Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 82
Filtrar
Mais filtros

Base de dados
Tipo de documento
Intervalo de ano de publicação
1.
J Fluoresc ; 34(1): 397-409, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37278962

RESUMO

In the present system, Sm3+ activated Ba2BiV3O11 nanomaterial series radiating orange-red light was developed via an efficient approach of solution combustion method. The structural examinations using XRD analysis indicate that the sample is crystallized into the monoclinic phase with the P21/a (14) space group. The elemental composition and morphological conduct were studied via energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM) respectively. Also, the formation of nanoparticles was confirmed by transmission electron microscopy (TEM). Photoluminescent (PL) examinations reveal the orange-red emission from the developed nanocrystals via documenting the emission spectra, which reveals the peak at 606 nm due to the 4G5/2 → 6H7/2 transition. Further, the decay time, non-radiative rates, quantum efficiency, and band gap of the optimal sample were computed as 1.3263 ms, 219.5 s- 1, 70.88%, and 3.41 eV respectively. Finally, the chromatic parameters including color - coordinates (0.5565, 0.4426), 1975 K color correlated temperature (CCT), and color purity (85.58%) reflected their excellent luminous performance. The above-mentioned outcomes endorsed the relevancy of the developed nanomaterials as a propitious agent in the engineering of advanced illuminating optoelectronic appliances.

2.
J Fluoresc ; 2024 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-39153166

RESUMO

Solution combustion procedure was used to create a succession of Na3LaxSm1 - x(PO4)2 (x = 0.01-0.15 mol) nanocrystals that generate a warm deep reddish light. Both HR-TEM and X-ray diffraction examinations were used to examine the morphology and crystalline phase analysis. Energy-dispersive X-ray analysis (EDAX) approves the elemental examination. The luminescence spectrum exhibits a decent reddish-orange emission at 700 nm wavelength upon near-UV illumination, which aligns with the electronic transition 4G5/2 → 6H11/2. According to Dexter's idea, nearest neighbor interlinkages are responsible for the concentration quenching that occurs after the Sm3+ ion composition reaches 6 mol%. Additionally, a detailed evaluation of the radiative lifespan (0.7519 ms), quantum efficiency (77%), Non radiative rate (307.40), color temperature (3170 K), color purity (99.2%) and color coordinates (0.652, 0.338) was conducted. The optical characteristics that have been observed indicate that Sm3+ doped Na3La(PO4)2 phosphors could be a good option for improving WLED efficiency and color quality.

3.
Small ; 19(30): e2302238, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-37191328

RESUMO

Developing efficient and durable electrocatalysts for the oxygen evolution reaction (OER) in proton exchange membrane (PEM) electrolyzers represents a significant challenge. Herein, the cobalt-ruthenium oxide nano-heterostructures are successfully synthesized on carbon cloth (CoOx /RuOx -CC) for acidic OER through a simple and fast solution combustion strategy. The rapid oxidation process endows CoOx /RuOx -CC with abundant interfacial sites and defect structures, which enhances the number of active sites and the charge transfer at the electrolyte-catalyst interface, promoting the OER kinetics. Moreover, the electron supply effect of the CoOx support allows electrons to transfer from Co to Ru sites during the OER process, which is beneficial to alleviate the ion leaching and over-oxidation of Ru sites, improving the catalyst activity and stability. As a self-supported electrocatalyst, CoOx /RuOx -CC displays an ultralow overpotential of 180 mV at 10 mA cm-2 for OER. Notably, the PEM electrolyzer using CoOx /RuOx -CC as the anode can be operated at 100 mA cm-2 stably for 100 h. Mechanistic analysis shows that the strong catalyst-support interaction is beneficial to redistribute the electronic structure of RuO bond to weaken its covalency, thereby optimizing the binding energy of OER intermediates and lowering the reaction energy barrier.

