Concentrated Calcium Chloride Research Articles

Nano-carbon octadecahedron: in situ carbonization of DTAB of aggregates in concentrated calcium chloride solution

Morphologies play an important role in carbon nanomaterials. Carbon nanomaterials with different morphologies have different applications in different fields. However, carbon nano-polyhedra have been rarely reported in literatures. Nano-carbon octadecahedron were prepared by the interaction of DTAB of aggregates with a concentrated solution of calcium chloride at 600 °C and with a size of about 700 nm. A series of characterizations, such as SEM, FT-IR, XPS, XRD, Raman, etc., proved that it conforms to the basic characteristics of carbon nanomaterials and may be doped with Ca and carbon. Successful preparation of carbon octadecahedron suggests that the use of in situ carbonization in a concentrated salt system is a new and worthwhile approach to explore.

Effectiveness of thermal energy storage material and forced convection on the regeneration of liquid desiccant using hybrid solar still - An experimental study

Hybrid solar still has been investigated to desalinate the saline water and regenerate the weak liquid desiccant. An influence of thermal energy storage material (waste pieces of black granite) and forced convection (12 V direct current fan) was studied in terms of the water desorbed from the weak liquid desiccant and distilled water output from the saline water in two cases of the experiment. A 40% weight concentrated calcium chloride for Case-I and a 42% weight concentrated lithium chloride for Case-II as a weak liquid desiccant were used for the study and flown over the upper basin, whereas a saline water depth of 1 cm was maintained in the lower basin. The total daily desorbed water for Case-I was 761.33 ml/m2 and 796.00 ml/m2 for Case-II from the weak liquid desiccant. The total daily distillate output achieved for Case-I was 302.67 ml/m2 and 284.00 ml/m2 for Case-II. An increase in the concentration of liquid desiccant for Case-I was 2.42% and 1.37% for Case-II. When hybrid solar still will be used as a regenerator in the liquid desiccant-based solar cooling system, the regenerated liquid desiccant can able to adsorb the latent heat load of 0.1251 kW/d for Case-I and 0.1304 kW/d for Case-II from the humid air. For the bright sunshine hours, the daily average overall efficiency of 20.98% for Case-I and 27.76% for Case-II was obtained for the hybrid solar still.

Quantification of Calcium Oxychloride by Differential Scanning Calorimetry: Validation and Optimization of the Testing Procedure

Abstract The American Association of State Highway and Transportation Officials (AASHTO) T 365 standard, Standard Method of Test for Quantifying Calcium Oxychloride Formation Potential of Cementitious Pastes Exposed to Deicing Salts, describes a test methodology that uses low-temperature differential scanning calorimetry (LTDSC) to quantify the formation of calcium oxychloride in cementitious systems exposed to concentrated calcium chloride solutions. AASHTO T 365 is included in AASHTO PP 84, Standard Practice for Developing Performance Engineered Concrete Pavement Mixtures, as a performance indicator for mixtures at risk of calcium oxychloride formation. During the test, the sample temperature is first dropped to −90°C, looped through a brief thermal cycle, then slowly increased to a maximum of 50°C, at a constant heating rate of 0.25°C/minute (min), for a total testing time of approximately 11 hours. The objective of this work is to modify the test to reduce its duration to facilitate wide adoption among practitioners. It is found that by increasing the minimum conditioning temperature from −90°C to −5°C, as well as by increasing the heating rate from 0.25°C/min up to 1°C/min, the test duration can be reduced from approximately 10.7 hours to approximately 1.6 hours without any statistically significant difference in the numerical test results, although an offset of the melting peak and a change in its shape were observed. This change can provide valuable savings in terms of time and energy/gas consumption and make AASHTO T 365 more competitive with other available tests for the estimation of calcium oxychloride formation, such as thermogravimetric analysis (TGA). TGA and LTDSC are compared to each other in terms of mixture classification for susceptibility to calcium oxychloride formation. It is shown that the two tests show good agreement, with 85 % of cases (out of 30 tested) receiving the same classification.

