The competing effect of ammonia in the synthesis of iron oxide/silica nanoparticles in microemulsion/sol–gel system

Fernandes, Maria Tereza Cortez; Garcia, Renata Batista Rivero; Leite, Carlos A. P.; Kawachi, Elizabete Yoshie

doi:10.1016/j.colsurfa.2013.01.025

Cited by 28 publications

(11 citation statements)

References 17 publications

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“…Iron oxide and compositei ron oxide/silicap owders were synthesized as described elsewhere [11].T able 1p resents the composition of the MEs used as synthetic systems. Non-encapsulatedi ron oxide samples with different surface areas (identified as F 1 and F 2 )a nd composite iron oxide/ silica (identified as FS) samples werep reparedb yd ropping 20.0 mL of ME 1b into ME 1a or ME 2b into ME 2a ,r espectively, under magnetic stirring.A ll mixtures were then sonicated (Marconi, 30 %a mplitudea nd cycleo f0 .2) for 30 min.…”

Section: Microemulsion (Me) Synthesismentioning

confidence: 99%

“…For the samples as synthesized (F 1 ,F 2 and FS), bandsa round 1550 and 1400 cm À1 are due to organicr esiduesf rom the microemulsion synthesis, mainly the surfactant that strongly absorbs over the high surface area of the particles [11].T hese impurities are observed by all FT-IR techniques, indicating that the organicr esidues spread over the samples in at hick layer.H eatingi nduced the decomposition of this organic residue,l eaving no indication of impurities in the sample's FS 500 spectra. It is interesting to note that the transmission spectrum for the commercial F C sample shows only iron oxide bands, whilstD RIFT and UATR spectra also show bands around 1100 to 800 cm À1 ,w hich may indicate that the iron oxide particles are covered with av ery thin protective layer,n ot informed by the provider.…”

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confidence: 97%

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Chemical and Textural Characterization of Iron Oxide Nanoparticles and Their Effect on the Thermal Decomposition of Ammonium Perchlorate

Campos

Fernandes

Kawachi

et al. 2015

Propellants Explo Pyrotec

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[a] 1IntroductionIron oxide-based materials have been of greatt echnological importance for al ong time. Even though, they still attract attention, especially in the form of nanoparticleso r nanocomposites, due to their unique magnetic, optical and catalytic properties [1][2][3].A lthough al arge number of crystalline phases are knownf or iron oxides,h ydroxides and oxy-hydroxides [4],a morphous iron oxide nanoparticles are more active than theirr elated nanocrystalline polymorphs, due to the highers urface-to-volume ratio and high surface energy in the amorphous phase [3,5],b eing much more interesting for catalytic applications.In composite solid propellants,A Pi st he most used oxidizer and its thermald ecomposition is strongly affected by the presence of metal oxide additives. In particular, Fe 2 O 3 is believed to act as catalyst in the gas-phase reactions that take place during the decomposition process of AP.T hus, the catalyst'sc oncentration, its specific surface area, particle size and state of agglomeration will be of great influence over AP thermald ecomposition [6,7].Many papers have demonstrated that nanoparticles of different natures show higher catalytic efficiency than microsizedp articles [6,[8][9][10].T herein authors associate this efficiency to both size and morphology of the catalytic particles, but few of them either determine or compare the textural properties of the studied catalysts. Nonetheless, due to theirh igher surface energy,p articles in nanometric scale are pronet oa gglomeration and, unless this process is completelya voided, it is not always true that the size and Abstract:M etal oxide nanoparticles have beenu sed as burning rate catalysts for ammonium perchlorate (AP) decomposition in composite solid propellants. Though most papers point to the efficiencyo fd ifferent sizes, shapesa nd compositions,t he texture of the agglomerated particles plays an important role in the catalytic efficiency,b ut this aspect is not always discussed. In this paper,i ron oxide and composite iron oxide/silica powders were synthesized in microemulsion systems and their effect on the decomposition of AP was investigated.X -ray diffraction (XRD) analysis and Fourier transformed infrared spectroscopy (FT-IR) showed that the synthesizedp owders havea na morphous to nanocrystalline pattern,w ith Fe 2 O 3 composition.T he use of different FT-IR spectroscopic techniques -t ransmission, diffuse reflectance (DRIFT)a nd universal attenuated total reflectance (UATR) -a llied to electron microscopy analysis allowed the characterizationo ft he samples' surface, indicating that silicon oxide formsathickm atrixt hat covers the iron oxide nanoparticles.A dsorption of N 2 ,l ight scattering and electron microscopy pointed that all samples are formedb ym esoporous agglomerated nanoparticles containing micropores indicating that silicon oxide forms at hick matrix that covers the iron oxide nanoparticles. Adsorption of N 2 ,p ointed that all samples show different microstructures and light scattering indicated re...

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Section: Microemulsion (Me) Synthesismentioning

confidence: 99%

mentioning

confidence: 97%

Chemical and Textural Characterization of Iron Oxide Nanoparticles and Their Effect on the Thermal Decomposition of Ammonium Perchlorate

Campos

Fernandes

Kawachi

et al. 2015

Propellants Explo Pyrotec

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“…It can be achieved by using different methods which consist of hydrolysis of alcoxysilane as tetraethoxysylane (TEOS) (Fernandes et al 2013;Teja and Koh 2009;Laurent and Mahmoudi 2011), in the presence of ammonia and superparamagnetic iron oxide nanoparticles. This precursor with the formula Si(OC 2 H 5 ) 4 contains four ethyl groups attached to SiO 4 , which is called orthosilicate (Fernandes et al 2013).…”

Section: Microemulsionmentioning

confidence: 99%

“…The preparation of magnetic iron oxide nanoparticles with controlled size and morphology has been carried out in water-in-oil microemulsion consisting of a cationic or non-ionic surfactant (Triton-X), a co-surfactant (glycols, hexanol, 1-butanol), oil phase (n-octane, cyclohexane) and aqueous phase (Fernandes et al 2013). The microemulsion is formed through addition of an aqueous solution with iron salt precursors to the surfactant/co-surfactant mixture.…”

Section: Microemulsionmentioning

confidence: 99%

Synthesis, Characterization and Applications of Iron Oxide Nanoparticles - a Short Review

Campos

Pinto

Oliveira

et al. 2015

J.Aerosp. Technol. Manag.

201

100

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Iron oxide is a mineral compound that shows different polymorphic forms, including hematite (α-Fe 2 O 3 ), magnetite (Fe 3 O 4 ) and maghemite (γ-Fe 2 O 3 ). Solid propulsion technology nanoparticulate materials, such as hematite and maghemite, exhibit high performance on thermal decomposition of ammonium perchlorate. The enhanced catalytic effect of metallic iron oxide nanoparticles is attributed to their particle size, more active sites and high surface area, which promotes more gas adsorption during thermal oxidation reactions. Nowadays, metallic iron nanoparticles can be synthesized via numerous methods, such as co-precipitation, sol-gel, microemulsion, or thermal decomposition. Although there are data on these synthetic methods in the literature, there is a lack of details related to nanoparticulate oxides and to their characterization techniques. In this context, this short review based on scientific papers, including data from the last two decades, presents methods for obtaining nanoparticulate iron oxides as well as the main aspects of the different characterization techniques and also about the decomposition aspects of these nanomaterials. Morphologies and structures of iron oxides can be characterized through transmission electron microscopy, scanning electron microscopy, X-ray powder diffraction, and Fourier transform infrared spectroscopy. As for textural properties, they are usually determined by physical adsorption techniques.

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“…This process yields cubic or spherical particles with characteristic narrow pore size ranging from 4 to 15 nm and high surface area (~315 m 2 g -1 ) [30,31] . Water-in-oil microemulsion consisting of a cationic or non-ionic surfactant (Triton-X), a co-surfactant (glycols, hexanol, 1-butanol), oil phase (n-octane, cyclohexane) and the aqueous phase is generally used to prepare magnetic iron oxide nanoparticles with controlled size and morphology [32] . The microemulsion is formed through the addition of an aqueous solution with iron salt precursors.…”

Section: Iron Oxide Nmmentioning

confidence: 99%

Nanomaterials in Soil Environment: A Review

Bhattacharya

Das

2020

NJAS

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Nanomaterials (NMs) have become an integral part of our daily life and their extensive uproduction will only increase with the coming time. These NMs exhibit significant contrast in regard to dimension, reaction, and structure. The most important aspect of the NMs is that these can be easily manipulated and engineered to custom-suit different functions/industries. Owing totheir dynamic nature, these NMs behave differently when introduced in any medium. In soil, the behavior of NMs is significantly controlled by the interactions of nanomaterials with soil phases. Although, NMs are deemed beneficial for human-use yet these also carry lethal effects. Moreover, there is dearth of adequate research with respect to the interactions amongnanomaterials and soil physicochemical properties; their accumulation-dissolution dynamics in soil-plant systems; and their long term influence on soil health. Several NMs induce physiological stress when introduced inside the body. Thus, various researchers have devised green pathways for producing NMs, although their wide applicability is still questionable. Although the domain of nanotechnology is greatly explored yet there remain several grey areaswhich need to be addressed for sustainable utilization of these unique materials in the benefit of humankind.

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The competing effect of ammonia in the synthesis of iron oxide/silica nanoparticles in microemulsion/sol–gel system

Cited by 28 publications

References 17 publications

Chemical and Textural Characterization of Iron Oxide Nanoparticles and Their Effect on the Thermal Decomposition of Ammonium Perchlorate

Chemical and Textural Characterization of Iron Oxide Nanoparticles and Their Effect on the Thermal Decomposition of Ammonium Perchlorate

Synthesis, Characterization and Applications of Iron Oxide Nanoparticles - a Short Review

Nanomaterials in Soil Environment: A Review

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