Mimetite Formation from Goethite-Adsorbed Ions

2016 ◽  
Vol 22 (3) ◽  
pp. 698-705 ◽  
Author(s):  
Anna Kleszczewska-Zębala ◽  
Maciej Manecki ◽  
Tomasz Bajda ◽  
John Rakovan ◽  
Olaf J. Borkiewicz
Keyword(s):  
Contaminated Soils ◽  
X Ray Diffraction ◽  
Electron Backscattered Diffraction ◽  
Rapid Crystallization ◽  
X Ray ◽  
Heterogeneous Precipitation ◽  
Homogeneous Crystallization ◽  
Kinetics Of ◽  
Saturation Front ◽  
Scanning Electron

AbstractBioavailability of arsenic in contaminated soils and wastes can be reduced to insignificant levels by precipitation of mimetite Pb5(AsO4)3Cl. The objective of this study is to elucidate mechanisms of the reaction between solution containing lead ions and arsenates adsorbed on synthetic goethite (AsO4-goethite), or arsenate ions in the solution and goethite saturated with adsorbed Pb (Pb-goethite). These reactions, in the presence of Cl, result in rapid crystallization of mimetite. Formation of mimetite is faster than desorption of AsO4 but slower than desorption of Pb from the goethite surface. Slow desorption of arsenates from AsO4-goethite results in heterogeneous precipitation and formation of mimetite incrustation on goethite crystals. Desorption of lead from Pb-goethite is at least as fast as diffusion and advection of AsO4 and Cl in suspension allowing for homogeneous crystallization of mimetite in intergranular solution. Therefore, the mechanism of nucleation is primarily driven by the kinetics of constituent supply to the saturation front, rather than by the thermodynamics of nucleation. The products of the reactions are well documented using microscopy methods such as scanning electron microscopy, electron backscattered diffraction, X-ray diffraction, and Fourier transform infrared spectroscopy.

Thermal Decomposition Kinetics of Ammonium Aluminum Carbonate Hydroxide

2008 ◽  
Vol 368-372 ◽  
pp. 1577-1579
Author(s):  
Hai Jun Zhang ◽  
En Xia Xiu ◽  
Xiu Juan Wang ◽  
Quan Li Jia ◽  
Hong Wei Sun ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thermal Decomposition ◽  
Preexponential Factor ◽  
Decomposition Kinetics ◽  
Algebraic Expression ◽  
X Ray Diffraction ◽  
X Ray ◽  
Carbonate Hydroxide ◽  
Kinetics Of ◽  
Scanning Electron

The thermal decomposition of ammonium aluminum carbonate hydroxide was studied under non-isothermal conditions in air. The decomposition kinetics were evaluated from data of TG-DTA by means of the Kissinger equation and the Coats-Redfern equation. The values of the activation energy E, the preexponential factor A and the algebraic expression of integral G(α) functions of the thermal decomposition were calculated. The ammonium aluminum carbonate hydroxide (AACH) was characterized by X-ray diffraction, differential thermal analysis and thermogravimetric and field emission scanning electron microscopy.

Study and Properties of a Steel Microalloyed Hardened Superficially

2015 ◽  
Vol 365 ◽  
pp. 122-127 ◽  
Author(s):  
N. López-Perrusquia ◽  
M.A. Doñu Ruiz ◽  
C. R. Torres San-Miguel ◽  
M. Flores-Báez ◽  
I. Flores-Báez
Keyword(s):  
Growth Process ◽  
Energy Dispersive Spectrometry ◽  
Boride Layer ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffusion Controlled ◽  
Boriding Process ◽  
Kinetics Of ◽  
Over Time ◽  
Scanning Electron

In this study, we present a boronizing treatment on a steel microalloy that was performed according to dehydrated paste-pack boriding. The temperatures conducted were at 1173, 1223 and 1273 K; at various exposure times of 1, 3, 6 and 9 h. As a result of the boriding process, diffusion-controlled growth of the FeB/Fe2B layers was obtained at the surface of the micro-alloy steel, and the kinetics of the growth process changed parabolically over time. The results of these examination properties of the boride layer as revealed by Optical Microscopy (OP) showed the morphology of the boride layer as a saw-tooth with a thickness ranging from 33 μm to 220 μm depending on the boronizing time. The analysis of Scanning Electron Microscopy (SEM-EDS); showed a distribution of the alloying elements that were detected by Energy Dispersive Spectrometry. The X-ray diffraction (XRD) technique indicated that the surface was a mixture of FeB and Fe2B borides. The evaluation of adhesion of the layers was determined by the technique of Rockwell-C hardness. Young’s modulus and hardness of the layer were evaluated by a nanoindentation technique with a load of 250 mN. The paste dehydrate boriding of micro-alloy reveal a change of properties on the surface; also the coatings FeB and Fe2B, to make a sacrificial function in the steels micro alloyed as widely used in pipelines transporting oil.