Hybrid solar still as a co-generative system and desalination system - An experimental performance evaluation

An experimental evaluation of double basin hybrid solar still has been carried out as co-generative system and desalination system. The upper basin has dual-slope glass cover whereas lower basin has conventional single-slope glass cover. In the experiment of hybrid solar still as co-generative system, mixture of 33% concentrated magnesium chloride and 40% concentrated calcium chloride was flown through upper basin. Whereas in lower basin, the saline water depth of 0.01 ​m was retained with 0.10% w/w concentration of Zinc Oxide nanoparticles. In experiment of hybrid solar still as desalination system, saline water was flown through upper basin and the 0.01 ​m depth of saline water without nanoparticles was sustained in the lower basin. Desorbed water of 1.17 ​L/m2 from the upper basin and distillate of 0.28 ​L/m2 from the lower basin was obtained when hybrid solar still was examined as co-generative system. Whereas distillate yield of 0.63 ​L/m2 and 0.21 ​L/m2 was obtained from the upper and lower basin when hybrid solar still was utilized as desalination system. The experimental results revealed that maximum efficiency of 29.96% was achieved for hybrid solar still as co-generative system and 11.65% as desalination system. The outcome elucidate that an increment of 1.70% in concentration of mixture was achieved for hybrid solar still as co-generative system, which imparts 0.14 ​kW/m2 of latent cooling load.

Water Production from Air Using Multi-Shelves Solar Glass Pyramid System.(Dept.M)

The capability of the glass pyramid shape with multi-shelf solar system to extract water from humid air is explored. Two pyramids were used with different types of beds on the shelves. The beds are saturated with 30% concentrated Calcium Chloride solution. The pyramid sides were opened at night to allow the bed saturated with moist air and closed during the day to extract the moisture from the bed by solar radiation. The bed in the first pyramid was made of saw wood while it is made of only clothes in the second pyramid with the same dimensions. The system was experimentally investigated at different climatic conditions to study the effect of pyramid shape on the absorption and regeneration processes. Preliminary results have shown that the cloths bed absorbs more solution (9 kg) as compared to the saw wood bed (8 kg), Adopting this approach produce 2.8 Liter/day.m2. The use of the pyramid shape with four glass surfaces and multi-shelves enhances the produced water by about 90-95 % compared with solar desiccant/collector system with horizontal and corrugated beds. Results shows also that the clothes bed has higher productivity than that of saw wood bed by about 5% This is due mainly to the greater carrying solution at the onset of the experimental work. The obtained results may help in designing more efficient system.

Delicate Assembly of Ultrathin Hydroxyapatite Nanobelts with Nanoneedles Directed by Dissolved Cellulose.

Living organisms make use of a variety of inorganic and organic components to form biogenic minerals with hierarchical structures and fascinating properties, triggering the development of biomimetic mineralization. The introduction of organic additive is a versatile strategy, and a wide range of organics have already been adopted to mimic biosystems designing and synthesizing advanced functional minerals. Insoluble cellulose is the most abundant polysaccharide in nature, but the insolubility has limited its extensive applications. In this study, we first find that concentrated calcium chloride aqueous solution is an effective solvent for cellulose, and dissolved cellulose plays a pivotal role in directing the formation of ultrathin hydroxyapatite (HA) nanobelts of ca. 10 nm in thickness. To investigate the assembling process of the belt, samples collected at different reaction times were observed. The results indicate that nanoneedles form first, and then they assemble into the prototype of nanobelts by lateral/longitudinal aggregation and arrangement. Subsequently, the nanobelts gradually become dense, transparent, and smooth via crystallographic fusion of adjacent nanoneedles, indicating the highly elaborated evolution of morphology resulted from a time-dependent process. During the evolution of nanobelts, dissolved cellulose is supposed to participate in the mineralization of HA via the bonding of its hydrophilic groups with phosphate groups and calcium ions and the interaction of cellulose molecules with HA crystal planes. These findings provide unique insight into the application of dissolved cellulose in aqueous solution and an inspiration of a bottom-up strategy for designing delicate mineral assemblies directed by insoluble organics.

