Heterogeneous photocatalytic Cr(VI) reduction with short and long nanotubular TiO 2 coatings prepared by anodic oxidation

Vera, María L.; Traid, Hernán Darío; Henrikson, Edgard Rubén; Ares, Alicia Esther; Litter, Marta I.

doi:10.1016/j.materresbull.2017.08.013

Cited by 29 publications

(16 citation statements)

References 59 publications

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“…The pseudo‐first order kinetic regime can be attributed to the higher surface areas of the photocatalyst that cannot be saturated by adsorbed chromium, making the reduction rate dependent on the Cr(VI) concentration in solution, as in the case of the homogeneous systems. Similar k values for Cr(VI) transformation were reported for long nanotubular TiO 2 coatings made by anodic oxidation 21…”

Section: Resultssupporting

confidence: 80%

“…To overcome this drawback, several ways of immobilizing TiO 2 on surfaces have been adopted. [17][18][19][20][21] Thus, this article is aimed at the comparison of the photocatalytic activity of nanoparticle-TiO 2 layers applied on glass sponges with a variation of pore size and consequent different specific surfaces necessary for greater catalytic activity. The relationship of the geometric parameters of the sponges such as pores per inch (ppi) and porosity and the TiO 2 amount on the sponges was investigated.…”

Section: Introductionmentioning

confidence: 99%

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Morphological characterization and photocatalytic efficiency measurements of pure silica transparent open‐cell sponges coated with TiO₂

Löffler

Altermann

Bucharsky

et al. 2020

Int J Applied Ceramic Tech

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Transparent glass sponges are a new class of materials that can potentially be used for effective light distribution in photocatalytic applications. In this work, transparent glass sponges are prepared by the polymer replica technique and coated with TiO2 to obtain a highly efficient photocatalytic material. Necessary conditions for obtaining transparent open‐celled glass sponges are presented. The structure is characterized by employing light microscopy and scanning electron microscopy. In addition, µ‐computer tomography (µ‐CT) volume image analysis was performed that allows the calculation of geometrical parameters like pore size and specific surface area (SSA) of the structure, required for application of the new material. For photocatalytic application, the sponges have been coated with titanium dioxide (TiO2) by immersion in a suspension of TiO2 nanoparticles. The activity of the resulting coatings has been tested with the model reaction of transformation of Cr(VI) to Cr(III) in aqueous solutions in the presence of EDTA at pH 2. The reaction kinetics could be adjusted to a pseudo‐first order reaction and the obtained rate constants have been employed to evaluate the photocatalytic activity. The activity of the sponges has been compared with that of samples of glass plates coated with TiO2; it has been found that the sponges exhibited a higher catalytic activity than the glass plates. The photocatalytic activity increased with the porosity of the sponges, and the optimum sample was determined based on its photocatalytic performance and its mechanical stability. The results are promissory for application in photoreactors for transformation of pollutants in water and air decontamination.

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Section: Resultssupporting

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Morphological characterization and photocatalytic efficiency measurements of pure silica transparent open‐cell sponges coated with TiO₂

Löffler

Altermann

Bucharsky

et al. 2020

Int J Applied Ceramic Tech

Self Cite

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“…The photocatalytic reduction of low concentrations of Cr(VI) to the less harmful Cr(III) has been proved to be efficient and can be employed in combination or as an alternative to other conventional processes in order to reduce the operational costs of decontamination [33,34]. Ethylenediaminetetraacetic acid (EDTA) has been used in several works as an electron donor (sacrificial synergetic agent) to accelerate the Cr(VI) reduction, and the Cr(VI)/EDTA system has been shown to be appropriate to determine the photocatalytic activity of different materials [33,[35][36][37][38][39].…”

Section: Introductionmentioning

confidence: 99%

Photocatalytic and mechanical properties of immobilized nanotubular TiO2 photocatalysts obtained by anodic oxidation: a novel combined analysis

