scholarly journals Alkaline Activation of Kaolin Group Minerals

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 268 ◽  
Author(s):  
Oliwia Biel ◽  
Piotr Rożek ◽  
Paulina Florek ◽  
Włodzimierz Mozgawa ◽  
Magdalena Król
Keyword(s):  
Sodium Hydroxide ◽  
Water Glass ◽  
Small Addition ◽  
Alkali Activation ◽  
Structural Studies ◽  
Structure And Properties ◽  
X Ray Diffraction ◽  
Bulk Materials ◽  
X Ray ◽  
Alkali Activated

Zeolites can be obtained in the process of the alkali-activation of aluminosilicate precursors. Such zeolite–geopolymer hybrid bulk materials merge the advantageous properties of both zeolites and geopolymers. In the present study, the effect of the type and concentration of an activator on the structure and properties of alkali-activated metakaolin, and metahalloysite was assessed. These two different kaolinite clays were obtained by the calcination of kaolin and halloysite, and then activated with sodium hydroxide and water glass. The phase compositions were assessed by X-ray diffraction, the microstructure was observed via scanning electron microscope, and the structural studies were conducted on the basis of the infrared spectra. The structure and properties of the obtained alkali-activated materials depend on both the type of a precursor and the type of an activator. The formation of zeolite phases was observed when the activation was carried out with sodium hydroxide alone, or with a small addition of water glass, regardless of the starting material used. The higher proportion of silicon in the activator solution does not give crystalline phases, but only an amorphous phase. Geopolymers based on metahalloysite have better compressive strength as the result of the better reactivity of metahalloysite compared to metakaolin.

New Rapid Setting Alkali Activated Cement Compositions

1989 ◽  
Vol 179 ◽  
Author(s):  
D. M. Roy ◽  
M. R. Silsbee ◽  
D. Wolfe-Confer
Keyword(s):  
Mechanical Property ◽  
Alkali Activation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Blended Cements ◽  
Setting Times ◽  
Rapid Setting ◽  
Alkali Activated ◽  
Alkali Activated Cement

AbstractThe advantage of utilizing blended cements for many applications has been well documented. However, the use of these materials has been limited by the longer setting times associated with the use of these materials. This report discusses the development of formulations employing alkali activation to shorten the setting times. The results of characterization of these materials using calorimetry, microscopic, x-ray diffraction, and mechanical property techniques are discussed.

Ribosome Structural Organization

1974 ◽  
Vol 32 ◽  
pp. 332-333
Author(s):  
James A. Lake
Keyword(s):  
Ribosomal Proteins ◽  
Structural Organization ◽  
Three Dimensional ◽  
Small Subunit ◽  
Structural Studies ◽  
X Ray Diffraction ◽  
Specific Antibodies ◽  
X Ray ◽  
E Coli ◽  
Complete Sequences

The understanding of ribosome structure has advanced considerably in the last several years. Biochemists have characterized the constituent proteins and rRNA's of ribosomes. Complete sequences have been determined for some ribosomal proteins and specific antibodies have been prepared against all E. coli small subunit proteins. In addition, a number of naturally occuring systems of three dimensional ribosome crystals which are suitable for structural studies have been observed in eukaryotes. Although the crystals are, in general, too small for X-ray diffraction, their size is ideal for electron microscopy.

scholarly journals Monitoring the course of early-age reactions in alkali activated aluminosilicates

2019 ◽  
Vol 282 ◽  
pp. 02056
Author(s):  
Miloš Jerman ◽  
Vratislav Tydlitát ◽  
Robert Černý
Keyword(s):  
Heat Flow ◽  
Sodium Hydroxide ◽  
Water Glass ◽  
Early Time ◽  
Early Age ◽  
Heat Power ◽  
Reaction Heat ◽  
Flow Calorimeter ◽  
Isothermal Heat Flow Calorimeter ◽  
Alkali Activated

In this paper the reaction heat development of alkali activated aluminosilicates is studied by an isothermal heat flow calorimeter. The highest reaction activity is observed during two hours after mixing. The hydration heat power at early time is influenced mainly by the composition of tested mixtures involving ceramic dust as precursor and different amounts of sodium hydroxide and water glass as activators and by temperature.

Sedimentary Clays as Geopolymer Precursor

2018 ◽  
Vol 39 ◽  
pp. 97-111
Author(s):  
F. Mostefa ◽  
Nasr Eddine Bouhamou ◽  
H.A. Mesbah ◽  
Salima Aggoun ◽  
D. Mekhatria
Keyword(s):  
Sodium Hydroxide ◽  
Mineralogical Composition ◽  
Cementitious Materials ◽  
Raw Material ◽  
X Ray Diffraction ◽  
Calcination Time ◽  
Calorimetric Analysis ◽  
X Ray ◽  
Before And After ◽  
Mechanical Performances

This work aims to study the feasibility of making a geopolymer cement based on dredged sediments, from the Fergoug dam (Algeria) and to evaluate their construction potential particularly interesting in the field of special cementitious materials. These sediments due to their mineralogical composition as aluminosilicates; are materials that can be used after heat treatment. Sedimentary clays were characterized before and after calcination by X-ray diffraction, ATG / ATD, spectroscopy (FTIR) and XRF analysis. The calcination was carried out on the raw material sieved at 80 μm for a temperature of 750 ° C, for 3.4 and 5 hours. The reactivity of the calcined products was measured using isothermal calorimetric analysis (DSC) on pastes prepared by mixing an alkaline solution of sodium hydroxide (NaOH) 8 M in an amount allowing to have a Na / Al ratio close to 1 (1: 1). Also, cubic mortar samples were prepared with a ratio L / S: 0.8, sealed and cured for 24 hours at 60 ° C and then at room temperature until the day they were submited to mechanical testing. to check the extent of geopolymerization. The results obtained allowed to optimize the calcination time of 5 hours for a better reactivity of these sediments, and a concentration of 8M of sodium hydroxide and more suitable to have the best mechanical performances.

Structural Studies on the Effects of ZrO[sub 2] Coating on LiCoO[sub 2] during Cycling Using In Situ X-Ray Diffraction Technique

2006 ◽  
Vol 153 (11) ◽  
pp. A2152 ◽  
Author(s):  
Kyung Yoon Chung ◽  
Won-Sub Yoon ◽  
James McBreen ◽  
Xiao-Qing Yang ◽  
Si Hyoung Oh ◽  
...  
Keyword(s):  
Structural Studies ◽  
X Ray Diffraction ◽  
X Ray

Structural studies by x-ray diffraction of model phospholipid-insulin membranes

Biochemistry ◽  
1972 ◽  
Vol 11 (6) ◽  
pp. 945-949 ◽  
Author(s):  
R. P. Rand ◽  
S. SenGupta
Keyword(s):  
Structural Studies ◽  
X Ray Diffraction ◽  
X Ray

scholarly journals Crystallographic and optical study of LiNb1 − xTaxO3

2017 ◽  
Vol 73 (3) ◽  
pp. 498-506 ◽  
Author(s):  
S. Huband ◽  
D. S. Keeble ◽  
N. Zhang ◽  
A. M. Glazer ◽  
A. Bartasyte ◽  
...  
Keyword(s):  
Phase Transition ◽  
Lithium Niobate ◽  
Lithium Tantalate ◽  
Flux Growth ◽  
Structural Studies ◽  
Optical Study ◽  
X Ray Diffraction ◽  
Growth Technique ◽  
X Ray ◽  
Li Content

Powders of lithium niobate-tantalate across the full compositional range have been made and crystals grown using a lithium vanadate flux growth technique. The Li-content of a lithium tantalate crystal has been determined using the zero-birefringence temperature and Curie measurements, confirming the Li content is between that of congruent and stoichiometric crystals. X-ray diffraction measurements show the Nb/Ta displacement and octahedral tilt both decrease as the Ta content is increased. This also results in a decrease in the lattice parameters from lithium niobate to lithium tantalate. Birefringence measurements on the crystals as a function of temperature have been used to determine the point that the crystals become zero-birefringent, and by comparison with the structural studies have confirmed that it is not related to a phase transition and the structures remain polar through the zero-birefringence points.

Nitroxide radicals appended to phthalonitriles: synthesis, structural characterization and photophysical properties

2021 ◽  
Vol 77 (3) ◽  
pp. 137-143
Author(s):  
Ismail Fidan ◽  
Emel Onal ◽  
Catherine Hirel
Keyword(s):  
Magnetic Measurements ◽  
Photophysical Properties ◽  
Nucleophilic Aromatic Substitution ◽  
Structural Studies ◽  
Aromatic Substitution ◽  
Nitronyl Nitroxide ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microwave Assisted ◽  
Ft Ir

The syntheses of 4-[4-(4,4,5,5-tetramethyl-2-imidazoline-3-oxide-1-oxyl-2-yl)phenoxy]phthalonitrile (3, C21H19N4O3) and 4-[4-(4,4,5,5-tetramethyl-2-imidazoline-1-oxyl-2-yl)phenoxy]phthalonitrile (4) were carried out by microwave-assisted nucleophilic aromatic substitution of 4-nitrophthalonitrile (2) by the pre-formed 2-(4-hydroxyphenyl)-4,4,5,5-tetramethyl-2-imidazoline-3-oxide-1-oxyl (1). Compounds 3 and 4 were characterized unambiguously by a rich array of analyses, such as melting point, FT–IR, MALDI–TOF MS, elemental analysis, UV–Vis, CV, EPR, magnetic measurements and single-crystal X-ray diffraction. Structural studies demonstrate that the C—H...X and C—X...π (X = O and N) interactions in the radical nitronyl nitroxide groups play an important role in the assembly of the crystal structures. Moreover, cyclic voltammetry analyses show that the phthalonitrile substituent retains the redox properties of the Ullman radicals.

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