scholarly journals Synthesis and Characterization of Erythromycin Loaded PLGA and PCL Microspheres: Antimicrobial Application

2021 ◽  
Author(s):  
Lamia Bennabi ◽  
Ilham Abedelemalek ◽  
Abedelkader Ammari ◽  
Khaldia Sediri ◽  
Fatima Bennabi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Glycolic Acid ◽  
Release Kinetics ◽  
Synthesis And Characterization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Complementary Effect ◽  
Kinetics Of ◽  
Scanning Electron

Abstract We presents in this work the preparation of several formulations, based on biocompatible biodegradable polymers: polycaprolactone (PCL) and poly(lactic-co-glycolic) acid (PLGA) loaded with Erythromycin (ERYT) antibiotic. These biocompatible materials were used to prepare microspheres with and without immobilized ERYT via simple evaporation method by simple emulsion. The particle size was determined by scanning electron microscopy and the absence of the interaction with ERYT was confirmed via X-ray diffraction and infrared spectroscopy. The release kinetics of ERYT were studied and then, ERYT loaded PCL and PLGA blends microspheres were used for the inhibition of gram-positive S. aureus strain. The microbial activity was carried-out by Agar diffusion disc method. The results show that PCL/PLGA blend and PCL alone inhibited the strain by ERYT present in kinetic aliquots with the complementary effect of the polymers. A numerical model was proposed for modeling the kinetics reported in our study.

The Effect of Deformation and Irradiation with High-Energy Krypton Ions on the Structure and Phase Composition of Reactor Steels

2013 ◽  
Vol 702 ◽  
pp. 88-93
Author(s):  
Alyona Russakova ◽  
Darya Alontseva ◽  
Tatyana Kolesnikova
Keyword(s):  
High Energy ◽  
X Ray Diffraction ◽  
Electron Backscattered Diffraction ◽  
X Ray ◽  
Α Phase ◽  
Scale Levels ◽  
Reactor Steels ◽  
Analysis Application ◽  
Ebsd Method ◽  
Scanning Electron

The paper presents some results of a complex research of 12Cr18Ni10Ti stainless steel in the initial, deformed and irradiated ( 8436Kr+14, E=130MeV, Fmax=9x1015 ions/сm2) states using magnetometry, X-ray diffraction (XRD) and scanning electron microscopy (SEM) with electron backscattered diffraction (EBSD – analysis). Application of the EBSD method revealed differences between the non-irradiated and irradiated 12Cr18Ni10Ti steel specimens consisting in the fact that in the surface layer of an irradiated sample α-and ε - phases are formed. It was established that the fluence value affects the amount of magnetic α-phase. The study of the martensite α-phase morphology showed that in the deformed steel specimens there is αʹ- martensite of two scale levels.

scholarly journals Effect of the Porosity, Roughness, Wettability, and Charge of Micro-Arc Coatings on the Efficiency of Doxorubicin Delivery and Suppression of Cancer Cells

Coatings ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 664
Author(s):  
Mariya Borisovna Sedelnikova ◽  
Ekaterina G. Komarova ◽  
Yurii P. Sharkeev ◽  
Valentina V. Chebodaeva ◽  
Tatiana V. Tolkacheva ◽  
...  
Keyword(s):  
Calcium Phosphate ◽  
X Ray Diffraction ◽  
Oxidation Method ◽  
X Ray ◽  
Phosphate Coatings ◽  
Micro Arc Oxidation ◽  
Calcium Phosphate Coatings ◽  
Adsorption Desorption ◽  
Kinetics Of ◽  
Scanning Electron

Porous calcium phosphate coatings were formed by the micro-arc oxidation method on the surface of titanium for the loading and controlled release of the anticancer drug doxorubicin. The coatings’ morphology and microstructure were examined by scanning electron microscopy. The phase composition was determined with the help of X-ray diffraction analysis. Studies of the hydrophilic properties of the coatings and their zeta potential were carried out. Data on the kinetics of doxorubicin adsorption-desorption were obtained. In addition, the effect of calcium phosphate coatings impregnated with doxorubicin on the viability of the Neuro-2a cell line was revealed. The coating formed at low voltages of 200–250 V contained a greater number of branched communicating pores, and therefore they were able to adsorb a greater amount of doxorubicin. The surface charge also contributes to the process of the adsorption-desorption of doxorubicin, but this effect is not fully understood and further studies are required to identify it.

Microstructural Evolution during Forging of Ti-6Al-4V Alloy

2016 ◽  
Vol 849 ◽  
pp. 251-258 ◽  
Author(s):  
Lu Yao Tang ◽  
Jin Shan Li ◽  
Hong Chao Kou ◽  
Xu Yan ◽  
Bin Tang ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Pole Density ◽  
High Angle ◽  
X Ray Diffraction ◽  
Electron Backscattered Diffraction ◽  
X Ray ◽  
Forging Process ◽  
Textural Evolution ◽  
Α Phase ◽  
Scanning Electron

In this work, a 1600 tons forging machine was employed to conduct forging on the Ti-6Al-4V alloy. The microstructural and textural evolution of forged alloy were investigated by optical microscopy (OM), scanning electron microscopy (SEM), electron backscattered diffraction technique (EBSD) and X-ray diffraction (XRD). The results showed that the lamellar α phase in the Ti-6Al-4V alloy changed into a spherical morphology, and the spheroidization rate and the structure uniformity increased with the increasing forging times. The largest pole density in each incomplete pole figure of the α phase decreased gradually and the high-angle grain boundaries (HAGBs) gradually turned to the low-angle grain boundaries (LAGBs), which indicated that the texture was reduced during the forging process.

Influence of Power and Synthesis Time in the Formation of Mullite Obtained by Microwave Heating

2015 ◽  
Vol 820 ◽  
pp. 90-95 ◽  
Author(s):  
Lisiane Navarro de Lima Santana ◽  
Josileido Gomes ◽  
Valmir José da Silva ◽  
Wherllyson Patrício Gonçalves ◽  
Hélio de Lucena Lira ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Microwave Heating ◽  
Rapid Heating ◽  
X Ray Diffraction ◽  
Synthesis Time ◽  
X Ray ◽  
Mullite Phase ◽  
Kinetics Of ◽  
Scanning Electron

Front of the large number of applications of the mullite mineral, many researchers seek to synthesize it from the mixture of Al2O3and SiO2powders, or from aluminossilicates, such as smectite. The synthesis of mullite from clays via rapid heating by microwaves emerges as an alternative process. This process accelerates the kinetics of nucleation and the development of mullite phase. Thus, the aim of this work is to study the effect of power and timeon synthesis of mullite from clay, via rapid heating in microwave. The synthesis times were 15 and 20 minutes, with powers of 1.26 and 1.44kW. The obtained powderswere characterized by X-ray diffraction and scanning electron microscopy. The best results were obtained with a power of 1.44kW for 20 minutes.

Oxidation Behaviour of WE54 and Elektron 21 Magnesium Alloys

2011 ◽  
Vol 312-315 ◽  
pp. 483-488 ◽  
Author(s):  
Andrzej Kiełbus ◽  
Tomasz Rzychoń ◽  
Roman Przeliorz
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Oxidation Kinetics ◽  
Oxidation Behaviour ◽  
X Ray Diffraction ◽  
X Ray ◽  
Parabolic Law ◽  
Supersaturated State ◽  
Kinetics Of ◽  
Scanning Electron

In the present study, the isothermal early oxidation behaviour of the WE54 and Elektron 21 alloys were studied at a temperature of 773 K in pure O2 up to 150 min. The results showed that the oxidation kinetics depending on the chemical composition and microstructure of the investigated alloys. The oxidation kinetics of these alloys in as-cast and T6 conditions obtained a parabolic law, while in supersaturated state these alloys exhibited a linear kinetics. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses indicated that an oxide film, composed of MgO and (Y,Dy)2O3 in WE54 alloy and (Nd,Gd)2O3 in Elektron 21 alloy, had been formed.

The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

1973 ◽  
Vol 31 ◽  
pp. 132-133 ◽  
Author(s):  
R. E. Herfert
Keyword(s):  
Surface Characterization ◽  
Analytical Techniques ◽  
X Ray Diffraction ◽  
Depth Of Penetration ◽  
X Ray ◽  
The Past ◽  
Transmission Electron ◽  
Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

Identification of calcium oxalate crystals in dried or fixed tobacco leaf

1984 ◽  
Vol 42 ◽  
pp. 288-289
Author(s):  
Vicki L. Baliga ◽  
Mary Ellen Counts
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Calcium Oxalate ◽  
Growth And Development ◽  
Polarized Light ◽  
Calcium Oxalate Crystals ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Electron

Calcium is an important element in the growth and development of plants and one form of calcium is calcium oxalate. Calcium oxalate has been found in leaf seed, stem material plant tissue culture, fungi and lichen using one or more of the following methods—polarized light microscopy (PLM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and x-ray diffraction.Two methods are presented here for qualitatively estimating calcium oxalate in dried or fixed tobacco (Nicotiana) leaf from different stalk positions using PLM. SEM, coupled with energy dispersive x-ray spectrometry (EDS), and powder x-ray diffraction were used to verify that the crystals observed in the dried leaf with PLM were calcium oxalate.

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