scholarly journals Concentric zoning patterns in crystallizing (Cd,Ca)CO3 solid solutions from aqueous solutions

1999 ◽  
Vol 63 (3) ◽  
pp. 331-343 ◽  
Author(s):  
Á. Fernández-González ◽  
M. Prieto ◽  
A. Putnis ◽  
S. López-Andrés
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Solid Solutions ◽  
Growth Process ◽  
Equilibrium Distribution ◽  
Reaction Path ◽  
Solid Phase ◽  
Equilibrium Partitioning ◽  
Compositional Zoning ◽  
Stoichiometric Proportion

AbstractOtavite-calcite solid solutions have been synthesized to investigate the factors which control the patterns of compositional zoning. The equilibrium partitioning of otavite between the aqueous and the solid phase can be described by means of a function XCdCO3(XCd,aq)eq, which relates the solid mole fraction and the aqueous activity fraction of Cd. According to this function, there is a strong preferential partitioning of Cd towards the solid. A set of experiments starting with parent solutions with different Cd2+/Ca2+ ratios was carried out. In these experiments nucleation takes place at high supersaturations and the Cd2+ and Ca2+ ions tend to be laid down in a ratio which deviates from the equilibrium distribution. Experimental nucleation data can be fitted to a curve XCdCO3(XCd,aq)ef of the same functionality as that for equilibrium.After nucleation, supersaturation decreases as the crystals grow. During this process, substituting ions are not incorporated into the solid in the same stoichiometric proportion as in the aqueous solution. Therefore, crystal and fluid compositions tend to vary as growth proceeds and this evolution is registered as a compositional zoning. The curves XCdCO3(XCd,aq)eq and XCdCO3(XCd,aq)ef confine the reaction path corresponding to the growth process. Here, these curves are used to account for the observed zoning patterns.

scholarly journals Impact of external physical effects on water and aqueous solutions: the problem of “memory”

2019 ◽  
Vol 59 (7) ◽  
pp. 1-16
Author(s):  
Ksenia A. Nurislamova ◽  
◽  
Alena S. Franz ◽  
Vyacheslav F. Markov ◽  
Larisa N. Maskaeva ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Electrical Conductivity ◽  
Aqueous Solutions ◽  
Solid Phase ◽  
Cluster Structure ◽  
Lead Salt ◽  
Physical Factors ◽  
Scientific Publications ◽  
Physical Effects ◽  
The Impact

A brief analysis of scientific publications on the changes in the physicochemical properties of water and aqueous solutions under the influence of temperature, magnetic and electric fields, laser and microwave radiation, ultrasound, and mechanical mixing was performed. A number of researchers have shown the influence of such effects on changes in pH and redox potential, electrical conductivity, surface tension and viscosity of an aqueous solution. The question of influence of external physical effects on water and aqueous solutions remains controversial. Some scientists suggest that water has a cluster structure, which is influenced by physical effects. An important aspect of the problem is the impact on the subsequent behavior and the final result of a chemical process involving previously treated aqueous solutions. Using water solutions of lead and thiourea as an example, the effect of their temperature prehistory in the range of 275-369 K on the kinetics of precipitation of the solid phase of lead sulfide and their microstructure is demonstrated. A threefold change in the composition of supersaturated CdxPb1–xS solid solutions precipitated from solutions containing a lead salt with different temperature prehistory was established. It is shown that the “memory” on the preliminary temperature effect is maintained for at least a day. The influence of electromagnetic treatment of water and aqueous solutions on the content of dissolved oxygen, pH and electrical conductivity is analyzed. Some scientists explain these results by the influence of the field on the structure of hydrogen bonds, others by a change in the cluster structure of water, as well as by the presence of ferromagnetic particles in water. The review presents the current state of the problem of the “memory” effect and the related influence of the prehistory of the impact of physical factors. The review suggested that the “memory” of an aqueous solution is the preservation for a certain time of the changes in its structure and properties that have arisen as a result of the effect. The basic ideas about the mechanisms of influence of the prehistory of physical effects on aqueous solutions are given.

Kinetics of the Decomposition of Sulphur Dicyanide in Aqueous Solution

1962 ◽  
Vol 15 (2) ◽  
pp. 211 ◽  
Author(s):  
W Kitching ◽  
RH Smith ◽  
IR Wilson
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Nucleophilic Substitution ◽  
Perchloric Acid ◽  
Reaction Path ◽  
Acid Solutions ◽  
Kinetics Of

The kinetics and stoicheiometry of the decomposition of aqueous solutions of sulphur dicyanide have been studied at temperatures between 0-70 �C and in media ranging from dilute perchloric acid to pH 7. The predominant reaction is nucleophilic substitution at carbon, but in perchloric acid solutions an alternative reaction path has been revealed.

The formation of rhodochrosite–smithsonite (MnCO3–ZnCO3) solid-solutions at 5°C

1995 ◽  
Vol 59 (396) ◽  
pp. 481-488 ◽  
Author(s):  
Michael E. Böttcher
Keyword(s):  
Aqueous Solution ◽  
Infrared Spectroscopy ◽  
Aqueous Solutions ◽  
Crystal Lattice ◽  
Powder Diffraction ◽  
Solid Solutions ◽  
Solubility Product ◽  
Experimental Conditions ◽  
X Ray ◽  
Bicarbonate Solutions

AbstractMnxZn(1−x)CO3 solid-solutions were prepared at 5°C by precipitation from metal-bearing bicarbonate solutions. The solids were identified by X-ray powder diffraction and infrared spectroscopy. Zn2+ ions substitute extensively for Mn2+ ions in the crystal lattice of anhydrous rhombohedral carbonates. Throughout the 24 h during which the experiments were conducted, the aqueous solutions remained undersaturated with respect to pure oxides, sulphates, hydroxides and hydroxysulphates. The solutions, however, were supersaturated with MnxZn(1−x)CO3 of any given composition. Besides the anhydrous rhombohedral carbonates, Zn4(OH)2(CO3)3·4H2O was precipitated from an aqueous solution with initially high Zn2+ concentration. The negative logarithm of the solubility product of Zn4(OH)2(CO3)3·4H2O was estimated theoretically to be 43.9 (25°C). Remaining saturation with respect to Zn4(OH)2(CO3)3·4H2O was calculated accordingly. The suggestion is made that hydrated zinc hydroxycarbonate is metastable under the experimental conditions used here, but that it should transform into anhydrous carbonates.

scholarly journals Acetylacetone functionalized magnetic carbon microspheres for the highly-efficient adsorption of heavy metal ions from aqueous solutions

RSC Advances ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 3337-3344 ◽  
Author(s):  
Jie Ma ◽  
Mengya Sun ◽  
Yulan Zeng ◽  
Zhenhua Liu ◽  
Manman Zhang ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Heavy Metal ◽  
Aqueous Solutions ◽  
Metal Ions ◽  
Heavy Metal Ions ◽  
Solid Phase ◽  
Carbon Microspheres ◽  
Highly Efficient ◽  
Magnetic Carbon

Herein, Acac-C@Fe3O4, a magnetic carbon (C@Fe3O4) modified with acetylacetone (Acac), was first prepared and used as a solid-phase adsorbent for adsorbing some heavy metal ions from aqueous solution.

Application of Silica Nanoparticles in the Determination of Herbicides in Environmental Water Samples Using Liquid Chromatography-Mass Spectroscopy

2020 ◽  
Vol 16 (5) ◽  
pp. 748-756
Author(s):  
Mir Waqas Alam ◽  
Tentu Nageswara Rao ◽  
Yarasani Prashanthi ◽  
Vourse Sridhar ◽  
Adil Alshoaibi ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Liquid Chromatography ◽  
Silica Nanoparticles ◽  
Solid Phase ◽  
Silica Nanoparticle ◽  
Environmental Water ◽  
Phase Extraction ◽  
Functionalized Nanoparticles ◽  
Supporting Material

Background: Herbicides are very beneficial in the crop yield with the aid of controlling weeds within the agriculture, but several herbicides are chronic in soil. Objective: In this study, nanoparticles and the packages of synthesized novel silica nanoparticles were studied for the preconcentration of herbicides. Methods: These nanoparticles prepared by the Stöber mechanism were purified and functionalized. Nanoparticles thus prepared successfully were used as supporting material for the preconcentration of residues of herbicides in the water. Results: Preconcentration was achieved by preparing the silica-based solid-phase-extraction cartridges. Nanoparticles used for this purpose were within the range of 50-250 nm. An SPE cartridge was prepared by packing 200 mg of silica nanoparticle in the empty cartridge of diameter 5.5 cm and length 0.6 cm in between PTFE frits. Aqueous solutions of 0.1 μg/ml of herbicides were prepared separately, and 10 ml of the solution was passed through the cartridge at the rate of 0.2 ml/min. After passing 10 ml volume of the aqueous solution, residues adsorbed on the cartridge were eluted using 2 ml of acetonitrile. The eluate was injected to determine the herbicide residue adsorbed on the SPE cartridge. Conclusion: In the study, it was found that greater than 90% of the herbicide residues were trapped on silica nanoparticle-based SPE cartridge. An analytical method was developed for the simultaneous determination of these herbicides. The residues were quantified by LC-MS/MS with ESI mode.

Effect of thermal history of aqueous solutions of KCl on the metastable zone width

1984 ◽  
Vol 49 (3) ◽  
pp. 559-569 ◽  
Author(s):  
Jaroslav Nývlt
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Thermal History ◽  
Equilibrium Solubility ◽  
Metastable Zone Width ◽  
Zone Width ◽  
Preceding Experiment ◽  
History Of ◽  
Metastable Zone ◽  
The Given

The metastable zone width of an aqueous solution of KCI was measured as a function of the time and temperature of overheating above the equilibrium solubility temperature. It has been found that when the experiments follow close upon one another, the parameters of the preceding experiment affect the results of the experiment to follow.The results are interpreted in terms of hypotheses advanced in the literature to account for the effect of thermal history of solution. The plausibility and applicability of these hypotheses are assessed for the given cause of aqueous solution of a well soluble electrolyte.

scholarly journals I. Thermo-electric behaviour of aqueous solutions with mercurial electrodes

1879 ◽  
Vol 29 (196-199) ◽  
pp. 472-482 ◽  
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Internal Diameter ◽  
Thermo Electric ◽  
Thin Glass ◽  
Mercury Surface

In order to investigate this subject, I devised and constructed the following apparatus :—A and B are two thin glass basins, 81 millims. internal diameter (= 5,153 sq. millims. of mercury surface), and 6·0 centims. deep; each containing a layer of mercury about 1·0 centim. deep, covered by a layer, about 3 centims. deep, of the aqueous solution to be examined.

Sign in / Sign up

Export Citation Format

Share Document