Niobium-Titanium-Based Photocatalysts: Its Potentials for Free Cyanide Oxidation in Residual Aqueous Effluent

López, Aida Liliana Barbosa; Castro, Isel

doi:10.3389/fchem.2020.00099

Cited by 8 publications

(3 citation statements)

References 56 publications

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“…Despite each method providing different order of magnitude of shifting, the shift is still not well significant and needs to be improved. The main issue is related to the large size obtained of Nb/TiO 2 and the formation of Nb-O clusters that increase the charge-carrier recombination rate [20,21].…”

Section: Introductionmentioning

confidence: 99%

Photocatalytic Degradation of Phenol Red in Water on Nb(x)/TiO2 Nanocomposites

2022

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In this paper, the photocatalytic effect of Nb(x)/TiO2 nanocomposites on the degradation of phenol red (PR) was studied. Nb(x)/TiO2 nanocomposites are fabricated by a simple sol-gel route with new experimental conditions. The structural and optical properties were determined using high transmission electron microscopy (HRTEM), X-ray diffraction, Raman spectroscopy, photoluminescence, and UV-vis absorbance spectroscopy. Compared to pure anatase TiO2, the recently fabricated Nb(x)/TiO2 nanocomposite has a shift in the optical band edge to the visible wavelength. Consequently, it has high performance in adsorption capacity and photocatalytic activities. A time of 160 min has been observed to be suitable for mostly degradable 20 mgL−1 of phenol red on Nb(2.0)/TiO2 composite. The kinetic results were in good agreement with the first-order kinetic model at different concentrations. In addition, the results showed that the addition of Nb led to a significant degradation process. The decomposition of phenol red pollutants showed a synergistic effect of the Nb(2.0)/TiO2 nanocomposites on wastewater treatment.

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Section: Introductionmentioning

confidence: 99%

Photocatalytic Degradation of Phenol Red in Water on Nb(x)/TiO2 Nanocomposites

2022

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“…The X-ray diffractograms of the Nb 2 O 5 support and Na/ Nb 2 O 5 catalyst (panels a and b of Figure 2) indicated that Nb 2 O 5 without any thermal treatment corresponded to an amorphous material according to a typical profile without peaks, as reported in the literature, 18,19 while calcined Nb 2 O 5 showed the presence of crystalline phases in the support (Figure 2a), indicating that changes in the structure occurred as a result of atom rearrangement by the applied thermal treatment. The Na/Nb 2 O 5 spectrum showed pronounced peaks representing the crystalline phases dispersed in the amorphous phase (Figure 2b), enhancing the material crystallinity.…”

Section: Resultsmentioning

confidence: 99%

Use and Reusability of the Na/Nb₂O₅ Catalyst in the Ethanolysis of Different Feedstocks for Biofuel Production: Confirmation of Heterogeneity of the Catalyst

et al. 2020

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Niobium oxide impregnated with sodium (Na/Nb2O5) was used as a heterogeneous catalyst to produce biofuel from conventional raw materials, such as soybean oil and beef tallow, and non-conventional feedstocks, including andiroba, babassu, coconut, crambe, macaw palm, palm, palm kernel, and jatropha oils. The trials were performed at fixed conditions using 10% catalyst at 78.5 °C under stirring (600 rpm) for 5 h. On the basis of the results generated by gas and liquid chromatographies, high catalytic activity was found for all tested feedstocks, revealing yields higher than 95%. The purity of the ethyl esters was validated by thermogravimetric analysis and nuclear magnetic resonance. The Na/Nb2O5 catalyst performed efficiently, converting the fatty acids present in the lipid raw materials to the ethyl esters, and showed high stability in consecutive batches, generating products that meet the specificity of international standards. The heterogeneity of the catalyst was also confirmed by determining the sodium concentration in both biodiesel and the catalyst after consecutive batch runs.

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“…Many efforts have recently been made in semiconductors' doping, mixed oxides synthesis, and heterojunction formation technologies to improve photocatalytic activity in organic pollutants degradation [5]. TiO 2 -Nb 2 O 5 -based photocatalysts have already been applied in the degradation of compounds such as anti-inflammatories [16], dyes [17], herbicides [18], and cyanide oxidation [19]. Although pure titanium dioxide performs better than pure niobium pentoxide in some cases [20,21], studies indicate that the combination of these two semiconductors can bring benefits, such as increased absorption of visible light radiation, considerable improvement in the photocatalytic activity of TiO 2 [22,23], increased surface acidity of the catalysts, [23], greater sensitivity of the composite to UV radiation [18], and better charge separation in the heterojunction [24].…”

Section: Introductionmentioning

confidence: 99%

N-Doped TiO2-Nb2O5 Sol–Gel Catalysts: Synthesis, Characterization, Adsorption Capacity, Photocatalytic and Antioxidant Activity

Fuziki,

Ribas,

Abreu

et al. 2023

Catalysts

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TiO2-based semiconductors are formidable photocatalysts for redox reaction applications. Although N-doped TiO2-Nb2O5 catalysts have already been explored in the literature, studies on their antioxidant activity are scarce, and systematic investigations on the effects of synthesis parameters over a wide range of %Nb and NH4OH concentrations are limited. In addition, the relationship between optimal pH and %Nb has not yet been adequately explored. In the present work, the sol–gel synthesis of N-doped TiO2-Nb2O5 catalysts was optimized using a design of experiments approach focused on photocatalysis, adsorption, and antioxidant applications. The samples were characterized by TGA, SEM/EDS, XRD, PZC tests, photoacoustic spectroscopy, and N2-adsorption/desorption experiments. The salicylic acid (SA) degradation tests and DPPH radical scavenging assays demonstrated the superior photocatalytic activity (up to 72.9% SA degradation in 30 min, pH 5) and antioxidant capacity (IC50 = 88.9 μg mL−1) of pure TiO2 compared to the N-doped TiO2-Nb2O5 catalysts. The photocatalytic activity, however, proved to be intensely dependent on the pH and %Nb interaction, and at pH 3, the 25Nb-1N-400 catalyst promoted more significant SA degradation (59.9%) compared to pure TiO2 (42.8%). In the methylene blue (MB) adsorption tests, the catalysts N-doped TiO2-Nb2O5 showed removals at least seven times greater than TiO2 catalysts without Nb.

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Niobium-Titanium-Based Photocatalysts: Its Potentials for Free Cyanide Oxidation in Residual Aqueous Effluent

Cited by 8 publications

References 56 publications

Photocatalytic Degradation of Phenol Red in Water on Nb(x)/TiO2 Nanocomposites

Photocatalytic Degradation of Phenol Red in Water on Nb(x)/TiO2 Nanocomposites

Use and Reusability of the Na/Nb₂O₅ Catalyst in the Ethanolysis of Different Feedstocks for Biofuel Production: Confirmation of Heterogeneity of the Catalyst

N-Doped TiO2-Nb2O5 Sol–Gel Catalysts: Synthesis, Characterization, Adsorption Capacity, Photocatalytic and Antioxidant Activity

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Niobium-Titanium-Based Photocatalysts: Its Potentials for Free Cyanide Oxidation in Residual Aqueous Effluent

Cited by 8 publications

References 56 publications

Photocatalytic Degradation of Phenol Red in Water on Nb(x)/TiO2 Nanocomposites

Photocatalytic Degradation of Phenol Red in Water on Nb(x)/TiO2 Nanocomposites

Use and Reusability of the Na/Nb2O5 Catalyst in the Ethanolysis of Different Feedstocks for Biofuel Production: Confirmation of Heterogeneity of the Catalyst

N-Doped TiO2-Nb2O5 Sol–Gel Catalysts: Synthesis, Characterization, Adsorption Capacity, Photocatalytic and Antioxidant Activity

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Use and Reusability of the Na/Nb₂O₅ Catalyst in the Ethanolysis of Different Feedstocks for Biofuel Production: Confirmation of Heterogeneity of the Catalyst