Ceramic photocatalytic membranes for water filtration under UV and visible light

Athanasekou, Chrysoula; Moustakas, Nikolaos G.; Morales‐Torres, Sergio; Pastrana‐Martínez, Luisa M.; Figueiredo, José L.; Faria, Joaquim L.; Silva, Adrián M.T.; Doña-Rodrı́guez, J.M.; Romanos, George E.; Falaras, Polycarpos

doi:10.1016/j.apcatb.2014.11.021

Cited by 141 publications

(55 citation statements)

References 41 publications

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“…The commercialisation of photocatalysis technology has gained significant interest in recent decades. The photocatalysis concept has been successfully established for various commercial products, such as cement [2], air purifier [3], paints [4], water filter [5], deodorisers [6], mosquito repellent fabrics [7], and antimicrobial doping on the phase stability of anatase, formation of oxygen vacancies, and the photocatalytic activity to show that Mo doping could preserve the anatase content at high calcination temperature and thus enhance the activity of TiO 2 . A comprehensive analysis on the relationship between the dopant concentration and the surface characteristics of TiO 2 is discussed.…”

Section: Introductionmentioning

confidence: 99%

Mo doped TiO₂: impact on oxygen vacancies, anatase phase stability and photocatalytic activity

et al. 2020

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This work outlines an experimental and theoretical investigation of the effect of molybdenum (Mo) doping on the oxygen vacancy formation and photocatalytic activity of TiO 2 . Analytical techniques such as x-ray diffraction (XRD), Raman, x-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) were used to probe the anatase to rutile transition (ART), surface features and optical characteristics of Mo doped TiO 2 (Mo-TiO 2 ). XRD results showed that the ART was effectively impeded by 2 mol% Mo doping up to 750°C, producing 67% anatase and 33% rutile. Moreover, the crystal growth of TiO 2 was affected by Mo doping via its interaction with oxygen vacancies and the Ti-O bond. The formation of Ti-O-Mo and Mo-Ti-O bonds were confirmed by XPS results. Phonon confinement, lattice strain and non-stoichiometric defects were validated through the Raman analysis. DFT results showed that, after substitutional doping of Mo at a Ti site in anatase, the Mo oxidation state is Mo 6+ and empty Mo-s states emerge at the titania conduction band minimum. The empty Mo-d states overlap the anatase conduction band in the DOS plot. A large energy cost, comparable to that computed for pristine anatase, is required to reduce Mo-TiO 2 through oxygen vacancy formation. Mo 5+ and Ti 3+ are present after the oxygen vacancy formation and occupied states due to these reduced cations emerge in the energy gap of the titania host. PL studies revealed that the electron-hole recombination process in Mo-TiO 2 was exceptionally lower than that of TiO 2 anatase and rutile. This was ascribed to introduction of 5s gap states below the CB of TiO 2 by the Mo dopant. Moreover, the photo-generated charge carriers could easily be trapped and localised on the TiO 2 surface by Mo 6+ and Mo 5+ ions to improve the photocatalytic activity. coatings [8,9]. The most commonly existing crystalline polymorphs of TiO 2 are anatase, rutile and brookite [10][11][12]. Anatase is accepted to be the more active phase of TiO 2 and is preferred by the ceramic industries to fabricate light active antimicrobial indoor building materials such as ceramics, glass, tiles and sanitary surfaces [13,14]. This requires thermal stability of the anatase phase under typical ceramic processing conditions. TiO 2 anatase is mainly fabricated at low calcination temperatures (∼500°C) to prevent the anatase to rutile phase transition (ART) [15][16][17], which produces the less photo-active rutile phase. The photo-activity of anatase arises from its appropriate band edge positions, electron affinity, ionisation potential, and the long lifetime of charge carriers [10,12,18]. Moreover, transient photo-conductance analysis has revealed that the electron-hole recombination phenomena in anatase (101) phase is much slower compared to rutile (110), which is credited in part to the indirect band gap of anatase [11,19].The unit cells of anatase and rutile phases are composed of TiO 6 octahedra with titanium atoms at the centre and oxygen atoms at the vertices [20]. Both anatase and rutile have a t...

