New product from old reaction: uniform magnetite nanoparticles from iron-mediated synthesis of alkali iodides and their protection from leaching in acidic media

RSC Advances ◽  
2014 ◽  
Vol 4 (43) ◽  
pp. 22606-22612 ◽  
Author(s):  
R. P. Pogorilyi ◽  
I. V. Melnyk ◽  
Y. L. Zub ◽  
S. Carlson ◽  
G. Daniel ◽  
...  
Keyword(s):  
Magnetic Material ◽  
Magnetite Nanoparticles ◽  
Acid Leaching ◽  
New Product ◽  
Silica Coating ◽  
Acidic Media ◽  
Industrial Synthesis

Magnetic material stable to acid leaching was produced by silica coating of byproduct from the industrial synthesis of alkali iodides.

scholarly journals Magnetite–Corrole Hybrid Nanoparticles

2018 ◽  
Vol 4 (3) ◽  
pp. 37
Author(s):  
Rute Pereira ◽  
Tito Trindade ◽  
Joana Barata
Keyword(s):  
Magnetite Nanoparticles ◽  
Silica Coating ◽  
Hybrid Nanoparticles ◽  
Hydrothermal Route ◽  
Shell Nanoparticles ◽  
Lower Efficiency ◽  
Oxygen Generation ◽  
Transmission Electron ◽  
Pyridine Complex ◽  
Core Shell Nanoparticles

This study describes the first example of a hybrid material comprising corrole- and silica-coated magnetite nanoparticles. Firstly, cuboid and spheroid magnetite nanoparticles were prepared using a simple hydrothermal route, followed by a silica coating. The hybrid nanoparticles were obtained by promoting a covalent link between a gallium (III)(pyridine) complex of 5,10,15-tris(pentafluorophenyl)corrole (GaPFC) and the surface of magnetite–silica core/shell nanoparticles (Fe3O4@SiO2), shaped both as cuboids and spheroids. The hybrids were characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), ultraviolet-visible spectrophotometry (UV-Vis) and transmission electron microscopy (TEM). Preliminary studies on the capacity of singlet oxygen generation of the hybrid nanoparticles showed that these have lower efficiency values when compared to the pure corrole compound.

scholarly journals Improving Longitudinal Transversal Relaxation Of Gadolinium Chelate Using Silica Coating Magnetite Nanoparticles

2019 ◽  
Vol Volume 14 ◽  
pp. 7879-7889
Author(s):  
Kai Xu ◽  
Heng Liu ◽  
Junfeng Zhang ◽  
Haipeng Tong ◽  
Zhenghuan Zhao ◽  
...  
Keyword(s):  
Magnetite Nanoparticles ◽  
Silica Coating ◽  
Gadolinium Chelate

Effects of silica coating on the magnetic properties of magnetite nanoparticles

2019 ◽  
Vol 14 ◽  
pp. 34-43 ◽  
Author(s):  
Estelle Silva Diorato Teixeira de Mendonça ◽  
Anna Carolina Britto de Faria ◽  
Sílvia Cláudia Loureiro Dias ◽  
Fermin F.H. Aragón ◽  
John C. Mantilla ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Magnetite Nanoparticles ◽  
Silica Coating

scholarly journals An Ab Initio Investigation of the 4,4′-Methlylene Diphenyl Diamine (4,4′-MDA) Formation from the Reaction of Aniline with Formaldehyde

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 398 ◽  
Author(s):  
R. Boros ◽  
László Farkas ◽  
Károly Nehéz ◽  
Béla Viskolcz ◽  
Milán Szőri
Keyword(s):  
Transition State ◽  
Gas Phase ◽  
Acid Strength ◽  
Standard Enthalpy Of Formation ◽  
Side Reactions ◽  
Acidic Media ◽  
Pka Calculation ◽  
Industrial Synthesis ◽  
Dead End ◽  
Competing Reactions

The most commonly applied industrial synthesis of 4,4′-methylene diphenyl diamine (4,4′-MDA), an important polyurethane intermediate, is the reaction of aniline and formaldehyde. Molecular understanding of the 4,4′-MDA formation can provide strategy to prevent from side reactions. In this work, a molecular mechanism consisted of eight consecutive, elementary reaction steps from anilines and formaldehyde to the formation of 4,4′-MDA in acidic media is proposed using accurate G3MP2B3 composite quantum chemical method. Then G3MP2B3-SMD results in aqueous and aniline solutions were compared to the gas phase mechanism. Based on the gas phase calculations standard enthalpy of formation, entropy and heat capacity values were evaluated using G3MP2B3 results for intermediates The proposed mechanism was critically evaluated and important side reactions are considered: the competition of formation of protonated p-aminobenzylaniline (PABAH+), protonated aminal (AMH+) and o-aminobenzylaniline (OABAH+). Competing reactions of the 4,4′-MDA formation is also thermodynamically analyzed such as the formation of 2,4-MDAH+, 3,4-MDAH+. AMH+ can be formed through loose transition state, but it becomes kinetic dead-end, while formation of significant amount of 2,4-MDA is plausible through low-lying transition state. The acid strength of the key intermediates such as N-methylenebenzeneanilium, PABAH+, 4-methylidenecyclohexa-2,5-diene-1-iminium, and AMH+ was estimated by relative pKa calculation.

scholarly journals Synthesis and characterization of magnetic nanoparticles coated with silica through a sol-gel approach

Cerâmica ◽  
2009 ◽  
Vol 55 (336) ◽  
pp. 420-424 ◽  
Author(s):  
A. L. Andrade ◽  
D. M. Souza ◽  
M. C. Pereira ◽  
J. D. Fabris ◽  
R. Z. Domingues
Keyword(s):  
Fourier Transform ◽  
Magnetic Nanoparticles ◽  
Magnetite Nanoparticles ◽  
Sol Gel ◽  
Reaction Medium ◽  
Fourier Transform Infrared ◽  
Silica Coating ◽  
Precipitation Method ◽  
Pure Silica

This paper investigates the influence of reaction medium pH on silica-coating of magnetite nanoparticles. Magnetite nanoparticles were prepared by means of a reduction-precipitation method using ferric chloride as a starting material, which was partially reduced to ferrous salts by Na2SO3 before alkalinizing with ammonia. The particles were coated by sol-gel method with either ammonia or HCl aqueous solutions for either base- or acid-catalyzed hydrolysis, respectively. Powder X-ray diffraction, Fourier-transform infrared, and Zeta Potential were used for the characterization of oxides and of the coated magnetic nanoparticles. The observed difference of pH IEP in KCl solution for pure silica (2.0), magnetite (5.0), and silica-coated magnetite (2.3) samples confirms that the coating process was effective since the charge surface properties of coated magnetic nanoparticles are close to that of pure silica, even though the Fourier-transform infrared spectra did not evidence the formation of Fe-O-Si bonds.

Synthesis of Small-Sized, Porous, and Low-Toxic Magnetite Nanoparticles by Thin POSS Silica Coating

2015 ◽  
Vol 21 (10) ◽  
pp. 3914-3918 ◽  
Author(s):  
Swee Kuan Yen ◽  
D. Prathyusha Varma ◽  
Wei Mei Guo ◽  
Vincent H. B. Ho ◽  
Vimalan Vijayaragavan ◽  
...  
Keyword(s):  
Magnetite Nanoparticles ◽  
Silica Coating ◽  
Low Toxic

scholarly journals Aggregation state and magnetic properties of magnetite nanoparticles controlled by an optimized silica coating

2017 ◽  
Vol 121 (4) ◽  
pp. 044304 ◽  
Author(s):  
Nicolás Pérez ◽  
C. Moya ◽  
P. Tartaj ◽  
A. Labarta ◽  
X. Batlle
Keyword(s):  
Magnetic Properties ◽  
Magnetite Nanoparticles ◽  
Silica Coating ◽  
Aggregation State
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