4.
J Fluoresc ; 2023 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-37523137

RESUMO

Ca9Y(VO4)7 phosphor activated with Er3+ ions have been developed by the urea-aided solution combustion technique. XRD profiles assisted with Rietveld refinement executed over-developed Er3+-activated Ca9Y(VO4)7 powder, revealed a trigonal phase with the R3c space group. The electron microscope techniques namely TEM and SEM characterize the size and surface-linked qualities of the developed nanopowder, respectively. The uniform distribution of various elements in the nanocrystalline sample is authenticated by an energy-dispersive spectroscopy (EDS) system. The Eg (band gap) value of 3.64 eV for Ca9Y0.9Er0.1(VO4)7 and 3.74 eV for Ca9Y(VO4)7 has been estimated. Upon 382 nm excitation, Er3+: Ca9Y(VO4)7 phosphor gives rise to the bright green emission owing to the 4S3/2 → 4I15/2 transition. The concentration quenching after 10 mol% composition of trivalent erbium ions is attributed to dipole-dipole interlinkages in accordance with Dexter's theory. The radiative lifetime (1.1083 ms), non-radiative rates (0.2079 ms- 1), quantum efficiency (79%), along with colorimetric parameters i.e. CIE x (= 0.2577), y (= 0.4566), and CCT quantities offer Ca9Y0.9Er0.1(VO4)7 as a proficient green radiating nanomaterial for RGB phosphors in solid-state applications.

5.
Luminescence ; 38(2): 196-207, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36639986

RESUMO

Solution combustion synthesized ZnO nanoparticles that were Ce doped, Dy doped or co-doped at varying dopant concentrations were characterized for their microstructural, optical, and photoluminescence (PL) characteristics. The synthesized nanoparticles matched the standard hexagonal wurtzite structure of ZnO. The lattice fringes in the high-resolution transmission electron micrographs and the bright spotty rings in the selected area electron diffraction patterns authenticated the high crystallinity of the nanoparticles. The diffuse reflectance spectroscopy resolved the energy bandgap for the undoped ZnO as 3.18 eV, which decreased upon doping and co-doping. A sharp narrow ultraviolet emission peak at ~398 nm that originated from excitonic recombination was found in the PL spectra of the nanoparticles. The visible emission peaks in the PL spectra were assigned to the f-d and f-f electron transitions of Ce3+ and Dy3+ ions, respectively, in addition to different native defects in ZnO. The visible emissions (blue, yellow, and red) improved upon (Ce, Dy) co-doping, therefore (Ce, Dy) co-doped ZnO nanoparticles can be considered a promising luminescent material for the development of energy-saving light sources.


Assuntos
Nanopartículas , Óxido de Zinco , Óxido de Zinco/química , Luminescência , Nanopartículas/química
6.
Luminescence ; 38(7): 1149-1166, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35393749

RESUMO

A low temperature-assisted and oxalyl dihydrazide fuel-induced combustion synthesized series of uncalcined MgAl2 O4 :Eu3+ nanophosphors showed an average crystallite size of ~20 nm, and bandgap energy (Eg ) of 4.50-5.15 eV, and were validated using density functional theory and found to match closely with the experimental values. The photoluminescence characteristic emission peaks of Eu3+ ions were recorded between 480 and 680 nm. The nanophosphors excited at 392 nm showed f-f transitions assigned as 5 D0 →7 FJ (J = 0, 1, 2, and 3). The optimized MgAl2 O4 phosphors had Commission Internationale de l'Eclairage coordinates in the red region, a correlated colour temperature of 2060 K, and a colour purity of 98.83%. The estimated luminescence quantum efficiency ( η ) was observed to be ~63% using Judd-Ofelt analysis. Electrochemical and photocatalytic performance were explored and indicated its multifunctional applications. Therefore, MgAl2 O4 :Eu3+ nanophosphors could be used for the fabrication of light-emitting diodes, industrial dye degradation, and as electrodes for supercapacitor applications.


Assuntos
Temperatura Baixa , Európio , Európio/química , Temperatura , Luminescência
7.
Luminescence ; 2023 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-37986624

RESUMO

This paper presents a research investigation into the synthesis of vanadate oxides M3 (VO4 )2 (M: Mg or Zn) using the solution combustion method and investigates their structural, photoluminescence, and photocatalytic properties after introducing cerium (Ce) as a dopant. The resulting synthesized samples all display an orthorhombic crystalline structure with crystallite sizes ranging from 71 to 110 nm. Morphological diversity among the samples is revealed through field-emission scanning electron microscopy (FESEM) imagery. Diffuse reflectance spectroscopy discloses that the introduction of Ce3+ as a dopant leads to an increase in the band gap energy. Notably, when excited at a wavelength of 340 nm, the photoluminescence emission intensity reaches its peak across all samples. This intensity undergoes enhancement due to Ce3+ doping, causing a slight shift toward shorter wavelengths attributable to the augmented band gap resulting from the dopant. Markedly, among the investigated materials, Ce3+ -activated Mg3 (VO4 )2 stands out with the most pronounced emission intensity, positioning it as a highly promising luminescent material. Additionally, the incorporation of Ce3+ has a positive effect on the photocatalytic performance of Mg3 (VO4 )2 , resulting in notable improvement.