Calcite/aragonite-biocoated artificial coral reefs for marine parks

Natural formation of the coral reefs is complicated by slow biomediated precipitation of calcium carbonate from seawater. Therefore, manufactured artificial coral reefs can be used for the formation of “underwater gardens” in marine parks for the recreational fishing and diving that will protect natural coral reefs from negative anthropogenic effects. Additionally, the coating of the concrete, plastic or wooden surfaces of artificial coral reef with calcium carbonate layer could promote attachment and growth of coral larvae and photosynthetic epibiota on these surfaces. Three methods of biotechnological coating of the artificial coral reefs have been tested: (1) microbially induced calcium carbonate precipitation from concentrated calcium chloride solution using live bacterial culture of Bacillus sp. VS1 or dead but urease-active cells of Yaniella sp. VS8; (2) precipitation from calcium bicarbonate solution; (3) precipitation using aerobic oxidation of calcium acetate by bacteria Bacillus ginsengi strain VSA1. The thickness of biotechnologically produced calcium carbonate coating layer was from 0.3 to 3 mm. Biocoating using calcium salt and urea produced calcite in fresh water and aragonite in seawater. The calcium carbonate-coated surfaces were colonized in aquarium with seawater and hard corals as inoculum or in aquarium with fresh water using cyanobacteria Chlorella sorokiana as inoculum. The biofilm on the light-exposed side of calcium carbonate-coated surfaces was formed after six weeks of incubation and developed up to the average thickness of 250 µm in seawater and about 150 µm in fresh water after six weeks of incubation. The biotechnological manufacturing of calcium carbonate-coated concrete, plastic, or wooden surfaces of the structures imitating natural coral reef is technologically feasible. It could be commercially attractive solution for the introduction of aesthetically pleasant artificial coral reefs in marine parks and resorts.

Raman spectroscopic study on NpO2 +–Ca2+ interaction in highly concentrated calcium chloride

Coordination circumstance of neptunyl ion in concentrated CaCl2 solutions was analyzed by Raman spectrometry. Besides the symmetric stretch (ν1) mode of NpO2 + and NpO2 2+, the asymmetric stretch (ν3) mode of NpO2 + was found. The Raman intensity of the ν3 mode increased with the concentration of CaCl2 in the system. This would be attributable to the cation–cation interaction between Np(V) and Ca(II).

Buoyancy Driven Mass Transfer in a Liquid Desiccant Storage Tank

A new concept for long-term solar thermal storage is based on the absorption properties of aqueous calcium chloride. Water, diluted and concentrated calcium chloride solutions are stored in a single tank. An immersed heat exchanger and stratification manifold are used to preserve long-term sorption storage, and to achieve thermal stratification. The feasibility of sensible heating the tank via large-scale natural convection without mixing salt solutions is demonstrated via measurements of velocity, CaCl2 mass fraction, and temperature in a 1500 l prototype tank. Experiments are conducted over a practical range of the relevant dimensionless parameters. For Rayleigh numbers from 3.4 × 108 to 5.6 × 1010 and buoyancy ratios from 0.8 to 46.2, measured Sherwood numbers are 11 ± 2 to 62 ± 9, and the tank is thermally stratified. Convective mixing between salt layers is inhibited by the presence of a steep density gradient at the interface between regions of differing mass fraction. The predicted storage time scales based on mixing via natural convection for the reported Sherwood numbers are 160–902 days.

Application of osmotic membrane distillation process in red grape juice concentration

The osmotic membrane distillation process was applied in dehydration of red grape juice (Most de Raïm Concentrat Negre) of different concentrations (5–20°Brix). Experiments were performed using polytetrafluoroethylene (PTFE) hydrophobic membranes of different nominal pore diameter. Red grape juice solution and concentrated calcium chloride solution (50wt.%) were used as feed and stripping solutions, respectively. The permeate flux, the initial and the final juice concentration, the total phenolic content (TPC) and the antioxidant activity (TEAC) were measured for each single experiment.It was found that the final juice concentration was proportional to the time of the OMD dehydration process and the initial juice concentration. Results showed that during the concentration of juices by the OMD dehydration process the physicochemical properties like the total phenolic index and the antioxidant activity are well preserved.