Dwojak

Vera

Traid

et al. 2022

Photochem Photobiol Sci

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The photocatalytic and mechanical performance of TiO 2 nanotubular coatings obtained by anodic oxidation of commercial titanium, using an NH 4 F and 3.5% v/v water in ethylene glycol solution as electrolyte was investigated. After the anodization, the coatings were thermally treated at 450 °C for 2 h. The effects of the anodizing voltage (40-80 V) and NH 4 F concentration (0.06, 0.15, 0.27 M) on the formation of the nanotube arrays were evaluated. Nanotube diameters (57 to 114 nm), wall thicknesses (4 to 13 nm), and lengths (5 to 17 µm) increased with the anodizing voltage and the NH 4 F concentration. The photocatalysts were characterized by scanning electron microscopy, glancing incidence X-ray diffraction, and UV-Vis diffuse reflectance spectroscopy. The mechanical properties of the photocatalysts were determined: adhesion using the tape test (ASTM D3359) and erosion resistance through a 3 h accelerated test. The photocatalytic activity of the nanotubes under UV irradiation was evaluated using hexavalent chromium (Cr(VI)) in the presence of ethylenediaminetetraacetic acid (EDTA), using a 1.25 EDTA/Cr(VI) molar ratio solution at pH 2. A complete Cr(VI) transformation after 3 h of irradiation was obtained for all samples, with a better performance than that of an immobilized P25 sample. The photocatalyst obtained with 0.27 M NH 4 F at 40 V presented a good behavior in adherence and erosion resistance, together with a very good photocatalytic activity. This novel analysis, combining photocatalytic and mechanical tests, proved that the new TiO 2 nanotubular coatings could be successfully used as immobilized photocatalysts in photoreactors for water treatment.

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“…For example, copper anodizing contributes to such important applications as CO 2 electrochemical reduction [24], methanol fuel cells [25], photocatalytic water splitting [26] and microplastic decomposition [27]. Anodic titania is used in such important aspects as photocatalytic water splitting [28], hazardous compounds neutralization (e.g., Bisphenol A and Rhodamine B [29], or chromates [30]) and microplastic decomposition [31]. Moreover, anodic titania is also gaining the attention of researchers as a drug-releasing platform [32] and sensor [33].…”

Section: Introductionmentioning

confidence: 99%

Incorporation of Ions into Nanostructured Anodic Oxides—Mechanism and Functionalities

2021

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Anodic oxidation of metals leads to the formation of ordered nanoporous or nanotubular oxide layers that contribute to numerous existing and emerging applications. However, there are still numerous fundamental aspects of anodizing that have to be well understood and require deeper understanding. Anodization of metals is accompanied by the inevitable phenomenon of anion incorporation, which is discussed in detail in this review. Additionally, the influence of anion incorporation into anodic alumina and its impact on various properties is elaborated. The literature reports on the impact of the incorporated electrolyte anions on photoluminescence, galvanoluminescence and refractive index of anodic alumina are analyzed. Additionally, the influence of the type and amount of the incorporated anions on the chemical properties of anodic alumina, based on the literature data, was also shown to be important. The role of fluoride anions in d-electronic metal anodizing is shown to be important in the formation of nanostructured morphology. Additionally, the impact of incorporated anionic species, such as ruthenites, and their influence on anodic oxides formation, such as titania, reveals how the phenomenon of anion incorporation can be beneficial.

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Heterogeneous photocatalytic Cr(VI) reduction with short and long nanotubular TiO 2 coatings prepared by anodic oxidation

Cited by 29 publications

References 59 publications

Morphological characterization and photocatalytic efficiency measurements of pure silica transparent open‐cell sponges coated with TiO₂

Morphological characterization and photocatalytic efficiency measurements of pure silica transparent open‐cell sponges coated with TiO₂

Photocatalytic and mechanical properties of immobilized nanotubular TiO2 photocatalysts obtained by anodic oxidation: a novel combined analysis

Incorporation of Ions into Nanostructured Anodic Oxides—Mechanism and Functionalities

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Heterogeneous photocatalytic Cr(VI) reduction with short and long nanotubular TiO 2 coatings prepared by anodic oxidation

Cited by 29 publications

References 59 publications

Morphological characterization and photocatalytic efficiency measurements of pure silica transparent open‐cell sponges coated with TiO2

Morphological characterization and photocatalytic efficiency measurements of pure silica transparent open‐cell sponges coated with TiO2

Photocatalytic and mechanical properties of immobilized nanotubular TiO2 photocatalysts obtained by anodic oxidation: a novel combined analysis

Incorporation of Ions into Nanostructured Anodic Oxides—Mechanism and Functionalities

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Morphological characterization and photocatalytic efficiency measurements of pure silica transparent open‐cell sponges coated with TiO₂

Morphological characterization and photocatalytic efficiency measurements of pure silica transparent open‐cell sponges coated with TiO₂