presents an experimental investigation on phase change behavior of a newly prepared nanofluid as PCM containing barium hydroxide octa hydrate and Al2O3 nanoparticles (NPs). The nano-particles are dispersed into the base fluid in various mass fractions (0.5, 1.0, 1.5 and 2.0%) and their effects on the thermo-physical properties have been studied. Structural analysis has been carried out by using FESEM and crystallography was checked by XRD technique. Phase change temperatures and latent heats of composite PCMs were evaluated by differential scanning calorimetry (DSC) analyses.The test results clearly indicate that time required for phase change behavior of composite PCMs were less as compared to base PCM. Thus, the newly prepared PCM could be considered to be a potential candidate to produce the solar thermal energy storage materials.

Barium Hydroxide Octahydrate (Ba(OH)<sub>2</sub>·8H<sub>2</sub>O) as a Substitute Alternative for Barium Carbonate (BaCO<sub>3</sub>) in Synthesis Superconductor of Nd<sub>1</sub>Ba<sub>2</sub>Cu<sub>3</sub>O<sub>7-δ</sub> Phase

One of the basic ingredients in conventional preparation of cuprates-based superconducting materials such as the Nd-Ba-Cu-O superconducting system, especially the Nd1Ba2Cu3O7-δ phase is Barium Carbonate (BaCO3). It has the potential to produce the carbon dioxide (CO2) air pollutant. Therefore it is necessary to look for other materials as the source of Ba atom which does not produce CO2 gas. In this research has been successfully made the Nd1Ba2Cu3O7-δ phase with the Barium Hydroxide Octahydrate (Ba(OH)2·8H2O) as a source of Ba atom. The results of the characterization XRD has been shown the main peaks of the Nd1Ba2Cu3O7-δ phase. Refinement of the XRD data by using Rietica software, obtained the value of GofF (Goodness of Fit) = 1.7023 and lattice parameter a ≈ b < c/3 with a value of c/3 = 3.9275 A.

Study on improving the heat storage property of Ba(OH)2·8H2O with paraffin

Barium hydroxide octahydrate is the crystalline hydration salt with the highest latent heat density within the phase change temperature interval of 0–120 °C and it has a broad application prospect as a phase-change material (PCM). Firstly, red copper test tube was used for the melting—solidification heat cycle experiment in this paper, which was verified by the corrosion experiment of barium hydroxide solution. After the thermogravimetric analysis, it is found that paraffin can effectively reduce the evaporation escape of barium hydroxide octahydrate crystal water within 100 °C. Repeated heat cycle experiments indicated that the paraffin with larger coverage mass fraction can reduce the inhibiting effect of barium hydroxide octahydrate crystal water more obviously. X-ray diffraction analysis indicated that the phase composition of the barium hydroxide octahydrate sample covered with 50 wt% paraffin nearly had no change, while the sample not covered with paraffin has the weight loss ratio of 34.67% and reacted with CO2 in the air, generating BaCO3. In summary, paraffin can not only inhibit the evaporation of crystal water, but also effectively isolate the air to prevent barium hydroxide octahydrate from denaturation. This greatly improved the practicability of barium hydroxide octahydrate as a PCM, laying a good foundation for the further application of barium hydroxide octahydrate.

Synthesis and growth studies of barium titanates: 0−D and 1−D nanostructures using hydrogen titanate precursor

The present work demonstrates a simple and efficient route to synthesize a variety of barium titanate (BaTiO3) nanostructures including nanowires, nanoswords, nanostars, nanocubes, and nanoparticles by a facile hydrothermal approach. The experiments showed that different morphologies can easily be tuned by varying the concentration of precursors, i.e., hydrogen titanate (H2Ti3O7) and barium hydroxide octahydrate (Ba(OH)2.8H2O), while keeping the molar ratio, reaction temperature and time fixed. The structure and morphology of BaTiO3 were characterized by field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). The results indicate that BaTiO3 nanowires are in cubic phase with an average diameter of 80-100 nm. The shape of BaTiO3 changes from nanowires to nanoparticles with an increase in Ba(OH)2.8H2O concentration from 0.08 M to 0.51 M. Two possible mechanisms, in-situ topotactic transformation reaction and dissolution-deposition reaction have been suggested for different morphologies of BaTiO3. The synthesized 0-D and 1-D BaTiO3 nanostructures are promising materials for many applications because of their excellent dielectric, ferroelectric and piezoelectric properties. The present work will open a new route to single reaction parameter dependent synthesis of 0- and 1-D BaTiO3 nanostructures which can find a range of applications including electronics, catalysis, energy harvesting, etc.

