Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 16 de 16
Filtrar
Filtros adicionais











Intervalo de ano
1.
J Nanosci Nanotechnol ; 20(2): 769-778, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-31383072

RESUMO

A super absorbent was synthesized from calcium-aluminum waste residue of aluminum industrial using a facile hydrothermal method. The XRD results revealed that the main phase of hydrothermal product at 120 °C is CaSO4 ·2H2O, with a small amount of Al(OH)3. The as-prepared products were used to investigate the adsorptive applications in Congo red (CR) removal, and the results showed that the products treated at 120 °C had the best adsorption properties. The maximum adsorption capacity reaches about 1860.11 mg/g with a removal rate of 99.75%. Furthermore, the used adsorbent could be regenerated for at least four cycles through a calcination procedure, indicating its potential as an excellent adsorbent for the removal of CR dye from wastewater. The adsorption behavior was analyzed by Langmuir, Freundlich and Sips isotherms, and the adsorption proved to be a multilayer adsorption. This facile method presented here may provide promise synthesis of high-effective and low-cost adsorbents from industrial solid waste and achieve the goal of "using waste to treat waste" in the future.

2.
Environ Pollut ; 254(Pt A): 112961, 2019 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-31398635

RESUMO

CoFe2O4/C nano-sheets (NSs) have been synthesized by a facile molten salt method using cheap potassium fulvate as carbon source and sodium chloride as template. The morphology, crystallinity and composition of the materials were analyzed by TEM, XRD and XPS. The study on the catalytic performance of 4-nitrophenol (4-NP) shows that CoFe2O4/C-600 nano-catalyst has the highest catalytic activity and the corresponding apparent constant is 1.91 min-1, this result is higher than that reported in most literatures. Catalytic kinetics of 4-NP reduction was studied in this article, and activation energy (Ea) was calculated to be 14.31 kJ mol-1. The catalyst also shows good cycle performance and stability. This convenient method provides a reference for the synthesis of MFe2O4/C and other nano-metal oxides/C nanocomposite catalysts.

3.
Sensors (Basel) ; 19(5)2019 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-30871099

RESUMO

In this paper, WO3·0.33H2O nanorods were prepared through a simple hydrothermal method using p-aminobenzoic acid (PABA) as an auxiliary reagent. X-ray diffraction (XRD) and transmission electron microscopy (TEM) images showed that the products with PABA addition were orthorhombic WO3·0.33H2O, which were mainly composed of nanorods with different crystal planes. The sensing performance of WO3·0.33H2O nanorod bundles prepared by the addition of PABA (100 ppm cyclohexene, Ra/Rg = 50.6) was found to be better than the WO3 synthesized without PABA (100 ppm cyclohexene, Ra/Rg = 1.3) for the detection of cyclohexene. The new synthesis route and sensing characteristics of as-synthesized WO3·0.33H2O nanorods revealed a promising candidate for the preparation of the cost-effective gas sensors.

4.
J Hazard Mater ; 371: 213-223, 2019 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-30852273

RESUMO

Here, hierarchical nanostructures of clay-based hybrids were synthesized via a space-confined growth of layered basic zinc acetate (LBZA) nanosheets standing upright on both sides of bentonite clay platelets. These thermally instable LBZA nanosheets were thermally decomposed and fragmented into ZnO nanoparticles well-dispersed on bentonite platelets. The morphology and structure of LBZA/bentonite and ZnO/bentonite was characterized by SEM, TEM, XRD, TG-DSC, and FTIR. Surface density of LBZA nanosheets on bentonite platelets was simply controlled by tuning the amount of zinc acetate. LBZA/bentonite and ZnO/bentonite was used for the adsorption of Congo red (CR) and photodegradation of methyl orange (MO), respectively. Results showed that LBZA/bentonite exhibited higher adsorption capacity for Congo red (CR) than original bentonite. In addition, bentonite-supported ZnO nanoparticles efficiently promoted the photodegradation of MO under UV light irradiation.