Electrochemical deposition of uranium oxide in highly concentrated calcium chloride

The coordination circumstances and redox reactions of UO2 2+ in the aqueous solution concentrated by calcium chloride, such as CaCl2·6H2O (6.9 M CaCl2), were studied by Raman spectroscopy and electrochemical methods. The frequency of the O=U=O symmetrical stretching vibration suggested that the complex formation of UO2 2+ with Cl− leads to the weakening of U=O bond. In the electrochemical measurements, two-step cathodic currents were observed at −0.090 and −0.4 V (vs. Ag|AgCl) corresponding to the reduction of UO2 2+ to UO2 + and that of UO2 + to UO2, respectively. It was found that UO2 + formed at first cathodic current was disproportionated to form UO2 2+ and UO2. The UO2 was identified by X-ray diffraction analysis. Electrolytic deposition of UO2 was observed in 6.9–4.7 M CaCl2 and in 14 M LiCl. When small amount of proton, i.e., 0.005 M was coexisted in 6.9 M CaCl2, UO2 2+ was reduced to form U4+ instead of UO2.

Preparation of thorium concentrate from concentrated calcium chloride solutions

Extraction, washing, back extraction, and precipitation of Th(IV) from the backwash in the hydrochloric acid processing of perovskite are studied. Process conditions are optimized to obtain a concentrate with a ThO2 content of about 85 wt %.

Calcite Mesocrystals: “Morphing” Crystals by a Polyelectrolyte

Crystallization of calcite from different concentrated calcium chloride solutions by the CO(2) vapor diffusion technique in the presence of polystyrenesulfonate (PSS) yields defined assemblies of nanoparticles with unusual morphology. From the typical calcite rhombohedra, the morphology can be systematically varied via rounded edges and truncated triangles to concavely bent lens-like shapes. Although these "crystals" are apparently well facetted as observed in light microscopy, electron microscopy analysis and BET isotherms reveal that the structures are highly porous and are composed of almost perfectly three-dimensionally aligned calcite nanocrystals, scaffolded to the final, partly curved structures. The formation of all mesostructures is discussed within the framework of a polymer-mediated structure-formation process, in which the polymer is acting in four different ways. The present model case also provides evidence for the importance of nonclassical mesoscopic processes in polymer-controlled crystallization in general.

Water production from air using multi-shelves solar glass pyramid system

The capability of the glass pyramid shape with a multi-shelf solar system to extract water from humid air is explored. Two pyramids were used with different types of beds on the shelves. The beds are saturated with 30% concentrated Calcium Chloride solution. The pyramid sides were opened at night to allow the bed saturated with moist air and closed during the day to extract the moisture from the bed by solar radiation. The bed in the first pyramid was made of saw wood while it is made of only cloth in the second pyramid with the same dimensions. The system was experimentally investigated at different climatic conditions to study the effect of pyramid shape on the absorption and regeneration processes. Preliminary results have shown that the cloths bed absorbs more solution (9 kg) as compared to the saw wood bed (8 kg). Adopting this approach produces 2.5 L/day m 2. The use of the pyramid shape with four glass surfaces and multi-shelves enhances the produced water by 90–95% compared with solar desiccant/collector system with horizontal and corrugated beds. Results also show that the clothes bed has higher productivity than that of saw wood bed by about 5%. This is due mainly to the greater carrying solution at the onset of the experimental work. The obtained results may help in designing more efficient system.

Evolution of Chemistry and Its Effects on the Corrosion of Engineered Barrier Materials

ABSTRACTThe evolution of environmental conditions within the emplacement drifts of a potential high-level waste repository at Yucca Mountain, Nevada, may be influenced by several factors, including the temperature and relative humidity within the emplacement drifts and the composition of seepage water. The performance of the waste package and the drip shield may be affected by the evolution of the environmental conditions within the emplacement drifts. In this study, tests evaluated the evolution of environmental conditions on the waste package surfaces and in the surrounding host rock. The tests were designed to (i) simulate the conditions expected within the emplacement drifts; (ii) measure the changes in near-field chemistry; and (iii) determine environmental influence on the performance of the engineered barrier materials. Results of tests conducted in this study indicate the composition of salt deposits was consistent with the initial dilute water chemistry. Salts and possibly concentrated calcium chloride brines may be more aggressive than either neutral or alkaline brines.