Flux Growth of Highly Crystalline Photocatalytic BaTiO3 Particle Layers on Porous Titanium Sponge Substrate and Insights into the Formation Mechanism

A unique architecture of idiomorphic and highly crystalline BaTiO3 particle layers directly grown on a porous titanium sponge substrate was successfully achieved for the first time using a facile molten salt method at a relatively low temperature of 700 °C. Specifically, the low-melting KCl-NaCl eutectic salts and barium hydroxide octahydrate were employed as the reaction medium and barium source, respectively. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and UV-vis diffuse reflectance spectrophotometry were used to characterize the structure, morphology and optical property of the obtained samples. The results revealed that the flux-grown tetragonal BaTiO3 products had well-defined and uniform morphology with an average size of 300 nm and a band gap of ∼3.16 eV. Based on XRD, EDS, SEM, and TEM, the possible formation mechanism responsible for the well-developed architecture of BaTiO3 particle layers was proposed and discussed. Furthermore, the photocatalytic activity of the flux-grown BaTiO3 products for organic pollutant degradation under simulated sunlight irradiation was also investigated.

Energy and exergy analysis of a heat storage tank with a novel eutectic phase change material layer of a solar heater system

ABSTRACTSolar energy is one of the most important renewable energy sources, but it is not available every time and every season. Thus, storing of solar energy is important. One of the popular methods of heat storage is use of phase change materials (PCMs) which have large thermal energy storage capacity. In this study, the heat storage tank in a domestic solar water heating system was chosen as control volume. The experiments were performed in the province of Elazıg, Turkey, in November when solar radiation was weak due to cloudy sky. The heat storage tank of the system was modified to fill PCM between insulation and hot water part. A few PCMs which are Potassium Fluoride, Lithium Metaborate Dihydrate, Strontium Hydroxide Octahydrate, Barium Hydroxide Octahydrate, Aluminum Ammonium Sulfate, and Sodium Hydrogen Phosphate were analyzed to proper operating conditions using a Differential Scanning Calorimeter (DSC) and the best PCM was obtained with the Aluminum Ammonium Sulfate and Sodium Hydrogen Phosphate mixture. Thus, eutectic PCM was obtained and used in a heat storage tank of the solar water heating system. Energy and exergy analysis of heat storage tank was performed with and without the PCM. Energy and exergy analysis has shown that the heat storage tank with the PCM is more efficient than without the PCM and the maximum exergy efficiency was obtained as 22% with the heat storage tank with the PCM.

Two-step process for production of methyl ester from rubber seed oil using barium hydroxide octahydrate catalyst: Process optimization