8.
Nanotechnology ; 33(41)2022 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-34763322

RESUMO

The active practical application of materials based on cubic zirconium dioxide (c-ZrO2) for catalysis, luminescence, and sorption of heavy metals demands the development of methods for its preparation in a nanostructured form. In this work, nanoparticles of undoped cubic zirconia were obtained by solution combustion method, the features of their structure and morphology were investigated, and the efficiency of their use as a basis for sorbents for the removal of hexavalent chromium Cr(VI) from aqueous solutions was evaluated. Based on XPS, it was established that the stabilization of the high-temperature cubic phase of c-ZrO2occurred due to oxygen vacancies which were formed during the synthesis by glycine-nitrate combustion. From the results of PXRD and Raman spectroscopy cubic structure of the obtained zirconium dioxide nanoparticles is concluded, the average crystallite size was approximately 2 nm. Adsorption structural analysis and SEM indicated aggregation of c-ZrO2nanocrystals into primary (45-95 nm) and secondary (submicron) agglomerates. The specific surface of the nanopowder determined by the Brunauer-Emmet-Teller method was 25.4 m2g-1, the pore volume was 0.1670 cm3g-1, the major part of which is associated with interparticle porosity. Using kinetic pH-metry, it was found that on the surface of synthesized c-ZrO2, rapidly hydrated aprotic Lewis acid centers predominated, and the point of zero charge was 5.8. The results of the sorption of Cr(VI) from aqueous solutions with a concentration of 48-242 mg l-1at 25 °C and pH = 5 are described by the Freundlich isotherm (R2 = 0.971), which corresponds to multilayer adsorption. The maximum adsorption capacity according to Langmuir was 33 mg g-1or 1.34 mg m-2per unit area. These results allow us to consider the obtained undoped zirconium dioxide as a promising base for sorbents of heavy metals.

9.
Nanotechnology ; 33(41)2022 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-35793617

RESUMO

The noble metal nanoparticles have attracted attention due to their excellent catalytic performance for CO oxidation at low temperatures. M-CeO2(M = Pd, Ag, Au) catalysts with different atomic ratios of M/Ce were deposited via solution combustion method. Among them, 3 at% Pd-CeO2, 5 at% Ag-CeO2and 1 at% Au-CeO2catalysts have better catalytic performances. Especially, 5 at% Ag-CeO2catalyst shows better low-temperature CO oxidation performance. The catalytic activity for CO oxidation follows the follows the following sequence: 5 at% Ag-CeO2(T50 = 69 °C) > 3 at% Pd-CeO2(T50 = 99 °C) >1 at% Au-CeO2(T50 = 115 °C). Meanwhile, the catalysts are characterized by means of powder x-ray diffraction, scanning electron microscope, transmission electron microscopy, Raman spectroscopy, x-ray photoelectron spectroscopy, Brunauer-Emmett-Teller and H2-TPR. The characterization results show that the 5 at% Ag-CeO2catalyst has excellent catalytic activity due to the good dispersion of Ag nanoparticles, the specific surface area of the material, and the reduction catalyst between different valence ions. Moreover, the surface of the catalyst enhances the mutual synergy, effectively promotes the generation of oxygen vacancies, and increases the active oxygen content of the catalyst surface. Finally, the catalytic mechanism of M-CeO2catalysts is summarized.

10.
Luminescence ; 37(1): 141-152, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34738699

RESUMO

In the current investigation, a series of NaCa1-x PO4 :xDy3+ (x = 0.1, 0.3, 0.5, 0.7, 1.0, 1.5 and 2 mol%) phosphors were synthesized using a solution combustion method and citric acid as fuel. The investigated results from the X-ray diffraction (XRD) pattern showed phase purity of the synthesized material and orthorhombic crystal structure with space group Pna21. Photoluminescence properties of the synthesized phosphors were investigated. The synthesized Dy3+ -activated phosphor displayed blue (482 nm) and yellow (576 nm) emission under near-ultraviolet or blue excitations. These emission bands were ascribed due to the 4 F9/2 →6 H15/2 and 4 F9/2 →6 H13/2 transitions of Dy3+ ions. Commission International de l'Eclairage chromaticity coordinates showed emission in the near-white region for the proposed phosphors under different excitations. In addition, the current-voltage (I-V) characteristics of the NaCa1-x PO4 :xDy3+ (x = 1.5 mol%) phosphor-coated silicon solar cell and an uncoated solar cell were investigated under a solar simulator. The I-V characteristics of the proposed phosphor-coated silicon solar cell showed enhancement in solar cell efficiency by ~7.92%. The entire studies and their outcomes showed that synthesized phosphors have potential as white light emitting diodes and for solar applications.


Assuntos
Disprósio , Luminescência , Difração de Raios X
11.
Molecules ; 27(3)2022 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-35164057

RESUMO

The impact of process conditions on the synthesis of NiMoO4 nanostructures using a solution combustion synthesis (SCS) method, in which agar powder and Ni(NO3)2 were utilized as fuel and as the oxidant, respectively, was thoroughly studied. The results show that the calcination temperature had a significant implication on the specific surface area, phase composition, particle size, band gap, and crystallite size. The influence of calcination time on the resulting physicochemical/structural/morphological properties of NiMoO4 nanostructures was found to be a major effect during the first 20 min, beyond which these properties varied to a lesser extent. The increase in the Ni/Mo atomic ratio in the oxide impacted the combustion dynamics of the system, which led to the formation of higher surface area materials, with the prevalence of the ß-phase in Ni-rich samples. Likewise, the change in the pH of the precursor solution showed that the combustion reaction is more intense in the high-pH region, entailing major implications on the physicochemical properties and phase composition of the samples. The change in the fuel content showed that the presence of agar is important, as it endows the sample with a fluffy, porous texture and is also vital for the preponderance of the ß-phase.

12.
Molecules ; 27(4)2022 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-35208991

RESUMO

Earth-abundant NiMo-oxide nanostructures were investigated as efficient electrocatalytic materials for the hydrogen evolution reaction (HER) in acidic media. Synthesis and non-synthesis parameters were thoroughly studied. For the non-synthesis parameters, the variation in Nafion loading resulted in a volcano-like trend, while the change in the electrocatalyst loading showed that the marginal benefit of high loadings attenuates due to mass-transfer limitations. The addition of carbon black to the electrocatalyst layer improved the HER performance at low loadings. Different carbon black grades showed a varying influence on the HER performance. Regarding the synthesis parameters, a calcination temperature of 500 °C, a calcination time between 20 and 720 min, a stoichiometric composition (Ni/Mo = 1), an acidic precursor solution, and a fuel-lean system were conditions that yielded the highest HER activity. The in-house NiMoO4/CB/Nafion electrocatalyst layer was found to offer a better long-term performance than the commercial Pt/C.

13.
Chemistry ; 26(42): 9099-9125, 2020 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-32134133

RESUMO

Solution combustion synthesis (SCS) has been widely used to produce simple and complex oxides with a desired morphology (size and shape). SCS is valuable due to low cost, simplicity and energy efficient synthesis. To guarantee the best molecular-level mixing of reactants in an aqueous or solvent-based solution some parameters need to be controlled, such as fuel type, metal cations precursors, stoichiometry ratio (φ), pH effect, atmosphere and initiation type. These determine the final properties of the oxide materials, providing the potential to reach different morphologies, which are essential for their final applications. This Review article focuses on the crucial parameters in SCS and how these affect the overall materials properties from nanostructures to thin films. To finalize, special attention is given to the application of SCS to form metal oxide thin films at low temperature and their application in thin film transistors (TFTs).

14.
J Environ Sci (China) ; 98: 196-204, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33097152

RESUMO

Various manganese oxides (MnOx) prepared via citric acid solution combustion synthesis were applied for catalytic oxidation of benzene. The results showed the ratios of citric acid/manganese nitrate in synthesizing process positively affected the physicochemical properties of MnOx, e.g., BET (Brunauer-Emmett-Teller) surface area, porous structure, reducibility and so on, which were in close relationship with their catalytic performance. Of all the catalysts, the sample prepared at a citric acid/manganese nitrate ratio of 2:1 (C2M1) displayed the best catalytic activity with T90 (the temperature when 90% of benzene was catalytically oxidized) of 212℃. Further investigation showed that C2M1 was Mn2O3 with abundant nano-pores, the largest surface area and the proper ratio of surface Mn4+/Mn3+, resulting in preferable low-temperature reducibility and abundant surface active adsorbed oxygen species. The analysis results of the in-situ Fourier transform infrared spectroscopy (in-situ FTIR) revealed that the benzene was successively oxidized to phenolate, o-benzoquinone, small molecules (such as maleates, acetates, and vinyl), and finally transformed to CO2 and H2O.


Assuntos
Benzeno , Manganês , Ácido Cítrico , Óxidos , Porosidade
15.
J Fluoresc ; 29(5): 1227-1239, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31606834

RESUMO

In the present study, combustion synthesis of zinc oxide and zinc sulfide nanoparticles as well as their composite was studied using zinc nitrate and thioacetamide as starting materials, and ethylene glycol as fuel. The influence of different parameters such as oxidizer to fuel (O:F) ratios and calcination process on the structure, microstructure, photoluminescence and optical properties was studied. X-ray diffraction (XRD) patterns showed different combinations of wurtzite structure for zinc oxide and zinc sulfide phases obtained using different O:F ratios of 1:1 and 2:3. Scanning electron microscopy (SEM) micrographs revealed that particles with different morphologies were synthesized depending on the O:F ratio. Besides, nanometer particles, or even quantum dots, could be obtained. Transmission electron microscopy (TEM) micrographs also showed the formation of zinc oxide/ zinc sulfide quantum dots composite using ethylene glycol fuel with O:F ratio of 2:3. Fourier transformed infrared (FTIR) analysis of samples showed carbon bonds of carbonaceous matters in addition to Zn-O and Zn-S bonds due to incomplete combustion. Photoluminescent emission spectra indicated that the highest intensity of emission in blue-green region was obtained from the particle synthesized using ethylene glycol and O:F ratio of 2:3, which may be related to the high density of lattice defects. Band gaps estimated using UV-visible (UV-Vis) spectra were 3.4 and 5.4 eV which can be assigned to the dual nature of particles: in some parts quantum size and in the other parts nanosize particles.

16.
Molecules ; 24(2)2019 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-30669524

RESUMO

Cr2O3 nanoparticles were prepared by solution combustion synthesis (SCS) with chromium nitrate as the precursor and glycine as the fuel. Commercial Cr2O3 and Cr2O3 prepared by a precipitation method were also included for comparison. The morphology, structure, acidity and particle size of fresh and spent Cr2O3 catalysts were investigated by techniques such as XRD, SEM, TEM, BET and NH3-TPD. In addition, catalytic performance was evaluated for the dehydrofluorination of 1,1,1,3,3-pentafluoropropane (CF3CH2CHF2, HFC-245fa) to 1,3,3,3-tetra-fluoropropene (CF3CH=CHF, HFO-1234ze). The catalytic reaction rate of Cr2O3 prepared by SCS method is as high as 6 mmol/h/g, which is about 1.5 times and 2 times higher than that of precipitated Cr2O3 and commercial Cr2O3, respectively. The selectivity to HFO-1234ze for all the catalysts maintains at about 80%. Compared with commercial and precipitated Cr2O3, Cr2O3-SCS prepared by SCS possesses higher specific surface area and acid amount. Furthermore, significant change in the crystal size of Cr2O3 prepared by SCS after reaction was not detected, indicating high resistance to sintering.


Assuntos
Compostos de Cromo/síntese química , Fluorocarbonos/química , Hidrocarbonetos Fluorados/química , Nanopartículas/química , Catálise , Halogenação , Concentração de Íons de Hidrogênio , Oxirredução , Tamanho da Partícula , Soluções , Propriedades de Superfície
17.
Int J Phytoremediation ; 19(12): 1126-1133, 2017 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-28521531

RESUMO

New carbonaceous materials were obtained through solution combustion process of tamarind shell in the presence of urea and ammonium nitrate, and all of them were tested for Co removal. The effect of temperature (from 600 to 1000°C) and water volume on surface texture of carbonaceous material and its adsorptive capacity was evaluated. Scanning electron microscope, Fourier transform infrared spectroscopy, X-ray powder diffraction, and Brunauer-Emmett-Teller (BET) model were used to characterize the obtained carbonaceous material before applying for the removal of cobalt. The point of zero charge was also determined. The results indicate that BET-specific surface areas ranged from 6.40 to 216.72 m2g-1 for the carbonaceous materials obtained at 600, 700, 800, 900, and 1000°C. The one obtained at 900°C (CombTSF900) was found to be the most effective adsorbent for the removal of Co(II) ions from aqueous solutions, with a maximum sorption capacity (Qmax) of 43.56 mg/g. Carbonaceous material obtained through the solution combustion process improves morphological characteristics of adsorbent in a short time, and could be used as an alternative method for the removal of cobalt.


Assuntos
Cobalto , Tamarindus , Poluentes Químicos da Água , Adsorção , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura , Purificação da Água , Difração de Raios X
18.
J Environ Sci (China) ; 57: 418-428, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28647264

RESUMO

A series of MgO-based adsorbents were prepared through solution-combustion synthesis and ball-milling process. The prepared MgO-based powders were characterized using X-ray diffraction, scanning electron microscopy, N2 physisorption measurements, and employed as potential adsorbents for CO2 adsorption. The influence of structural and textural properties of these adsorbents over the CO2 adsorption behaviour was also investigated. The results showed that MgO-based products prepared by solution-combustion and ball-milling processes, were highly porous, fluffy, nanocrystalline structures in nature, which are unique physico-chemical properties that significantly contribute to enhance their CO2 adsorption. It was found that the MgO synthesized by solution combustion process, using a molar ratio of urea to magnesium nitrate (2:1), and treated by ball-milling during 2.5hr (MgO-BM2.5h), exhibited the maximum CO2adsorption capacity of 1.611mmol/g at 25°C and 1atm, mainly via chemisorption. The CO2 adsorption behaviour on the MgO-based adsorbents was correlated to their improved specific surface area, total pore volume, pore size distribution and crystallinity. The reusability of synthesized MgO-BM2.5h was confirmed by five consecutive CO2 adsorption-desorption times, without any significant loss of performance, that supports the potential of MgO-based adsorbent. The results confirmed that the special features of MgO prepared by solution-combustion and treated by ball-milling during 2.5hr are favorable to be used as effective MgO-based adsorbent in post-combustion CO2 capture technologies.


Assuntos
Dióxido de Carbono/química , Óxido de Magnésio/química , Modelos Químicos , Adsorção , Microscopia Eletrônica de Varredura , Porosidade
19.
J Environ Manage ; 156: 121-7, 2015 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-25841193

RESUMO

New carbonaceous materials were obtained using a fast aqueous solution combustion process from mixtures of exhausted coffee, ammonium nitrate (oxidizer) and urea (fuel) heated at 600, 700, 800 or 900 °C. The resulting powders were effective adsorbents for removing Co(II) and Cd(II) from aqueous solutions. Exhausted coffee was also calcined at different temperatures and compared. The products were characterized, and the obtained carbons had BET specific surface areas of 114.27-390.85 m(2)/g and pore diameters of 4.19 to 2.44 nm when the temperature was increased from 600 to 800 °C. Cobalt and cadmium adsorption by the carbonaceous materials was correlated with the maximum adsorption capacities and specific surface areas of the materials. The method reported here is advantageous because it only required 5 min of reaction to improve the textural properties of carbon obtained from exhausted coffee, which play an important role in the material's cobalt and cadmium adsorption capacities.


Assuntos
Cádmio/química , Carbono/isolamento & purificação , Cobalto/química , Café/química , Eliminação de Resíduos/métodos , Poluentes Químicos da Água/química , Purificação da Água/métodos , Adsorção , Oxirredução , Temperatura
20.
Heliyon ; 10(14): e34427, 2024 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-39104478

RESUMO

This study focuses on the solution combustion approach to examine the nanostructures of undoped and doped ZnO with different concentrations of Al (0.1 % and 0.2 %). Various physical techniques were utilized to characterize the synthesized nanoparticles. X-ray diffraction (XRD) revealed the crystalline materials, while scanning electron microscopy (SEM) with energy-dispersive X-ray (EDX) findings confirmed the products with particle size and the insertion of Al into the ZnO lattice. Fourier-transform infrared spectra (FTIR) confirmed the presence of different functional groups in the obtained material. The results indicate that Al-doped ZnO (Al-ZnO) nanoparticles show promising properties for optoelectronics and photoluminescence. Photoluminescence analysis indicated that an increase in Al3+ (0.2 %) concentration resulted in a decrease in peak intensity and an increase in the full width at half maximum. The band gap was calculated using the Taucs plot. The study also highlights the effectiveness of Zn1-xAlxO nanostructures in degrading organic pollutants, particularly in adsorbing Malachite Green (MG) dye. Among the samples, the 0.2 % Al-doped ZnO exhibited superior dye degradation efficiency due to its enhanced adsorption capacity and smaller particle size, as evidenced by multilayer adsorption capacity and chemisorption during the degradation process. This study provides valuable insights into the potential applications of Al-doped ZnO nanoparticles in various environmental and technological fields, emphasizing their significance in the degradation of organic pollutants.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA