Concentrated Calcium Chloride Solution 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.

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.

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.

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.

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.

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.

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.

A Method for the Aqueous Deacidification of Oxidized Paper

Concentrated aqueous solutions of pH-neutral salts were evaluated for their effectiveness at deacidifying photo-oxidized filter paper. Short immersions in these solutions successfully neutralized acidic paper sheets. However, subsequent rinses to remove excess salt were necessary to prevent yellowing upon thermal aging. Sheets treated with concentrated solutions of calcium chloride showed no significant chemical damage from the treatment and deteriorated more slowly during thermal aging compared with untreated sheets. Sample papers that were given a dilute alkaline rinse after the concentrated salt treatment degraded less upon thermal aging than papers treated with either solution alone. This method of neutral deacidification was also evaluated for use prior to chemical reduction of oxidized paper with sodium borohydride. A treatment procedure involving steps of deacidification, chemical reduction, and alkalization was found to greatly stabilize photo-oxidized papers against thermal aging, as well as to produce a bleaching effect.

Determination of Cadmium, Cobalt, Manganese, Copper, Nickel, and Chromium in Concentrated Solutions of Calcium Chloride by Electrothermal Atomic Absorption Spectrometry

A procedure is developed for the direct determination of Cd, Co, Cr, Cu, Mn, and Ni in concentrated solutions of calcium chloride by electrothermal atomic absorption spectrometry. Ascorbic and oxalic acids and magnesium nitrate were examined as chemical modifiers. Oxalic acid was found to be the best modifier. Although an atomic absorption spectrometer with a background correction system of relatively low efficiency (deuterium lamp) was used, the elements under study can be reliably determined in the presence of oxalic acid at concentrations of calcium chloride in the solution up to 6%. Because cadmium is evaporated before the major part of the given matrix, it can be determined without a modifier.

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

Modifications in crystal size distribution as a measure of impurity effect on crystallization

Calcium oxalate was precipitated by simultaneous mixing of concentrated solutions of calcium chloride and sodium oxalate which generated a supersaturation of about 10 4. The precipitate was viewed in the flow cell of a Computerized Inspection System (CIS-1) and detailed crystal size distribution (CSD) analysis was performed. It seems that the combined nucleation-growth-aggregation process is largely stochastic, giving CSD results of non-Gaussian character and unsatisfactory reproducibility. Addition of traces of phosphonic acids shifts the CSD to smaller sizes, but does not allow quantitative evaluation because of poor reproducibility. Dispersing agents improve slightly the possibility of correct estimation of the effect of additives on the formation of calcium oxalate by the extent of its CSD modification. However, only the combined effect of molecules, one of which may act as a nucleating agent and another which has a pronounced inhibitory/antiaggregating effect, achieves reproducibility in the CSD shifts.

Densities and apparent molal volumes of aqueous concentrated calcium chloride solutions from 50 to 200�C at 20.27 bar

Densities of aqueous calcium chloride solutions are reported for molalities up to 6.4 mol-kg−1 at temperatures from 50 to 200°C and at 20.27 bar. Apparent molar volumes calculated from experimental densities were fitted to the equations of Rogers and Pitzer, and the temperature dependence of the Pitzer parameters were obtained. The standard deviation of fit for the apparent molar volumes is 0.21 cm3-mol−1 from 50 to 200°C at 20.27 bar.

Selective absorption of hydrogen chloride from flue gases in the presence of sulfur dioxide

AbstractDetailed results of static and dynamic experiments to determine the vapor‐liquid equilibrium for HCl and the co‐absorption of hydrogen chloride and sulfur dioxide in concentrated solutions of calcium chloride.

Studies of porous polymer gels. I. One-step suspension technique for preparation of moderately crosslinked methacrylic acid gels

A new method of preparation of carboxyl cation exchangers directly from methacrylic acid and divinylbenzene is described. A suspension technique with a concentrated aqueous calcium chloride solution as the water phase was used. n-Octane and toluene were inert diluents of the monomers. The copolymers obtained have high ion-exchange capacity (9.6–10.6 mequ./g) and porous structure.

