Maghemite
Mostrando 1-12 de 48 artigos, teses e dissertações.
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1. New Magnetic Fe Oxide-Carbon Based Acid Catalyst Prepared from Bio-Oil for Esterification Reactions
In this work, bio-oil (an organic matrix rich in oxygen functionalities) was used to efficiently dissolve and disperse Fe3+ which upon thermal treatment produced a carbon containing dispersed and encapsulated Fe oxide magnetic nanoparticles. These materials were prepared by dissolution of 8, 16 and 24 wt.% Fe3+ salt in bio-oil followed by treatment at 400, 4
J. Braz. Chem. Soc.. Publicado em: 2020-08
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2. Mineralogical Evolution of Magnetic Rhodic Oxisols under Different Lithological Influences in Brazil
ABSTRACT Ferrimagnetic Fe-oxides are important soil components, which are present in most of the agricultural soils of Brazil. Distinction, origin, and assessment of the influence of these minerals on magnetism and geochemistry is a challenge for mineralogists. This study aimed to characterize mineralogically Fe-rich Rhodic Oxisols ( Latossolos Vermelhos ) o
Rev. Bras. Ciênc. Solo. Publicado em: 30/09/2019
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3. OPTIMIZATION OF LIPASE IMMOBILIZATION ON MAGHEMITE AND ITS PHYSICO-CHEMICAL PROPERTIES
ABSTRACT Nanomaterial-based biocatalysts have emerged as current carriers suitable for enzyme immobilization. The nano-sized materials provide large surface area for enzyme attachment, thus increasing the probability for its efficient catalyst activity. By using magnetized nanomaterials, enhancement of the downstream processing is evident as it eases the imm
Braz. J. Chem. Eng.. Publicado em: 15/07/2019
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4. Green polyurethane synthesis by emulsion technique: a magnetic composite for oil spill removal
Abstract After the consolidation of the Brazilian biodiesel industry, issues related to the final destination of the glycerin, the by-product from the biodiesel industrial process, drawing the attention of several researchers. There are several uses to this byproduct. Among them, the obtaining of polymers, such as polyurethane (PU), are very encouraged since
Polímeros. Publicado em: 2017-12
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5. Kinetics of Thermal Transformation of Synthetic Al-Maghemites into Al-Hematites
ABSTRACT Maghemite (γ-Fe2O3) and hematite (α-Fe2O3) are important iron oxides in Brazilian soils derived from basalt. Maghemite can transform into hematite when exposed to high temperatures. However, isomorphic substitution (e.g., Al3+) may largely influence this process. We analyzed the kinetics of thermal transformation of Al-maghemites into Al-hematites
Rev. Bras. Ciênc. Solo. Publicado em: 27/04/2017
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6. Pedogenic Iron Oxides in Iron-Rich Oxisols Developed from Mafic Rocks
ABSTRACT Despite the considerable amount of information on the mineralogical characteristics of pedogenic Fe oxides in Brazilian soils, there are few studies on Fe-rich soils developed from mafic rocks with taxonomic identities at lower categorical levels. This study evaluated the mineralogical characteristics of pedogenic Fe oxides in B horizons (Bw) of Fe-
Rev. Bras. Ciênc. Solo. Publicado em: 27/04/2017
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7. Characterization and Chemical Stability of Hydrophilic and Hydrophobic Magnetic Nanoparticles
Magnetic nanoparticles can improve the efficiency of phase separation time in multi-stage operations when a magnetic field is present. As such operations involve contact with aqueous and/or organic solutions, hydrophilic magnetic nanoparticles synthesized through the co-precipitation method were functionalized with oleic acid to attain hydrophobic magnetic n
Mat. Res.. Publicado em: 10/04/2017
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8. Chemical-Mineralogical Characterization of Magnetic Materials from Magnetic Soils of the Southern Espinhaço Mountain Chain and of the Upper Jequitinhonha Valley, State of Minas Gerais, Brazil
ABSTRACT In the Southern Espinhaço Mountain Chain and in the Upper Jequitinhonha Valley, magnetic soils, in different pedogenetic stages, are found to be forming over intrusions of basic lithology. The essential chemical and mineralogical properties of samples from magnetic soil profiles from those two physiographic environments in the state of Minas Gerais
Rev. Bras. Ciênc. Solo. Publicado em: 27/03/2017
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9. A Mesoporous SiO2/γ-Fe2O3/KI Heterogeneous Magnetic Catalyst for the Green Synthesis of Biodiesel
A magnetic catalyst (sample MCat) consisting of KI supported on a mixture of silica and maghemite (γ-Fe2O3) was prepared and used in the transesterification reaction for the synthesis of biodiesel. The energy dispersive X-ray spectrum of the catalyst showed signals due to Si, Fe, K, and I. Powder X-ray diffraction data revealed the amorphous nature of the S
J. Braz. Chem. Soc.. Publicado em: 2016-12
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10. Thermal Transformation and Characterization of Synthetic Al-Substituted Maghemites (γ-Fe2-xAlxO3)
ABSTRACT Burning is a common practice in tropical areas and related changes in mineralogy might affect the chemical and physical behavior of soils. Maghemite is a common iron oxide in soils formed from basic rocks in tropical regions. This mineral and hematite are the main pigments in these soils and exhibit high magnetization stemming from the precursor mag
Rev. Bras. Ciênc. Solo. Publicado em: 03/11/2016
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11. Study of Thermal Degradation of PLGA, PLGA Nanospheres and PLGA/Maghemite Superparamagnetic Nanospheres
Poly(glycolide-co-lactide) (PLGA) nanospheres containing magnetic materials have been extensively studied because of its biomedical applications. Therefore, it is very important to know thermal properties of these materials in addition to other physical properties. Thermal degradation activation energy (Eα) of PLGA nanospheres with maghemite entrapment (PLG
Mat. Res.. Publicado em: 24/11/2015
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12. Synthesis, Characterization and Applications of Iron Oxide Nanoparticles - a Short Review
ABSTRACT: Iron oxide is a mineral compound that shows different polymorphic forms, including hematite (α-Fe2O3), magnetite (Fe3O4) and maghemite (γ-Fe2O3). Solid propulsion technology nanoparticulate materials, such as hematite and maghemite, exhibit high performance on thermal decomposition of ammonium perchlorate. The enhanced catalytic effect of metalli
J. Aerosp. Technol. Manag.. Publicado em: 2015-09