5.
Adv Sci (Weinh) ; 5(8): 1800271, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30128240

RESUMO

The unique physicochemical properties of silver nanoparticles offer a large potential for biomedical application, however, the serious biotoxicity restricts their usage. Herein, nanogalvanic couple Ag-Fe@Fe3O4 heterostructures (AFHs) are designed to prevent Ag+ release from the cathodic Ag by sacrificial anodic Fe, which can reduce the cytotoxicity of Ag. AFHs are synthesized with modified galvanic displacement strategy in nonaqueous solution. To eliminate the restriction of lattice mismatch between Fe and Ag, amorphous Fe@Fe3O4 nanoparticles (NPs) are selected as seeds, meanwhile, reductive Fe can reduce Ag precursor directly even at as low as 20 °C without additional reductant. The thickness of the Fe3O4 shell can influence the amorphous properties of AFHs, and a series of Janus- and satellite-like AFHs are synthesized. A "cut-off thickness" effect is proposed based on the abnormal phenomenon that with the increase of reaction temperature, the diameter of Ag in AFHs decreases. Because of the interphase interaction and the coupling effect of Ag and Fe@Fe3O4, the AFHs exhibit unique optical and magnetic properties. This strategy for synthesis of monodisperse heterostructures can be extended for other metals, such as Au and Cu.

6.
Nanoscale Res Lett ; 13(1): 129, 2018 Apr 27.
Artigo em Inglês | MEDLINE | ID: mdl-29704073

RESUMO

A facile, cost-effective, non-toxic, and surfactant-free route has been developed to synthesize MoS2/carbon (MoS2/C) nanocomposites. Potassium humate consists of a wide variety of oxygen-containing functional groups, which is considered as promising candidates for functionalization of graphene. Using potassium humate as carbon source, two-dimensional MoS2/C nanosheets with irregular shape were synthesized via a stabilized co-precipitation/calcination process. Electrochemical performance of the samples as an anode of lithium ion battery was measured, demonstrating that the MoS2/C nanocomposite calcinated at 700 °C (MoS2/C-700) electrode showed outstanding performance with a high discharge capacity of 554.9 mAh g- 1 at a current density of 100 mA g- 1 and the Coulomb efficiency of the sample maintained a high level of approximately 100% after the first 3 cycles. Simultaneously, the MoS2/C-700 electrode exhibited good cycling stability and rate performance. The success in synthesizing MoS2/C nanocomposites via co-precipitation/calcination route may pave a new way to realize promising anode materials for high-performance lithium ion batteries.

7.
ACS Nano ; 11(9): 9239-9248, 2017 09 26.
Artigo em Inglês | MEDLINE | ID: mdl-28850218

RESUMO

Imaging-guided photothermal therapy (PTT) by combination of imaging and PTT has been emerging as a promising therapeutic method for precision therapy. However, the development of multicomponent nanoplatforms with stable structures for both PTT and multiple-model imaging remains a great challenge. Herein, we synthesized monodisperse Au-Fe2C Janus nanoparticles (JNPs) of 12 nm, which are multifunctional entities for cancer theranostics. Due to the broad absorption in the near-infrared range, Au-Fe2C JNPs showed a significant photothermal effect with a 30.2% calculated photothermal transduction efficiency under 808 nm laser irradiation in vitro. Owing to their excellent optical and magnetic properties, Au-Fe2C JNPs were demonstrated to be advantageous agents for triple-modal magnetic resonance imaging (MRI)/multispectral photoacoustic tomography (MSOT)/computed tomography (CT) both in vitro and in vivo. We found that Au-Fe2C JNPs conjugated with the affibody (Au-Fe2C-ZHER2:342) have more accumulation and deeper penetration in tumor sites than nontargeting JNPs (Au-Fe2C-PEG) in vivo. Meanwhile, our results verified that Au-Fe2C-ZHER2:342 JNPs can selectively target tumor cells with low cytotoxicity and ablate tumor tissues effectively in a mouse model. In summary, monodisperse Au-Fe2C JNPs, used as a multifunctional nanoplatform, allow the combination of multiple-model imaging techniques and high therapeutic efficacy and have great potential for precision theranostic nanomedicines.

8.
ACS Appl Mater Interfaces ; 9(21): 18207-18214, 2017 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-28497953

RESUMO

In this paper, hollow nanospheres (HNSs) of metal oxides (NiO, CuO, and NiO/CuO) coated with a porous carbon shell (HNSs@C) with good structural stability were successfully prepared on the basis of the nanoscale Kirkendall effect. The formation process was based on a template-free method, and the as-prepared HNSs@C are very clean compared with products of the template process. In addition, the results of N2 adsorption-desorption noted that both the metal oxide HNSs and the coated carbon were mesoporous structures. Therefore, small molecules can access the inner space of the whole HNSs@C, which was expected to increase the active site area and to show better performances in applied fields, such as catalysts and sensors. As an example of the functional properties, the obtained HNSs@C were investigated as the catalyst for the hydrogenation of 4-nitrophenol (4-NP) and manifested highly catalytic activity and excellent stability. This work has opened up a novel route for the development of metal oxide HNSs nanocatalysts. This straightforward method is of significance for development of clean metal oxide HNSs with high stability and multiplied applications.

9.
Chem Commun (Camb) ; 52(60): 9450-3, 2016 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-27377872

RESUMO

A novel surface sulfur (S) doped cobalt (Co) catalyst for the oxygen evolution reaction (OER) is theoretically designed through the optimisation of the electronic structure of highly reactive surface atoms which is also validated by electrocatalytic OER experiments.


Assuntos
Cobalto/química , Oxigênio/química , Enxofre/química , Catálise , Elétrons , Estrutura Molecular , Oxirredução , Propriedades de Superfície
10.
Small ; 12(21): 2866-71, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27087475

RESUMO

A strongly coupled CoCr2 O4 /carbon nanosheet composite is concurrently grown via a facile one-step molten-salt calcination approach. The strong coupling between carbon and CoCr2 O4 has improved the electrical conductivity and preserved the active sites in catalysts. These results may pave the way to improve the performance of spinel oxides as electrocatalysts for oxygen evolution reactions.

11.
Small ; 12(10): 1351-8, 2016 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-26756919

RESUMO

The development of earth-abundant, active, and stable catalysts is important for solar energy conversion. Metal-organic frameworks (MOFs) have been viewed as a promising class of porous materials, which may have innovative application in photocatalysis. In this paper, three types of Fe-based MOFs and their aminofunctionalized derivatives have been fabricated and systematically studied as water oxidation catalysts (WOCs) for oxygen evolution under visible light irradiation. MIL-101(Fe) possesses a higher current density and earlier onset potential and exhibits excellent visible light-driven oxygen evolution activity than the other Fe-based catalysts. It speeds up the oxygen evolution reaction rate with the higher initial turnover frequencies value of 0.10 s(-1). Our study demonstrates that Fe-based MOFs as efficient WOCs are promising candidates for photocatalytic water oxidation process.

12.
J Colloid Interface Sci ; 452: 116-125, 2015 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-25935282

RESUMO

A phase transfer method was developed to prepare boehmite (γ-AlOOH) nanostructures with various morphologies including nanofragments, nanorods, nanoflakes and multiply stacked nanostructures. The effect of the reaction temperature on the morphology of the as-prepared γ-AlOOH was investigated systematically. After calcination, the corresponding aluminum oxide (γ-Al2O3) nanostructures were obtained from the as-prepared γ-AlOOH products and preserving the same morphology. The obtained samples were characterized by several techniques, such as X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and N2 adsorption-desorption technique. The possible formation mechanism of the boehmites has also been proposed. Adsorption experiments indicated that γ-Al2O3 nanorods exhibited better adsorption capacity for Congo red (CR) in contrast to other as-prepared γ-Al2O3 nanostructures and commercial alumina (Al2O3), and the adsorption obeyed well to Langmuir isotherm model. Besides, the adsorption kinetics followed pseudo-second-order rate equation.

