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1.
Sci Rep ; 12(1): 21294, 2022 Dec 09.
Artigo em Inglês | MEDLINE | ID: mdl-36494421

RESUMO

Novel alumina-based materials enriched with vanadia and lanthana were successfully synthesized via in situ modification using a mechanochemical method, and were applied in ammonia-induced selective catalytic reduction of nitrogen oxides (SCR process). The synthesis was optimized in terms of the ball milling time (3 or 5 h), vanadium content (0.5, 1 or 2 wt% in the final product), and lanthanum content (0.5 or 1 wt% in the final product). Vanadium (V) oxide was immobilized on an alumina support to provide catalytic activity, while lanthana was introduced to increase the affinity of nitrogen oxides and create more active adsorption sites. Mechanochemical synthesis successfully produced mesoporous materials with a large specific surface area of 279-337 m2/g and a wide electrokinetic potential range from 60 to (- 40) mV. Catalytic tests showed that the incorporation of vanadia resulted in a very large improvement in catalytic performance compared with pristine alumina, increasing its efficiency from 14 to 63% at 400 °C. The best SCR performance, a 75% nitrogen oxide conversion rate at a temperature of 450 °C, was obtained for alumina enriched with 2 and 0.5 wt% of vanadium and lanthanum, respectively, which may be considered as a promising result.


Assuntos
Óxido de Alumínio , Amônia , Óxido de Alumínio/química , Amônia/química , Catálise , Óxidos de Nitrogênio/química , Óxidos/química , Oxirredução
2.
Biomater Sci ; 9(23): 7996-8006, 2021 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-34714299

RESUMO

Although a biologically nonessential element in living organisms, aluminum is notably nontoxic to eukaryotic cells and has a venerable history of medicinal use. We demonstrate that polyethylene glycol-coated γ-alumina nanoparticles (Al2O3-NPs) with an average size of 15 nm prepared from a commercial bulk γ-alumina (γ-Al2O3) via the top-down sonication technique exhibit antibacterial activity that is comparable to that of AgNPs against both the Gram-negative drug-susceptible Pseudomonas aeruginosa (DSPA) and multidrug-resistant Pseudomonas aeruginosa (DRPA) bacteria, while the antibacterial activity of such Al2O3-NPs considerably surpasses that of AgNPs against both the Gram-positive methicillin-susceptible Staphylococcus aureus (DSSA) and methicillin-resistant Staphylococcus aureus (MRSA) bacteria. We also demonstrate that the DSPA bacteria sequentially exposed to Al2O3-NPs for 30 days show no indication of resistance development. Furthermore, such Al2O3-NPs can completely overcome the drug resistance developed in the conventional antibiotic ciprofloxacin-resistant and AgNP-resistant mutants without developing Al resistance.


Assuntos
Anti-Infecciosos , Nanopartículas Metálicas , Staphylococcus aureus Resistente à Meticilina , Alumínio , Óxido de Alumínio , Antibacterianos/farmacologia , Testes de Sensibilidade Microbiana , Pseudomonas aeruginosa , Prata/farmacologia
3.
J Colloid Interface Sci ; 501: 248-255, 2017 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-28458225

RESUMO

Mesoporous δ-Bi2O3 samples with high surface area and small crystallite sizes were prepared by using different SBA-15 silicas as hard templates. The latter were synthesized hydrothermally using tetraethylorthosilicate (TEOS), sodium metasilicate (SMS), and water glass (WG) as silica sources. The resulting SBA-15 silicas showed high surface area and pore volume. Among SBA-15 samples studied, the WG-generated SBA-15 exhibited the thinnest pore walls and lowest percentage of complementary pores. Interestingly, SBA-15 obtained from WG gave δ-Bi2O3 with the highest surface area and pore volume. This mesoporous δ-Bi2O3 was applied for the removal of iodide from aqueous solutions and was able to adsorb 2.87mmol/g of iodide at ambient conditions. In addition, mesoporous δ-Bi2O3 displayed high selectivity for iodide removal in the presence of chloride. Due to the high toxicity of the radioactive isotopes of iodine, this substance is required to be immobilized before its release to environment. This work presents a promising sorbent for selective capture of iodide from aqueous solutions.

4.
Small ; 13(6)2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27860353

RESUMO

Design and synthesis of porous and hollow carbon spheres have attracted considerable interest in the past decade due to their superior physicochemical properties and widespread applications. However, it is still a big challenge to achieve controllable synthesis of hollow carbon nanospheres with center-radial large mesopores in the shells and inner surface roughness. Herein, porous hollow carbon nanospheres (PHCNs) are successfully synthesized with tunable center-radial mesopore channels in the shells and crater-like inner surfaces by employing dendrimer-like mesoporous silica nanospheres (DMSNs) as hard templates. Compared with conventional mesoporous nanospheres, DMSN templates not only result in the formation of center-radial large mesopores in the shells, but also produce a crater-like inner surface. PHCNs can be tuned from open center-radial mesoporous shells to relatively closed microporous shells. After functionalization with polyethyleneimine (PEI) and poly(ethylene glycol) (PEG), PHCNs not only have negligible cytotoxicity, excellent photothermal property, and high coloading capacity of 482 µg of doxorubicin and 44 µg of siRNA per mg, but can also efficiently deliver these substances into cells, thus displaying enhanced cancer cell killing capacity by triple-combination therapy.


Assuntos
Carbono/química , Doxorrubicina/farmacologia , Hipertermia Induzida , Nanosferas/química , Fototerapia , RNA Interferente Pequeno/metabolismo , Células A549 , Materiais Biocompatíveis/farmacologia , Humanos , Nanosferas/ultraestrutura , Porosidade , Eletricidade Estática
5.
ACS Appl Mater Interfaces ; 4(4): 2174-9, 2012 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22458371

RESUMO

Porous micro- and nanostructured materials with desired morphologies and tunable pore sizes are of great interests because of their potential applications in environmental remediation. In this study, novel rattle-type carbon-alumina core-shell spheres were prepared by using glucose and metal salt as precursors via a simple one-pot hydrothermal synthesis followed by calcination. The microstructure, morphology, and chemical composition of the resulting materials were characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N(2) adsorption-desorption techniques. These rattle-type spheres are composed of a porous Al(2)O(3) shell (thickness ≈ 80 nm) and a solid carbon core (diameter ≈ 200 nm) with variable space between the core and shell. Furthermore, adsorption experiments indicate that the resulting carbon-alumina particles are powerful adsorbents for the removal of Orange-II dye from water with maximum adsorption capacity of ~210 mg/g. It is envisioned that these rattle-type composite particles with high surface area and large cavities are of particular interest for adsorption of pollutants, separation, and water purification.


Assuntos
Óxido de Alumínio/química , Carbono/química , Corantes/química , Poluentes Químicos da Água/química , Purificação da Água/instrumentação , Adsorção , Tamanho da Partícula , Porosidade , Purificação da Água/métodos
6.
J Colloid Interface Sci ; 367(1): 129-34, 2012 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-22041196

RESUMO

Ordered mesoporous aluminas with high surface areas (up to 783 m(2)/g), large pore volumes (up to 0.82 cm(3)/g) and the presence of complementary micropores (up to 0.17 cm(3)/g) are synthesized with Pluronic® F127 or P123 triblock copolymers in a one-pot synthesis of metal alkoxide, template and cosolvent molecules such as 1,3,5-trimethylbenzene or 1,3,5-triisopropylbenzene in an acidic ethanol solution at 15 °C. Materials are characterized by nitrogen adsorption analysis, small-angle X-ray diffraction and transmission electron microscopy.


Assuntos
Óxido de Alumínio/síntese química , Poloxâmero/química , Adsorção , Óxido de Alumínio/química , Microscopia Eletrônica de Transmissão , Poloxâmero/síntese química , Porosidade , Propriedades de Superfície , Difração de Raios X
7.
ACS Appl Mater Interfaces ; 3(11): 4480-6, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21988174

RESUMO

Incorporation of organic functionalities into soft-templated mesoporous alumina was performed via organosilane-assisted evaporation induced self-assembly using aluminum alkoxide precursors and block copolymer templates. This strategy permits one to obtain mesoporous alumina-based materials with tailorable adsorption, surface and structural properties. Isocyanurate, ethane, mercaptopropyl, and ureidopropyl-functionalized mesoporous alumina materials were synthesized with relatively high surface area and large pore volume with uniform and wormhole-like mesopores. The presence of organosilyl groups within these hybrid materials was confirmed by IR or Raman spectroscopy and their concentration was determined by elemental analysis.


Assuntos
Óxido de Alumínio/química , Adsorção , Estrutura Molecular , Porosidade , Propriedades de Superfície
8.
Nanoscale ; 2(12): 2868-72, 2010 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-20835448

RESUMO

Novel α-alumina crystalline nanosheets are used for the preparation of alumina-carbon composites, in which the latter component is phenolic resin-based ordered mesoporous carbon. A unique feature of these composites is perpendicular orientation of ordered mesopores of the carbon to the (001) facets of nonporous α-alumina nanosheets accompanied by significant enlargement of these mesopores in comparison to those present in the bulk carbon.


Assuntos
Óxido de Alumínio/química , Carbono/química , Nanocompostos/química , Cristalização , Nanocompostos/ultraestrutura , Porosidade , Difração de Raios X
9.
J Am Chem Soc ; 130(45): 15210-6, 2008 Nov 12.
Artigo em Inglês | MEDLINE | ID: mdl-18921999

RESUMO

The one-pot synthesis of alumina-supported metal oxides via self-assembly of a metal precursor and aluminum isopropoxide in the presence of triblock copolymer (as a structure directing agent) is described in detail for nickel oxide. The resulting mesoporous mixed metal oxides possess p6 mm hexagonal symmetry, well-developed mesoporosity, relatively high BET surface area, large pore widths, and crystalline pore walls. In comparison to pure alumina, nickel aluminum oxide samples exhibited larger mesopores and improved thermal stability. Also, long-range ordering of the aforementioned samples was observed for nickel molar percentages as high as 20%. The generality of the recipe used for the synthesis of mesoporous nickel aluminum oxide was demonstrated by preparation of other alumina-supported metal oxides such as MgO, CaO, TiO 2, and Cr 2O 3. This method represents an important step toward the facile and reproducible synthesis of ordered mesoporous alumina-supported materials for various applications where large and accessible pores with high loading of catalytically active metal oxides are needed.


Assuntos
Óxido de Alumínio/química , Níquel/química , Adsorção , Espectroscopia de Ressonância Magnética/métodos , Modelos Moleculares , Nitrogênio/química , Termogravimetria , Difração de Raios X
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