Synthesis of rubber oil methyl ester (ROME) employing a two-step procedure, esterification using homogeneous catalyst followed by transesterification with heterogeneous catalyst was studied. The acid value of extracted RSO was reduced from 24 mg KOH/g to 2 mg KOH/g during esterification using 1.5 wt% catalyst loading (H2SO4) and 15:1 methanol to oil molar ratio for 2 h reaction time at 30 °C. Transesterification of esterified RSO with heterogeneous barium hydroxide octahydrate catalyst (Ba(OH)2·8H2O) was performed using conventional and ultrasonic techniques. Ultrasonic technique results in the increased yield of ROME compared to conventional process. The effect of catalyst Ba(OH)2·8H2O dehydration on the yield of ROME was also investigated in detail. The results showed that methyl ester conversion is not influenced by calcinations of catalyst. Highest transesterification yield was obtained with non-calcinated Ba(OH)2·8H2O compared to calcinated catalyst. But, within the studied calcinations temperature range, 400 °C showed significantly higher ROME conversion compared to 800 °C. BET analysis confirms lower surface area formation at 800 °C compared to other calcinated conditions. Central composite design (CCD) using response surface methodology (RSM) was adopted to design the experimental matrix and to optimize the combined effect of process parameters, reaction time (5–15min), catalyst loading (CL) (4–6wt%) and methanol to oil molar ratio (MR) (6:1–9:1) on ROME conversion. A second order model equation with p-value <0.05 was obtained to predict the conversion using the input parameters. Maximum conversion (∼97%) was achieved at CL of 5.38 wt% with MR of 8.09:1 in 13.20 min.

Low-temperature sintering behavior and properties of monoclinic-SrAl2Si2O8 ceramics prepared via an aqueous suspension milling process

In this work, by an aqueous suspension milling process, boric acid (H3BO3), calcium hydroxide [Ca(OH)2], strontium carbonate (SrCO3) and barium hydroxide octahydrate [Ba (OH)2·8H2O] are mixed with strontium carbonate (SrCO3) and kaolin (Al2O3·2SiO2·2H2O) to prepare SrAl2Si2O8 ceramics with a sintering temperature of 950 °C. According to chemical compositions of flux agents B2O3, CaO·2B2O3, SrO·2B2O3 and BaO·2B2O3, raw materials boric acid, calcium hydroxide, strontium carbonate and barium hydroxide octahydrate were introduced to the suspension slurries of strontium carbonate and kaolin to decrease the densification sintering temperature of SrAl2Si2O8 ceramics. In addition, the Sr element in SrAl2Si2O8 ceramics are partly substituted with Ba and Ca elements, respectively, to investigate the low-temperature sintering behavior of partly substituted SrAl2Si2O8 ceramics. The results indicated that the addition of flux agents to SrAl2Si2O8 ceramics can availably achieve the densification sintering of SrAl2Si2O8 ceramics at 950 °C, whereas the substitution of Sr with Ca or Ba have a great effect on sintering behaviors and dielectric properties of SrAl2Si2O8 ceramics. Additionally, main crystal phases of the SrAl2Si2O8 ceramics are monoclinic- SrAl2Si2O8 and small quartz, but the evolution of crystal phases also depend on flux agents.

The Effect of Nanometer Oxide Additive on the Heat-Conducting Property of Barium Hydroxide Octahydrate.

Nanometer silicon dioxide additive can improve the thermal performance of barium hydroxide octahydrate as the phase change thermal energy storage material. Through measuring the changes of phase change temperature, degree of supercooling, thermal conductivity, the different effects of nanometer silicon dioxide additives of different mass fraction on barium hydroxide octahydrate thermal performance are compared. It can be seen that the precipitation of barium hydroxide octahydrate with nanometer silicon dioxide additive of 0.5% mass fraction improves greatly. The thermal conductivity of barium hydroxide octahydrate with nanometer silicon dioxide additive of 0.5% mass fraction increases to a very slight degree.

Formation of nanocrystalline barium titanate in benzyl alcohol at room temperature.

Nanocrystalline barium titanate (8-10 nm crystallite size) was prepared at temperatures of 23-78 °C through reaction of a modified titanium alkoxide precursor in benzyl alcohol with barium hydroxide octahydrate. The room temperature formation of a perovskite phase from solution is associated with the use of benzyl alcohol as solvent medium. The formation mechanism was elucidated by studying the stability and interaction of each precursor with the solvent and with each other using various experimental characterization techniques. Density functional theory (DFT) computational models which agreed well with our experimental data could explain the formation of the solid phase. The stability of the Ti precursor was enhanced by steric hindrance exerted by phenylmethoxy ligands that originated from the benzyl alcohol solvent. Electron microscopy and X-ray diffraction indicated that the crystallite sizes were independent of the reaction temperature. Crystal growth was inhibited by the stabilizing phenylmethoxy groups present on the surface of the crystallites.

Experiment on thermal storage performance of barium hydroxide octahydrate phase change material

Experiment on thermal storage performance of barium hydroxide octahydrate phase change material

Electrophoretic deposition of BaTiO3 thin films from stable colloidal aqueous solutions

Polycrystalline BaTiO3 (BTO) thin films were electrodeposited on titanium foils from colloidal aqueous solutions of BTO nanoparticles which were synthesized by a hydrothermal process, under autogenous conditions. Two kinds of reactants have been studied: one involves an aqueous solution of titanium tetrachloride and barium hydroxide octahydrate without any added solvent, whereas the second was obtained by dispersing amorphous titanium oxide in different volumes of barium hydroxide aqueous solutions. The nanoparticles were characterized by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The particle size distribution (PSD) and the zeta potential measurements indicate that the colloids in the solution are polydisperse when using the first synthesis method, and they tend to be quasi monodisperse in the case of the second synthesis route. A porous microstructure of the electrodeposited films was detected by SEM. Finally, the dielectric properties of the BTO thin films were investigated.

Synthesis of Tetragonal BaTiO&lt;sub&gt;3&lt;/sub&gt; Powders via Alkoxide Method Assisted by Diethanolamine

The BaTiO3 precursor was prepared by alkoxide method, in which barium hydroxide octahydrate and butyl titanate were chosen as the Ba and Ti sources, and diethanolamine (DEA) as the polymerizing agent respectively. In order to determine the synthesis parameters of the target product, the phase transition process of the precursor with temperature increasing was investigated by TG-DTA. The effect of calcination temperature, the dosage of DEA and calcination time on the phase compositions and crystal structure of the synthesized samples were investigated by XRD. The results indicate that DEA can promote the formation of tetragonal BaTiO3 effectively, and the high-purity tetragonal BaTiO3 was obtained by heat treatment of the precursor at 1100°C for 3h with 1mL DEA dosage.

Crystal structure of 4,7-di-O-methyl 8,9-O-isopropylidine Neu5Ac methyl ester methyl ketoside, C18H31NO9

methyl ketoside (4.0 g) was treated with the barium oxide (5.84 g) and barium hydroxide octahydrate (0.69 g) in dr yd imethyl formamide (36 mL). After 10 min, methyl iodide (9.8 mL) was added, the reaction suspension was kept stirring for 45 hours at room temperature. The solids were filtered off and washed exhaustively with EtOAc. The filtrate was further extracted with EtOAc (60 mL) and 5%N aCl solution (30 mL )a nd evaporated under reduced pressure, giving the product in ay ield of 58. 4% . Colourless crystals were obtained by slow evaperation from the methanol solution containing the product.

Barium uranyl diphosphonates

Three Ba2+/UO22+ methylenediphosphonates have been prepared from mild hydrothermal treatment of uranium trioxide, methylendiphosphonic acid (C1P2) with barium hydroxide octahydrate, barium iodate monohydrate, and small aliquots of HF at 200°C. These compounds, Ba[UO2[CH2(PO3)2]·1.4H2O (Ba-1), Ba3[(UO2)4(CH2(PO3)2)2F6]·6H2O (Ba-2), and Ba2[(UO2)2(CH2(PO3)2)F4]·5.75H2O (Ba-3) all adopt layered structures based upon linear uranyl groups and disphosphonate molecules. Ba-2 and Ba-3 are similar in that they both have UO5F2 pentagonal bipyramids that are bridged and chelated by the diphosphonate moiety into a two-dimensional zigzag anionic sheet (Ba-2) and a one-dimensional ribbon anionic chain (Ba-3). Ba-1, has a single crystallographically unique uranium metal center where the C1P2 ligand solely bridges to form [UO2[CH2(PO3)2]2− sheets. The interlayer space of the structures is occupied by Ba2+, which, along with the fluoride ion, mediates the structure formed and maintains overall charge balance.