Biogeochemistry of organic matter—I: Polypeptides and amino acids in fossils and sediments in relation to geothermometry

Quantitative data are presented on ninhydrin-reacting substances in hydrolysates and extracts of Recent sediments, sedimentary rocks, and fossils, as determined by column chromatography. The recovery of amino acids added in small amounts to a concentrated calcium chloride solution was found to be 94-96 per cent, after precipitation of the calcium as calcium sulphate and removal of the HCl by vacuum distillation. Seventeen amino acids and three unknowns were detected in hydrolysates of surface and subsurface sediment samples, from Lake Opinicon, Ontario, with amino acids and other ninhydrin-reacting organic compounds accounting for nearly two-thirds of the soluble-N in the hydrolysate, and ammonia for most of the remaining third. Only five amino acids, (aspartic acid, glutamic acid alanine, leucine(s) and γ-aminobutyric acid) and one unidentified ninhydrin-reacting organic compound were present in a hydrolysate of shale from the Green River formation, (Eocene). Amino acids accounted for only 0.014 per cent of the total-N in the shale. It was calculated from the alanine content that the maximum temperature that the Green River shale could have been continuously subjected to during its history was 74°C. Amino acids were not detected in hydrolysates of two pre-Cambrian sedimentary rocks, nor in it hydrolysate of a Miocene lignite. An acid extract of carnosaur "teeth" from the Upper Cretaceous contained leucine(s), ammonia, ethanolamine, and one unidentified ninhydrin-reacting substance that chromatographed similarly to an unknown found in a hydrolysate of laboratory heated Mercenaria shells. Of the total-N in a shell of the univalve mollusc Casis Madagascarensis, 50 per cent was extractable with cold HCl, this fraction consisting of amino acids, ammonia and unidentified compounds, some of which reacted with ninhydrin. Only 57 per cent of the nitrogen in a hydrolysate of the conchiolinfraction of the shell was recovered in the form of amino acids and ammonia. Fifteen amino acids and two unknowns were detected in the hydrolysate of the conchiolin-fraction. The periostracum of a Pleistocene Mercenaria mercenaria shell liberated sixteen amino acids and three unidentified ninhydrin-reacting substances on acid hydrolysis. The periostracum-free fossil shell had approximately the same amino acid composition as reported elsewhere for shells of living Mercenaria. Quantitative data on amino acids and other ninhydrin-roacting compounds were reported for samples of Pleistocene Mercenaria shells pyrolysed in the laboratory at 213 and 219x000B0;C. In the shell, alanine decomposed at a faster rate, and plienylalanine at an equal or slower rate, than the rates characteristic of the same amino acids in dilute aqueous solution. The nitrogen liberated from amino acids during pyrolysis could mostly be accounted for in the hydrolysates as acid-insoluble-N, ammonia, and soluble nitrogenous compounds, some of which reacted with ninhydrin. Amines were detected only in samples pyrolysed in sealed tubes.

Electrode Processes of Nickel(II) Ions at the Mercury Electrode in Concentrated Calcium Chloride Solutions

Abstract A typical reduction wave with a half wave potential of −0.462 V. vs. S. C. E. was obtained with nickel(II) ions in 6 m calcium chloride solution. The a. c. and the Kalousek’s polarograms revealed that the electrode reaction is a quasi-reversible one. From the coulometric measurement carried out at the constant potential, the overall electrode reaction proved to be a two-electron reduction. Nearly the total amount of nickel reduced by the controlled potential electrolysis with the mercury electrode was recovered from the mercury, indicating that the nickel (II) ions are reduced to nickel metal to form probably nickel amalgam. From these experimental results the electrode reaction of nickel (II) ions in 6 m calcium chloride at the mercury electrode was concluded to proceed quasireversibly according to the equation Nicl_4^2-+2e+Hg\ightleftarrowsNi(Hg)+4Cl^-