scholarly journals ESTUDO DA CINÉTICA DE SECAGEM DE POLPAS DE HIDRÓXIDO DE MAGNÉSIO

e-xacta ◽  
2018 ◽  
Vol 11 (1) ◽  
pp. 119
Author(s):  
Elaine Cristina Campos ◽  
Diego Henrique de Souza Chaves ◽  
Lucas De Oliveira Souza ◽  
Matheus Andrade de Sousa ◽  
Marco De Souza Birchal ◽  
...  
Keyword(s):  
Magnesium Hydroxide ◽  
Physicochemical Characterization ◽  
Laser Diffraction ◽  
X Ray ◽  
Granulometric Analysis ◽  
Constant Rate ◽  
Kinetics Of ◽  
Different Sources ◽  
Caustic Magnesia

<p><em>O presente trabalho teve por objetivo estudar a cinética de secagem em estufa através da obtenção de dados de secagem de suas curvas e aplicação dos modelos matemáticos aplicados à secagem de polpas de hidróxido de magnésio preparadas a partir da hidratação de duas fontes distintas de magnésia cáustica e de uma polpa de hidróxido de magnésio p.a., a título de comparação. As polpas preparadas a partir das fontes de magnésia cáustica foram obtidas por hidratação do óxido de magnésio em um sistema híbrido reator-moinho de bolas após 5 horas de reação. Para caracterização físico-química das amostras, foram utilizadas as técnicas de fluorescência de raios X e análise granulométrica por difração a laser. Os resultados mostraram alta velocidade de secagem das polpas com a etapa de secagem à taxa constante como sendo a controladora do processo, com transferência de calor e massa predominantemente a partir da superfície, apresentando um melhor ajuste ao modelo de Lei de Resfriamento de Newton.</em></p><p><em> </em></p><p><em>ABSTRACT</em></p><p><em></em><em>The aim of the present work was to study the kinetics of drying in stove by obtaining drying data of its curves and applying the mathematical models applied to the drying of magnesium hydroxide pulps prepared from the hydration of two different sources of caustic magnesia and one magnesium hydroxide pulp, for comparison purposes. The pulps prepared from the sources of caustic magnesia were obtained by hydration of the magnesium oxide in a reactor-ball mill hybrid system after 5 hours of reaction. For the physicochemical characterization of the samples, the techniques of X-ray fluorescence and granulometric analysis by laser diffraction were used. The results showed a high drying rate of the pulps with the drying step at constant rate as the process controller, with heat transfer and mass predominantly from the surface, presenting a better fit to the Newton Cooling Law model.</em></p>

Purification of Bentonite Clays from Cubati, PB, Brazil, for Diversified Applications

2014 ◽  
Vol 805 ◽  
pp. 486-491
Author(s):  
J.M.R. Figueirêdo ◽  
Juliana Melo Cartaxo ◽  
I.A. Silva ◽  
C.D. Silva ◽  
Gelmires Araújo Neves ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Chemical Analysis ◽  
Laser Diffraction ◽  
The State ◽  
X Ray Diffraction ◽  
X Ray ◽  
Granulometric Analysis ◽  
Bentonite Clays

The State of Paraíba, Brazil, retains about 88.5% of all Brazilian bentonite, and much of this production comes from deposits in the District of Boa Vista, PB. Nevertheless, the deposits are almost depleted. Recently, new deposits were found, which will increases the reserves of the State, in the regions of Cubati and Pedra Lavrada, PB. The objective of this work is to characterize and develop purified clays, through sieving and hydrocycloning techniques, from those recently discovered bentonites for several applications. The characterization of the sample was done through granulometric analysis by laser diffraction, X-ray diffraction, chemical analysis by X-ray fluorescence, and thermogravimetric and differential thermal analysis. The results show that the samples are typical of bentonite clays, and that the purification solely by hydrocyclone presents the best results.

scholarly journals Assay and physicochemical characterization of the antiparasitic albendazole

2012 ◽  
Vol 48 (2) ◽  
pp. 281-290 ◽  
Author(s):  
Noely Camila Tavares Cavalcanti ◽  
Giovana Damasceno Sousa ◽  
Maria Alice Maciel Tabosa ◽  
José Lamartine Soares Sobrinho ◽  
Leila Bastos Leal ◽  
...  
Keyword(s):  
Physicochemical Characterization ◽  
Analytical Techniques ◽  
Assay Method ◽  
Active Pharmaceutical Ingredients ◽  
X Ray Diffraction ◽  
Melting Points ◽  
X Ray ◽  
Pharmaceutical Ingredients ◽  
Complementary Techniques

The aim of this study was to characterize three batches of albendazole by pharmacopeial and complementary analytical techniques in order to establish more detailed specifications for the development of pharmaceutical forms. The ABZ01, ABZ02, and ABZ03 batches had melting points of 208 ºC, 208 ºC, and 209 ºC, respectively. X-ray diffraction revealed that all three batches showed crystalline behavior and the absence of polymorphism. Scanning electron microscopy showed that all the samples were crystals of different sizes with a strong tendency to aggregate. The samples were insoluble in water (5.07, 4.27, and 4.52 mg mL-1, respectively) and very slightly soluble in 0.1 M HCl (55.10, 56.90, and 61.70 mg mL-1, respectively) and additionally showed purities within the range specified by the Brazilian Pharmacopoeia 5th edition (F. Bras. V; 98% to 102%). The pharmacopeial assay method was not reproducible and some changes were necessary. The method was validated and showed to be selective, specific, linear, robust, precise, and accurate. From this characterization, we concluded that pharmacopeial techniques alone are not able to detect subtle differences in active pharmaceutical ingredients; therefore, the use of other complementary techniques is required to ensure strict quality control in the pharmaceutical industry.

Characterization of chitin preparations using powder and film X-ray diffraction methods

2013 ◽  
Vol 28 (1) ◽  
pp. 44-48 ◽  
Author(s):  
Jeffrey R. Deschamps
Keyword(s):  
Diffraction Pattern ◽  
Purification Procedure ◽  
Limited Extent ◽  
X Ray Diffraction ◽  
X Ray ◽  
Naturally Occurring ◽  
Natural Polysaccharide ◽  
Different Sources

Chitin is a natural polysaccharide found in many diverse phyla and almost always occurs in association with protein. In this study the chitin polymer is characterized by X-ray diffraction from its naturally occurring unprocessed state through various steps used in the purification procedure. In addition, the effect of different treatments on the final product is examined. These studies show that native chitin has a characteristic diffraction pattern that is not altered by the mild treatments used to isolate relatively pure chitin. Chitins prepared from different sources exhibit the same characteristic diffraction pattern. In addition, chitin films prepared using non-degrading solvents retain most of the characteristic patterns. De-acylation of chitin to produce chitosan results in large changes to the diffraction pattern. To a very limited extent features present in the diffraction pattern of native chitin can be recovered by re-acylation of chitosan.

Effect of Laser Surface Modification on the Crystallinity of Poly(L-Lactic Acid)

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
Anubha Bhatla ◽  
Y. Lawrence Yao
Keyword(s):  
Lactic Acid ◽  
Polymer Surface ◽  
X Ray Diffraction ◽  
Factors Affecting ◽  
Laser Surface Modification ◽  
Third Harmonic ◽  
X Ray ◽  
Annealing Conditions ◽  
Kinetics Of

Crystallinity of semicrystalline polymers such as aliphatic homopolymer poly(L-lactic acid) (PLLA) affects their degradation and physical properties. In this paper, the effects of laser irradiation using the third harmonic of a Nd:YAG laser on the crystallinity, long-range order, and short-range conformations at the surface of PLLA films are investigated. The factors affecting the transformation are also studied. Detailed characterization of the effect of laser treatment is accomplished using microscopy, X-ray diffraction, and infrared spectroscopy. The cooling rates in the process and the spatial and temporal temperature profiles are numerically examined. The simulation results in conjunction with melting and crystallization kinetics of PLLA are used to understand the effect on sample crystallinity. The effects of laser fluence and annealing conditions on the crystallinity of the processed films are examined. Since degradation profiles depend on crystallinity, laser processing can potentially be used to achieve a modified spatially controlled polymer surface with promising applications such as controlled drug delivery.

Characterization of Nanocrystalline γ–Fe2O3Prepared by Wet Chemical Method

1999 ◽  
Vol 14 (4) ◽  
pp. 1570-1575 ◽  
Author(s):  
G. Ennas ◽  
G. Marongiu ◽  
A. Musinu ◽  
A. Falqui ◽  
P. Ballirano ◽  
...  
Keyword(s):  
Isothermal Treatment ◽  
X Ray Diffraction ◽  
Ferrous Chloride ◽  
Scanning Calorimetry ◽  
Direct Transformation ◽  
X Ray ◽  
Transmission Electron ◽  
Xrd Techniques ◽  
Kinetics Of

Homogeneous maghemite (γ–Fe2O3) nanoparticles with an average crystal size around 5 nm were synthesized by successive hydrolysis, oxidation, and dehydration of tetrapyridino-ferrous chloride. Morphological, thermal, and structural properties were investigated by transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and x-ray diffraction (XRD) techniques. Rietveld refinement indicated a cubic cell. The superstructure reflections, related to the ordering of cation lattice vacancies, were not detected in the diffraction pattern. Kinetics of the solid-state phase transition of nanocrystalline maghemite to hematite (α–Fe2O3), investigated by energy dispersive x-ray diffraction (EDXRD), indicates that direct transformation from nanocrystalline maghemite to microcrystalline hematite takes place during isothermal treatment at 385 °C. This temperature is lower than that observed both for microcrystalline maghemite and for nanocrystalline maghemite supported on silica.

Kinetics of lysozyme refolding: structural characterization of a non-specifically collapsed state using time-resolved X-ray scattering

1998 ◽  
Vol 276 (1) ◽  
pp. 225-237 ◽  
Author(s):  
Lingling Chen ◽  
Gudrun Wildegger ◽  
Thomas Kiefhaber ◽  
Keith O Hodgson ◽  
Sebastian Doniach
Keyword(s):  
Structural Characterization ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
Lysozyme Refolding ◽  
Kinetics Of ◽  
Ray Scattering

Electronic Waste: Characterization of the Glass of Cathode Ray Tube Computer for Making Decorative Pieces by Recycling

2012 ◽  
Vol 727-728 ◽  
pp. 1525-1529
Author(s):  
N.M.O. Lima ◽  
Crislene Rodrigues da Silva Morais ◽  
L.M.R. Lima ◽  
A.V. Albuquerque
Keyword(s):  
Electronic Waste ◽  
Modern World ◽  
Chemical Compositions ◽  
Strontium Oxide ◽  
X Ray Diffraction ◽  
X Ray ◽  
Granulometric Analysis ◽  
Cathode Ray Tube ◽  
Computer Monitors

The vigorous industrialization of the modern world and the incorporation of new consumption habits of society made appears electronic waste. This work had as objective to collect and characterize vitreous residues originating from Cathode Ray Tubes or, popularly, "image tubes", identified for the acronym CRT, which integrate computers monitors that will be recycled in the production of handicrafts. For its characterization were used techniques: X-Ray Fluorescence, Granulometric Analysis, X-Ray Diffraction. After analyses it was observed that glasses of the screen and of the funnel presented different chemical compositions, being silicium oxide (SiO2) the component of larger percentage in these glasses, 59.89% and 48.63%, for screen and funnel, respectively. Funnel presented 29.47% of lead oxide (PbO) while this oxide is absent in the screen. Screen presents significant amounts of barium oxide (10.75%) and strontium oxide (7.71%). Vitreous samples X-ray diffractions of residues of the funnel and the screen are to each other similar, presenting an amorphous band that indicates silica presence, with absence of crystalline phases. Through the presented results can be concluded that computer monitors CRTs has potential for be recycled, because present great amounts of SiO2, oxide that forms the vitreous net.

scholarly journals Characterization of the powder obtained from wasted tires reduced by pyrolysis and thermal shock process

2008 ◽  
Vol 6 (02) ◽  
Author(s):  
R. Mis-Fernandez ◽  
J.A. Azamar-Barrios ◽  
C.R. Rios-Soberanis
Keyword(s):  
Thermal Shock ◽  
Inorganic Compounds ◽  
Physicochemical Characterization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Shock Process ◽  
Carbon Compounds ◽  
The Relationship ◽  
Phase Production

This paper reports on the physicochemical characterization of solid powder obtained directly from wasted tires through pyrolysis and thermal shock process. Two different processes to reduce wasted tires were performed in order to acquire the residuals in powder to be characterized and compared.During this research, three phases were observed when pyrolysis was applied to rubber: the first one a solid black phase formed by organic and inorganic compounds such as zinc oxide (ZnO) and zinc sulphur (ZnS); secondly a gaseous phase containing hydrocarbons i.e. aromatic compounds and, finally, a liquid phase formed by heavy and light oils. By using X-ray diffraction technique, the relationship between temperature and the presence of inorganic compounds was determined varying the temperature of pyrolysis. In addition to X-ray diffraction, infrared spectroscopy, thermal analysis and scanning electron microscopy were used to fully characterize the samples. Comparing the results observed in both processes, it was found that thermal shock process presents some advantages over the pyrolytic, i.e. energy consume and solid black phase production; however, by pyrolytic egradation a powder richer in carbon compounds is obtained.

Sign in / Sign up

Export Citation Format

Share Document