Distinguishing Calcium Carbonate from Calcium Sulfate Dihydrate by Instrumental Methods. A Set of Laboratory Experiments for Analytical Chemistry and Spectroscopy

2001 ◽  
Vol 78 (8) ◽  
pp. 1090 ◽  
Author(s):  
Eugenio Garribba ◽  
Giovanni Micera ◽  
Angelo Panzanelli ◽  
Liliana Strinna-Erre ◽  
Giovanna Stara
Keyword(s):  
Analytical Chemistry ◽  
Calcium Carbonate ◽  
Calcium Sulfate ◽  
Laboratory Experiments ◽  
Calcium Sulfate Dihydrate ◽  
Instrumental Methods

scholarly journals First-principles study of calcium-based sulfur fixers and their products

2021 ◽  
pp. 350-350
Author(s):  
Guoyan Chen ◽  
Jianing Chen ◽  
Anchao Zhang ◽  
Haoxin Deng ◽  
Yanyang Mei ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Power Plant ◽  
Thermodynamic Properties ◽  
Calcium Oxide ◽  
First Principles ◽  
Calcium Sulfate ◽  
Density Functional ◽  
Stable State ◽  
Generalized Gradient ◽  
Calcium Sulphoaluminate

Calcium-based sulfur-fixing agent, as the main sulfur-fixing product, is widely used in power plant boiler systems. In order to further study the thermodynamic properties and reaction characteristics of calcium-based sulfur fixing agent and its products, the method of combining power plant experiment with theory was used. The electronic structure, thermodynamic properties and density of states of quicklime, limestone, calcium sulfate and calcium sulphoaluminate have been calculated based on the first-principles ultra-soft pseudopotential plane wave method of density functional theory. The generalized gradient approximation algorithm isused to optimize the structure of various minerals to achieve the most stable state. The results show that the enthalpy, entropy, specific heat capacity at constant pressure and Gibbs free energy of calcium sulfonate vary greatly from 25K to 1000K, while the change of calcium oxide is small, and that of calcium carbonate and calcium sulfate are between them. It shows that calcium sulphoaluminate has strong stability and more energy is needed to destroy the molecular structure of calcium sulphoaluminate. Calcium oxide is the most unstable and requires less energy to react; Calcium carbonate and calcium sulfate are in between. The variation range of calcium sulfate is greater than that of calcium carbonate, indicating that the stability of calcium sulfate is higher than that of calcium carbonate. The experimental results show that the desulfurization efficiency of generating calcium sulphoaluminate is much higher than that of only generating calcium sulfate, indicating that calcium sulphoaluminate is very stable, which is consistent with the calculated results.

scholarly journals The study of compositions based on parkent kaolin clay

2018 ◽  
pp. 29-33
Author(s):  
M. Kh. Rumi ◽  
Sh. K. Irmatova ◽  
M. A. Zufarov ◽  
Sh. A. Fayziev ◽  
E. P. Mansurova ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Liquid Glass ◽  
Calcium Sulfate ◽  
Kaolin Clay ◽  
Acid Activation ◽  
Kaolinite Clay ◽  
Aluminum Ions ◽  
Heat Treated ◽  
Rate Of Extraction ◽  
Subsequent Acid

The results of studies of the structure and composition of compositions based on red-burning kaolinite clay and calcium carbonate, heat-treated at 500oC, in the process of acid activation are presented. It is shown that when a 12 % solution of H2SO4is applied, leaching of iron and aluminum ions and the formation of calcium sulfate occur while maintaining the structure of kaolinite. The introduction of liquid glass into the composition of the material leads to the destruction of the structure of kaolinite, which contributes to an increase in the rate of extraction of aluminum ions during the subsequent acid activation. The components of the compositions with Ca2+and Fe3+in the presence of liquid glass are passivated by active amorphous silica formed during the reaction of liquid glass with CO2air.Ill. 2. Ref. 17. Tab. 1.

scholarly journals UMA PROPOSTA PARA O ENSINO DE LABORATÓRIO DE QUÍMICA ANALÍTICA QUALITATIVA

Química Nova ◽  
2020 ◽  
Author(s):  
Julia Postigo ◽  
Hellen Barbosa ◽  
Roberta Calefi ◽  
Jany Jesus ◽  
Priscila Cervini ◽  
...  
Keyword(s):  
Analytical Chemistry ◽  
Positive Feedback ◽  
Controversial Issue ◽  
Chemistry Teaching ◽  
Bottom Up ◽  
Teaching Laboratory ◽  
Methods Of Analysis ◽  
Experimental Step ◽  
Instrumental Methods

A PROPOSITION FOR TEACHING LABORATORY OF QUALITATIVE ANALYTICAL CHEMISTRY. Teaching laboratory of qualitative analytical chemistry is still a controversial issue in chemistry courses. However, important researchers and educators in chemistry recognized and highlighted the importance that the contents of this discipline represent in the formation of chemists, once it can provide handling and understanding of microscopic phenomena based on the observation of their macroscopic effects, once such reactions and phenomena are the basis of important instrumental methods of analysis. Thus, a proposal based on a bottom-up approach has been developed, starting with the observation of different reactions of cations in laboratory, followed by a search for the reaction responsible for each resulting phenomenon observed during the experimental step. Then these reactions are related with the separation procedures of each group of cations. Eventually the separation of these groups can also be performed depending on the time available. The proposal has been applied in teaching laboratory of qualitative analytical chemistry at Instituto de Química de São Carlos/USP since 2015, where the discipline is offered duirng 4 hours/week, and a positive feedback regarding the evolution of the methodology and its acceptance by students. Good results were also obtained concerning the appropriation of the contents by the students, using the proposal.

scholarly journals Scaling Risk Assessment in Nanofiltration of Mine Waters

Membranes ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 288
Author(s):  
Krzysztof Mitko ◽  
Ewa Laskowska ◽  
Marian Turek ◽  
Piotr Dydo ◽  
Krzysztof Piotrowski
Keyword(s):  
Calcium Sulfate ◽  
Flow Model ◽  
Membrane Surface ◽  
Mine Waters ◽  
Batch Mode ◽  
Single Pass ◽  
Calcium Sulfate Dihydrate ◽  
Dead End ◽  
In Series ◽  
Stirred Cell

Nanofiltration can be applied for the treatment of mine waters. One of the main problems is the risk of crystallization of sparingly soluble salts on the membrane surface (scaling). In this work, a series of batch-mode nanofiltration experiments of the mine waters was performed in a dead-end Sterlitech® HP 4750X Stirred Cell. Based on the laboratory results, the concentration profiles of individual ions along the membrane length in a single-pass industrial-scale nanofiltration (NF) unit was calculated, assuming the tanks-in-series flow model inside the membrane module. These calculations also propose a method for estimating the maximum achievable recovery before the occurrence of the calcium sulfate dihydrate scaling in a single-pass NF 40″ length spiral wound module, simultaneously allowing metastable supersaturation of calcium sulfate dihydrate. The performance of three membrane types (NF270, NFX, NFDL) has been evaluated for the nanofiltration of mine water.

Sign in / Sign up

Export Citation Format

Share Document