Biogas and calcite handling in calcium fluoride precipitation from aqueous solution guided by thermodynamic simulation with PHREEQC

Thermodynamic Simulation of Essentuki Type Mineral Water Formation

E3S Web of Conferences ◽

10.1051/e3sconf/20199805012 ◽

2019 ◽

Vol 98 ◽

pp. 05012

Author(s):

Oxana A. Limantseva ◽

E.G. Potapov

Keyword(s):

Aqueous Solution ◽

Thermodynamic Modeling ◽

Dominant Role ◽

Thermodynamic Simulation ◽

Mineral Waters ◽

Solution Composition ◽

Cretaceous Rock ◽

Water Formation ◽

Carbon Dioxide Pressure ◽

Type Water

Thermodynamic models of Essentuki and Nagutsky fields of Caucasian Mineral Waters deposits (KMW) are developed. The models are based on laboratory studies of core samples of aptian-albian lower Cretaceous rock dissolution. The rock samples were disintegrated up to 0.25 mm grains. The rock grains were mixed with distilled or mineral waters and the mixtures were kept at 20-25°С and 65-70°С, carbon dioxide pressure of 4.04 MPa. The results of experimental and thermodynamic modeling are showed that aqueous solution composition formed, in particular, microcomponent concentrations, depends on the rock cement composition (clayey, calcic, siliceous, ferriferous, chloritic, zeolitic phosfatic, sulfatic or mixed) and on the percentage of the microelement mineral-bearing in the water-bearing rock. Also the aqueous solution composition depends on temperature and CO2 partial pressure in the silt - rain water CO2 system. Thermodynamic modeling of the system confirmed gypsum dominant role in sulfate type water formation against pyrite role.

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Thermodynamic simulation of li2co3 aqueous solution under fixed co2 pressures

The Journal of Chemical Thermodynamics ◽

10.1016/j.jct.2020.106334 ◽

2021 ◽

Vol 154 ◽

pp. 106334

Author(s):

M.N. Mamontov ◽

A.V. Gorbachev

Keyword(s):

Aqueous Solution ◽

Thermodynamic Simulation

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Chemische Stabilität von Natriummonofluorphosphat in der Porenlösung des Betons / Chemical stability of sodium monofluorophosphate in the pore solution of concrete

Restoration of Buildings and Monuments ◽

10.1515/rbm-1998-5293 ◽

1998 ◽

Vol 4 (4) ◽

pp. 423-434

Author(s):

A. Gerdes ◽

F. H. Wittmann

Keyword(s):

Aqueous Solution ◽

Calcium Phosphate ◽

Chemical Stability ◽

Calcium Fluoride ◽

Corrosion Inhibitors ◽

Pore Solution ◽

Concrete Surface ◽

Capillary Suction ◽

Soluble Calcium ◽

Non Destructive

Abstract For non-destructive rehabilitation in case of corroding reinforcement the application of sodium monofluorophosphate has been proposed. In practice an aqueous solution of sodium monofluorophosphate is sprayed on the concrete surface. By capillary suction the inhibitor is supposed to he transported into zones surrounding the corroding reinforcement in order to inhibit further corrosion. Hut the results presented here show that monofluorophosphate decomposes in the alkaline concrete pore solution forming slightly soluble calcium phosphate and calcium fluoride. Calcium phosphate and calcium fluoride are not known to work as corrosion inhibitors. The penetration depth in concrete depends on the properties of the microstructure and the rate of decomposition of sodium inonofluorophosphate. These mechanisms strongly limit the possible concentration near the reinforcement bars and, as a consequence, it is very unlikely to reach the level necessary to maintain the inhibition of corrosion in reinforced concrete.

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Structures Formed by Cryoprotective Agents Used in Freezc-Etching

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100066292 ◽

1971 ◽

Vol 29 ◽

pp. 448-449

Author(s):

G. G. Cocks ◽

C. E. Cluthe

Keyword(s):

Aqueous Solution ◽

Polyethylene Oxide ◽

Liquid Nitrogen Temperature ◽

Ice Crystals ◽

Etching Technique ◽

Structural Constituent ◽

Cryoprotective Agents ◽

Quick Freezing ◽

Freeze Etching ◽

Fractured Surface

The freeze etching technique is potentially useful for examining dilute solutions or suspensions of macromolecular materials. Quick freezing of aqueous solutions in Freon or propane at or near liquid nitrogen temperature produces relatively large ice crystals and these crystals may damage the structures to be examined. Cryoprotective agents may reduce damage to the specimem, hut their use often results in the formation of a different set of specimem artifacts.In a study of the structure of polyethylene oxide gels glycerol and sucrose were used as cryoprotective agents. The experiments reported here show some of the structures which can appear when these cryoprotective agents are used.Figure 1 shows a fractured surface of a frozen 25% aqueous solution of sucrose. The branches of dendritic ice crystals surrounded hy ice-sucrose eutectic can be seen. When this fractured surface is etched the ice in the dendrites sublimes giving the type of structure shown in Figure 2. The ice-sucrose eutectic etches much more slowly. It is the smooth continuous structural constituent surrounding the branches of the dendrites.

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Preparation and characterisation of vanadium pentoxide supported rhodium catalyst

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010010679x ◽

1988 ◽

Vol 46 ◽

pp. 946-947

Author(s):

A. Legrouri

Keyword(s):

Aqueous Solution ◽

Thermal Decomposition ◽

Physicochemical Properties ◽

Surface Area ◽

Vanadium Pentoxide ◽

High Purity ◽

Gas Adsorption ◽

Rhodium Catalyst ◽

Optical Methods ◽

Reducible Oxides

The industrial importance of metal catalysts supported on reducible oxides has stimulated considerable interest during the last few years. This presentation reports on the study of the physicochemical properties of metallic rhodium supported on vanadium pentoxide (Rh/V2O5). Electron optical methods, in conjunction with other techniques, were used to characterise the catalyst before its use in the hydrogenolysis of butane; a reaction for which Rh metal is known to be among the most active catalysts.V2O5 powder was prepared by thermal decomposition of high purity ammonium metavanadate in air at 400 °C for 2 hours. Previous studies of the microstructure of this compound, by HREM, SEM and gas adsorption, showed it to be non— porous with a very low surface area of 6m2/g3. The metal loading of the catalyst used was lwt%Rh on V2Q5. It was prepared by wet impregnating the support with an aqueous solution of RhCI3.3H2O.

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TEM observation of iron oxide pillars in montmorillonite

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100177544 ◽

1990 ◽

Vol 48 (4) ◽

pp. 882-883

Author(s):

H. Mori ◽

Y. Murata ◽

H. Yoneyama ◽

H. Fujita

Keyword(s):

Aqueous Solution ◽

Iron Oxide ◽

Fine Particles ◽

Aqueous Suspension ◽

Volume Ratio ◽

Exchange Capacity ◽

Nano Composites ◽

Pillared Montmorillonite ◽

Topographic Features ◽

Transmission Electron

Recently, a new sort of nano-composites has been prepared by incorporating such fine particles as metal oxide microcrystallites and organic polymers into the interlayer space of montmorillonite. Owing to their extremely large specific surface area, the nano-composites are finding wide application[1∼3]. However, the topographic features of the microstructures have not been elucidated as yet In the present work, the microstructures of iron oxide-pillared montmorillonite have been investigated by high-resolution transmission electron microscopy.Iron oxide-pillared montmorillonite was prepared through the procedure essentially the same as that reported by Yamanaka et al. Firstly, 0.125 M aqueous solution of trinuclear acetato-hydroxo iron(III) nitrate, [Fe3(OCOCH3)7 OH.2H2O]NO3, was prepared and then the solution was mixed with an aqueous suspension of 1 wt% clay by continuously stirring at 308 K. The final volume ratio of the latter aqueous solution to the former was 0.4. The clay used was sodium montmorillonite (Kunimine Industrial Co.), having a cation exchange capacity of 100 mequiv/100g. The montmorillonite in the mixed suspension was then centrifuged, followed by washing with deionized water. The washed samples were spread on glass plates, air dried, and then annealed at 673 K for 72 ks in air. The resultant film products were approximately 20 μm in thickness and brown in color.

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The microstructure of functionalized poLyacrylonitrile beads for bioseparations

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100178604 ◽

1990 ◽

Vol 48 (4) ◽

pp. 1094-1095

Author(s):

Eduardo A. Kamenetzky ◽

David A. Ley

Keyword(s):

Aqueous Solution ◽

Affinity Chromatography ◽

Pore Size Distribution ◽

Pore Size ◽

Surface Coverage ◽

Vacuum Impregnation ◽

Thin Sections ◽

Selective Staining ◽

Low Viscosity ◽

Diamond Knife

The microstructure of polyacrylonitrile (PAN) beads for affinity chromatography bioseparations was studied by TEM of stained ultramicrotomed thin-sections. Microstructural aspects such as overall pore size distribution, the distribution of pores within the beads, and surface coverage of functionalized beads affect performance properties. Stereological methods are used to quantify the internal structure of these chromatographic supports. Details of the process for making the PAN beads are given elsewhere. TEM specimens were obtained by vacuum impregnation with a low-viscosity epoxy and sectioning with a diamond knife. The beads can be observed unstained. However, different surface functionalities can be made evident by selective staining. Amide surface coverage was studied by staining in vapor of a 0.5.% RuO4 aqueous solution for 1 h. RuO4 does not stain PAN but stains, amongst many others, polymers containing an amide moiety.

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