Nonclassical Crystallization: Mesocrystals and Morphology Change of CaCO3 Crystals in the Presence of a Polyelectrolyte Additive

Crystallization of calcite from differently concentrated calcium chloride solutions by the CO2 gas diffusion technique in the presence of polystyrene sulfonate yields crystal superstructures with unusual morphology. From the typical calcite rhombohedra as a starting situation, the morphology can be systematically varied via rounded edges and truncated triangles to finally concavely bended lens-like superstructures. Although these "crystals" are apparently well-faceted in light microscopy, electron microscopy analysis and BET reveal that the structures are highly porous and are composed of almost perfectly 3D-aligned calcite nanocrystals scaffolded to the final, partly nicely curved superstructures. At high supersaturations, superstructures with changed symmetry indicative of dipolar interaction potentials between the building blocks are found. The present model case also gives evidence for the importance of nonclassical, mesoscopic processes in crystallization in general.

Experimental investigation of the stratified flow in the horizontal pipework of nuclear reactors

Abstract Laboratory tests have been performed to study the behaviour of a stratified fluid flow in horizontal piping. Concentrated calcium chloride brine and fresh water at room temperature were used to model the density difference due to thermal effects in nuclear reactors. Flow phenomena relating to the interface and mixing of the two layers were observed through the plexiglass piping by means of a flow visualization technique involving a longitudinal laser beam section through the flow. The measurements have established that, at the representative flow conditions modelled by the experiments, despite the presence of strong surface waves on the interface, little mixing occurs between the two layers. Quantitative correlations for the depth of the interface between the two layers, its surface slope and the height of surface waves have been established by the definition and use of two dimensionless Froude numbers.

Structural changes and dyeability of silk fibroin fiber following shrinkage in neutral salt solution

AbstractThe fine structural changes of Bombyx mori silk fibroin fibers, induced by shrinking with concentrated calcium chloride aqueous solution at elevated temperature were investigated as a function of shrinking rate. Tensile strength decreased and elongation at break increased in the shrinkage range 13–67%, the shape of the stress–strain curve changing from rubberlike to brittle at high shrinkage values (70–90%). The birefringence gradually decreased over the entire shrinking range examined, the curve becoming steep as the shrinkage exceeded about 67%. The behavior of isotropic refractive index (niso) closely resembled that of birefringence (Δn) in the shrinking range 13–67%. Beyond shrinkage of 67%, the niso showed a tendency to increase, especially for the sample with 80% shrinkage. Dichroism measurements showed that the molecular orientation within the amorphous regions decreased sharply at the beginning of the shrinking treatment, within the range 0–13%, then attained a saturation at about 55%. The position and intensity of the major X‐ray diffraction peak at 20.5° remained essentially unchanged regardless of the shrinking treatment. The results of dyeing behavior showed that the saturation value attained by shrunk silk fibers was significantly larger than that of the untreated control sample. Both standard affinity and the heat of dyeing increased slightly for the shrunk silk fibroin fiber, suggesting that a larger number of reactive sites became available for the interaction between dye molecules and fibroin chains. A schematic model is proposed for explaining the relation between structural changes and enhanced dyeability of the silk fibers following shrinkage in neutral salt solution. © 1994 John Wiley & Sons, Inc.

アルジネート印象に注入した超硬せっこう模型面の硬化状態の改善法 塩化カルシウム濃厚溶液による印象材表面処理の効果

To improve the surface quality and roughness of die stone poured into the alginate hydrocolloid impression, the surface of impression was pretreated with the concentrated calcium chloride solution, ranging from 5 to 40% by weight, for 30 seconds.The SEM observation and the surface roughness measurement for the stone surfaces which was set on the modified impressions revealed that the dihydrate crystals grew more densely at the surface than that for the stone surfaces which were produced from the impressions not pretreated or pretreated with the conventional fixing solutions, 2% potassium sulfate solution or 2% zinc sulfate solution, and that the excellent smooth surface comparable to the stone surface from addition silicone impressions was obtained by the pretreatment with 10-20% calcium chloride solution.It was suggested that the die stone poured into the alginate hydrocolloid impressions pretreated with the new fixing solution was availabe as a working model in dental pracitice.

The Fixing Effect of Concentrated Calcium Chloride Solutions to the Surface of Alginate Hydrocolloid Impressions : Setting Reaction of the Stone Surface on the Impressions

The Fixing Effect of Concentrated Calcium Chloride Solutions to the Surface of Alginate Hydrocolloid Impressions : Setting Reaction of the Stone Surface on the Impressions