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Section: Introductionmentioning

confidence: 99%

Mo doped TiO₂: impact on oxygen vacancies, anatase phase stability and photocatalytic activity

et al. 2020

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“…As previously described [27], this irradiation density was achieved by four (4) near-UV radiation sources (lamps of 9 W, 315À380, Phillips UVA) with a peak at 365 nm and a length of 100 mm. Four (4) visible lamps of 9 W (Osram DULUX S 9W/21-840 G23 LUMILUXCool White, length 10 mm) were used to achieve a Vis light irradiation density of 7.2 mW cm À2 [28]. The UV and white light lamps were accommodated vertically on to two moving bases of half-circle shape that were surrounding the reaction vial, bringing each light source at a distance of 5 cm from it and were covered on their periphery by thick aluminum foil for light intensity boosting.…”

Section: Photocatalytic Cr(vi) Reductionmentioning

confidence: 99%

Photocatalytic degradation of hexavalent chromium emerging contaminant via advanced titanium dioxide nanostructures

Athanasekou

Romanos

Papageorgiou

et al. 2017

Chemical Engineering Journal

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“…Thus, TiO 2 is capable to use only less than about 5% of the solar energy, which is in the UV range. On these bases, the development of photocatalysts that are able to utilize visible light represents a challenge in view of large-scale application of PMR systems, permitting the use of a greener light source (the sun) [26,27]. When considering that the quantum efficiency of the photocatalytic processes usually decreases by increasing the intensity of the radiation, the preparation of photocatalysts active under visible light is convenient only when the quantum efficiency remains relatively high, resulting in a wide use of photons from visible light.…”

Section: Photocatalyst Type and Its Characteristicsmentioning

confidence: 99%

Photocatalytic Membranes in Photocatalytic Membrane Reactors

et al. 2018

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The present work gives a critical overview of the recent progresses and new perspectives in the field of photocatalytic membranes (PMs) in photocatalytic membrane reactors (PMRs), thus highlighting the main advantages and the still existing limitations for large scale applications in the perspective of a sustainable growth. The classification of the PMRs is mainly based on the location of the photocatalyst with respect to the membranes and distinguished in: (i) PMRs with photocatalyst solubilized or suspended in solution and (ii) PMRs with photocatalyst immobilized in/on a membrane (i.e., a PM). The main factors affecting the two types of PMRs are deeply discussed. A multidisciplinary approach for the progress of research in PMs and PMRs is presented starting from selected case studies. A special attention is dedicated to PMRs employing dispersed TiO 2 confined in the reactor by a membrane for wastewater treatment. Moreover, the design and development of efficient photocatalytic membranes by the heterogenization of polyoxometalates in/on polymeric membranes is discussed for applications in environmental friendly advanced oxidation processes and fine chemical synthesis.The Process Intensification (PI) strategy [5,6] is recognized as an efficient tool for the realization of this sustainable growth. The PI strategy comprises an innovative equipment design and process development methods, being able to improve manufacturing and processing, by decreasing production costs, equipment size, energy consumption, waste generation, while improving process efficiency, remote control, information fluxes, and process flexibility [7]. MRs are specific example of reactive separations well responding to the requests of the PI strategy, coupling a reaction with a membrane separation process, not only at equipment level, but by realizing functional synergies between the operations involved [6]. This synergic combination can have several advantages in comparison with traditional reactors depending on the specific functions performed by the membrane [8]. With respect to traditional reactive separations (e.g., reactive distillation, reactive adsorption, reactive crystallization/precipitation), MRs have the advantage to use intrinsically more clean and energy-efficient separation routes [6]. Membrane separations are in fact typically characterized by lower operating temperature, in comparison with thermal separation processes, such as distillation, and they might offer a solution in the case of catalysts or products with a limited thermal stability. Additionally, membrane separation processes are able to separate nonvolatile components by a difference in dimensions, charge, or volatility.The selective transport of the products and/or the reagents through the membrane can increase the yield and/or the selectivity of some processes. Typical examples are esterification and de-hydrogenation reactions (thermodynamically controlled reactions), in which the removal of water or hydrogen, respectively, increases the reaction yield. The extractio...

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Ceramic photocatalytic membranes for water filtration under UV and visible light

Cited by 141 publications

References 41 publications

Mo doped TiO₂: impact on oxygen vacancies, anatase phase stability and photocatalytic activity

Mo doped TiO₂: impact on oxygen vacancies, anatase phase stability and photocatalytic activity

Photocatalytic degradation of hexavalent chromium emerging contaminant via advanced titanium dioxide nanostructures

Photocatalytic Membranes in Photocatalytic Membrane Reactors

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Ceramic photocatalytic membranes for water filtration under UV and visible light

Cited by 141 publications

References 41 publications

Mo doped TiO2: impact on oxygen vacancies, anatase phase stability and photocatalytic activity

Mo doped TiO2: impact on oxygen vacancies, anatase phase stability and photocatalytic activity

Photocatalytic degradation of hexavalent chromium emerging contaminant via advanced titanium dioxide nanostructures

Photocatalytic Membranes in Photocatalytic Membrane Reactors

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Product

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Mo doped TiO₂: impact on oxygen vacancies, anatase phase stability and photocatalytic activity

Mo doped TiO₂: impact on oxygen vacancies, anatase phase stability and photocatalytic activity