13.
J Colloid Interface Sci ; 435: 34-42, 2014 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-25217728

RESUMO

CuO nanoparticles with different morphologies were synthesized by chemical precipitation and subsequently modified by microwave hydrothermal processing. The nanoparticles were precipitated by the introduction of a strong base to an aqueous solution of copper cations in the presence/absence of the polyethylene glycol and urea additives. The modification of the nanoparticles was subsequently carried out by a microwave hydrothermal treatment of suspensions of the precipitates, precipitated with and without the additives. X-ray powder diffraction analysis indicated that the crystallinity and crystallite size of the CuO nanoparticles increased after the microwave hydrothermal modification. Microscopy observations revealed the morphology changes induced by microwave hydrothermal processing. The thermal decomposition of ammonium perchlorate and the detection of volatile gases were performed to evaluate the catalytic and gas sensing properties of the synthesized CuO nanoparticles.

14.
J Colloid Interface Sci ; 407: 296-301, 2013 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-23856060

RESUMO

A general microwave-assisted two-phase strategy (MTS) has been developed for the synthesis of monodisperse inorganic nanocrystals (NCs). A series of metal oxides, ferrite, hydroxides, and metal sulfide NCs were synthesized by using water-soluble metal salts. The obtained NCs were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The composition, size, and shape of the NCs can be tuned by the types of precursors, the concentrations of metal ions, and the species of ligands. This protocol creates a new synthetic route, which may also be further extended to synthesize other nanomaterials, including alloy, noble metal, rare-earth fluorescent, etc.

15.
Chemistry ; 12(12): 3303-9, 2006 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-16470769

RESUMO

The frontal polymerization process was used to produce superabsorbent hydrogels based on acrylic acid monomers grafted onto starch. Using a simple test tube which was nonadiabatic and permitted contact with air, the effects of initial temperature and tube size on the propagating front of grafting copolymerization and the properties of hydrogels were explored. The unrestricted access of the reaction mixture to oxygen delayed the formation of self-propagating polymerization front. The ignition time was markedly lengthened with the increasing of tube size attributed to the formation of large amounts of peroxy radicals. The front velocity dependence on initial temperature could be fit to an Arrhenius function with the average apparent activation energy of 24 kJ mol(-1), and on tube size to a function of higher order. The increase of the initial temperature increased the front temperature, which lead to more soluble oligomers and higher degree of crosslinking. The interplay of two opposite effects of oligomer and crosslinking determined the sol and gel content. An increase in tube size had two effects on the propagating front. One was to reduce heat loss. The other effect was to increase the number of escaping gas bubbles. The combined action of the two effects resulted in a maximum value of front temperature, an increase in sol content and a reduction in gel content with tube size. The highest swelling capacity of hydrogels was obtained when the initial temperature or tube size favored a formation of porous microstructure of hydrogels.

16.
Chemistry ; 11(22): 6609-15, 2005 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-16130162

RESUMO

Recently, a considerable amount of research has centered on uniquely structured polymers synthesized through self-propagating frontal polymerization. The obtained polymer materials have better features than those obtained by using the classical batch route. The additional advantages are short reaction times and low cost. This work describes the first frontal polymerization synthesis of a graft copolymer superabsorbent hydrogel of acrylic acid onto starch at high monomer and initiator concentration. The effects of varying the relative amounts of the reaction components on the most relevant parameters relating to frontal polymerization were explored. The front velocity dependence on initiator concentration could be fit to a power function. The temperature profiles were found to be very sharp with a maximum temperature below 150 degrees C, which was responsible for high monomer conversion. The ultimate properties of the product appear to depend on the polymerization front velocity and the temperature. The high-temperature and rapid temperature increase at the polymerization front led to products with interconnected porous structures caused by the evaporation of water. So, a fast-swelling, highly absorbing hydrogel with respect to batch polymerization was obtained.


Assuntos
Aceleração , Resinas Acrílicas/química , Hidrogéis/síntese química , Amido/química , Absorção , Tamanho da Partícula , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Temperatura Ambiente , Água/química
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA