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In this work, photocatalytic materials constituted by Cr-doped TiO2 (Cr-TiO2) decorated with noble metals show high effectiveness in the mineralization of Acid Orange 7 (AO7) and in the disinfection of real river water. The materials were... more
In this work, photocatalytic materials constituted by Cr-doped TiO2 (Cr-TiO2) decorated with noble metals show high effectiveness in the mineralization of Acid Orange 7 (AO7) and in the disinfection of real river water. The materials were firstly obtained by sol-gel method to get Cr-TiO2 that was subsequently modified by photochemical deposition of Ag or Pd nanoparticles (Ag/Cr-TiO2, Pd/Cr-TiO2). Chemical-physical characterization results evidenced that the noble metals were homogeneously distributed on the Cr-TiO2 surface. By using Pd(0.25%)/Cr-TiO2, the AO7 discoloration efficiency was about 91.4% after only 60 min of visible irradiation, which can be due to the lowest band gap of this material. Moreover, nitrates, chlorides, total hardness, and coliform bacteria content significantly decreased after the treatment of real river water samples (that is contaminated by industrial and domestic effluents) under UV and visible light irradiation in the presence of TiCrOx decorated with n...
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Improving visible light active photocatalyst performances through photoactive supports in the photocatalytic removal of emerging contaminant
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Abstract This chapter starts with an introduction to photocatalysts active under visible light. Then, the different doping modes for TiO2 are discussed. For its importance, nitrogen-doped TiO2 is described in great detail: in particular... more
Abstract This chapter starts with an introduction to photocatalysts active under visible light. Then, the different doping modes for TiO2 are discussed. For its importance, nitrogen-doped TiO2 is described in great detail: in particular the synthesis of nitrogen-doped TiO2 was reported, focusing on the optimization of nitrogen-doped TiO2 photocatalytic activity using ammonia as nitrogen source. Finally, some applications of nitrogen-doped TiO2 in environmental remediation are presented, discussing the characteristic of structured supported photocatalysts, and briefly the photocatalytic performances when nitrogen-doped TiO2 is supported on glass spheres or on phosphors, luminescent materials able to convert light energy into photons of different energy. Nitrogen-doped TiO2 coupled with up-conversion phosphors and nitrogen-doped TiO2 coupled with down-conversion phosphors preparation and behaviors are summarized.
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Waters coming from dyeing and finishing processes by leather industries produce serious problems because they contain dyes and other pollutants. Toxic and recalcitrant for the environmental, these pollutants are difficult to remove by... more
Waters coming from dyeing and finishing processes by leather industries produce serious problems because they contain dyes and other pollutants. Toxic and recalcitrant for the environmental, these pollutants are difficult to remove by conventional treatments. For this reason, the heterogeneous photocatalysis is a promising and efficient method to remove them. ZnO is an excellent and promising photocatalytic material to oxidize organic pollutants into CO2 and H2O. In order to enhance the photocatalytic activity of ZnO, in this work, the doping of ZnO with praseodymium (Pr) has been realized and studied in the photocatalytic treatment of dyeing and finishing waters with a total organic carbon (TOC) values in the range 540-1200 mg·L-1. ZnO particles doped with Pr were prepared by a modified precipitation method and characterized by different techniques (XRD, Raman, UV-Vis DRS). The photocatalytic activities of the synthesized samples were investigated under UV light with a specifically...
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Photocatalytic Removal of Phenol by Ferromagnetic NTiO2/SiO2/Fe3O4 Nanoparticles in presence of Visible Light Irradiation Vincenzo Vaiano, Olga Sacco, Diana Sannino, Marco Stoller, Paolo Ciambelli, Angelo Chianese Department of Industrial... more
Photocatalytic Removal of Phenol by Ferromagnetic NTiO2/SiO2/Fe3O4 Nanoparticles in presence of Visible Light Irradiation Vincenzo Vaiano, Olga Sacco, Diana Sannino, Marco Stoller, Paolo Ciambelli, Angelo Chianese Department of Industrial Engineering, University of Salerno, Via Giovanni Paolo II 132, 84084 Fisciano (SA), Italy Department of Chemical Material Environmental Engineering, University of Rome “La Sapienza”, Via Eudossiana 18, 00184 Rome, Italy. vvaiano@unisa.it
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The aim of the work was to increase the photoactivity of N-doped TiO2 photocatalyst, active in visible light region, through the improving of the illumination efficiency. Microradiators like phosphors (namely, ZPS) which absorb an... more
The aim of the work was to increase the photoactivity of N-doped TiO2 photocatalyst, active in visible light region, through the improving of the illumination efficiency. Microradiators like phosphors (namely, ZPS) which absorb an electromagnetic radiation by the external light source (UV) and, with no time delay, emit visible light, opportunely selected to be able to excite N-doped TiO2 photocatalyst. Preliminary investigations were performed on physical mixtures of phosphors and N-doped TiO2, evaluating the decolourization of methylene blue (MB). The simultaneous presence of N-doped TiO2 and light carriers showed an increased decolourization activity, reaching about 100 % with a total TOC removal after 3 h of irradiation. To get core-shell photocatalysts, N-doped TiO2 was supported on ZPS (NTiO2-ZPS) by a modified sol–gel method. The content of N-doped TiO2 was varied in the range 5-50 wt % to find an optimum loading. The photocatalytic activity of NTiO2-ZPS was evaluated for the ...
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In this work, TiO2-Ag-zeolite was supported on porous ceramic tiles to enhance the self-cleaning properties. The influence on adsorption and photocatalytic properties of the anchored composite with respect to a coating with only TiO2 has... more
In this work, TiO2-Ag-zeolite was supported on porous ceramic tiles to enhance the self-cleaning properties. The influence on adsorption and photocatalytic properties of the anchored composite with respect to a coating with only TiO2 has been evaluated. Functionalized tiles were obtained through a method that involves a sol- gel preparation followed by calcination at 550 °C for 2 h and different samples at different titanium and silver surface loads were prepared. The verification of the self-cleaning properties was conducted through adsorption and photocatalytic tests realized using aqueous solutions containing methylene blue (MB).Characterization results evidenced that the deposition method induced the formation of TiO2/Ag-zeolite layer, strongly adherent to the tile surface, in which TiO2 is present in anatase phase. The photocatalytic performances are strongly influenced by the amount of TiO2-Ag-zeolite composite deposited on the tile surface.
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Photocatalytic Conversion of Glucose to H2 over LaFeO3 Perovskite Nanoparticles Giuseppina Iervolino, Vincenzo Vaiano, Diana Sannino, Luigi Rizzo, Paolo Ciambelli a Department of Industrial Engineering, University of Salerno, Via Giovanni... more
Photocatalytic Conversion of Glucose to H2 over LaFeO3 Perovskite Nanoparticles Giuseppina Iervolino, Vincenzo Vaiano, Diana Sannino, Luigi Rizzo, Paolo Ciambelli a Department of Industrial Engineering, University of Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano (SA), Italy b Department of Civil Engineering, University of Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano (SA) Italy giiervolino@unisa.it
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Abstract Imogolite-like nanomaterials were tested as heterogeneous catalysts for the photo-catalytic degradation of tartrazine (a food dye recalcitrant to biodegradation and responsible of allergic and/or intolerance reactions) in the... more
Abstract Imogolite-like nanomaterials were tested as heterogeneous catalysts for the photo-catalytic degradation of tartrazine (a food dye recalcitrant to biodegradation and responsible of allergic and/or intolerance reactions) in the presence of H 2 O 2 . Methyl-imogolite, a hybrid organic/inorganic material with chemical composition (OH) 3 Al 2 O 3 SiCH 3 , occurs as single-walled nanotubes with an inner surface lined by Si-CH 3 groups and an aluminum oxo-hydroxide outer surface, where octahedral Al 3+ ions may be isomorphically substituted by Fe 3+ ions. Besides bare methyl-imogolite, novel Fe doped nanotubes (with nominal composition (OH) 3 Al 2-x Fe x O 3 SiCH 3 , where x = 0.025 or 0.050) were prepared by ion exchange of preformed methyl-imogolite with FeCl 3 × 6H 2 O in water. Physico-chemical characterization of the materials showed that Fe doping positively modifies nanotubes light absorption capacity by lowering the band gap of methyl-imogolite from 4.9 eV to 2.4 eV. At higher Fe content (sample with nominal composition (OH) 3 Al 1.950 Fe 0.050 O 3 SiCH 3 ), some Fe oxo-hydroxide clusters form, due to the natural tendency of Fe to form aggregates. Photo-degradation tests of tartrazine show that both bare and Fe-doped methyl-imogolite efficiently remove the dye from aqueous mixtures through different mechanisms. With bare methyl-imogolite, under UV light almost 65% Total Organic Carbon (TOC) is removed within 2 h, likely due to the formation of reactive AlOOH groups promptly generating HO radicals. With sample having nominal composition (OH) 3 Al 1.975 Fe 0.025 O 3 SiCH 3 , Fe 3+ species undergo efficient photo-Fenton reaction under UV light, leading to 90% TOC removal after 2 h. Conversely, the Fe oxo-hydroxide clusters at nanotubes outer surface likely worsen the photo-Fenton activity of the sample with (OH) 3 Al 1.950 Fe 0.050 O 3 SiCH 3 nominal composition as far as the TOC removal is concerned.
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Dyes represent a very important group of water pollutants that appear in the effluents of different industries. These contaminants, by preventing the penetration of light, can have negative effects on the aquatic environment, causing... more
Dyes represent a very important group of water pollutants that appear in the effluents of different industries. These contaminants, by preventing the penetration of light, can have negative effects on the aquatic environment, causing problems to the ecosystem, and possibly being carcinogenic and genotoxic on human health. In particular tartrazine is a commonly not-biodegradable dye used in food industries and it, in high amount, could cause allergic and/or intolerance reactions. In the past decade only few effective photocatalysts for organic dye degradation under visible-light irradiation has been reported. Effective photocatalysts, such as ZnO, however, exhibit photodegradation activity only under ultraviolet irradiation. The coupling of ZnO, having a band gap of 3.2 eV, with low band gap photocatalysts could induce the removal of the dyes under visible light. So, in this work, LaFeO3, which has a band gap of about 2.1 eV, was supported on ZnO surface. The aim of this work was to ...
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This paper investigates the effect of controlled periodic illumination by visible LEDs on the performances of a visible-light-active N-doped TiO2 photocatalyst (N — TiO2) immobilized on glass spheres for wastewater treatment, using... more
This paper investigates the effect of controlled periodic illumination by visible LEDs on the performances of a visible-light-active N-doped TiO2 photocatalyst (N — TiO2) immobilized on glass spheres for wastewater treatment, using Methylene Blue (MB) dye as a model pollutant. Different LED dimming techniques are investigated and compared, including a classical Pulse Width Modulation (PWM) technique and a novel proposed Variable-Peak PWM technique. A modulation of dimming duty-cycle is adopted as well, which allows to control the light irradiation in a new way with respect to previously used methods. Experimental results highlight the improvement in MB photocatalytic degradation process obtained by using the proposed modulation techniques.
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We have synthesized different classes of monodispersed MFe2O4 (M=Fe, Co, Ni) nanoparticles by decomposition of metal-organic precursors in organic solvent and explored the reaction temperature effect on the nanoparticles average... more
We have synthesized different classes of monodispersed MFe2O4 (M=Fe, Co, Ni) nanoparticles by decomposition of metal-organic precursors in organic solvent and explored the reaction temperature effect on the nanoparticles average dimension. We obtained particle sizes in the range of 2-6 nm at different reaction temperatures. Moreover, we have tested some of these nanoparticles as patterned catalyst for CVD synthesis of carbon nanotubes on silicon wafer.
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Organic dyes in wastewater negatively affect aquatic life by impeding light penetration and they can eventually results in carcinogenic and genotoxic effects on human health. Tartrazine is a commonly not-biodegradable dye used in food... more
Organic dyes in wastewater negatively affect aquatic life by impeding light penetration and they can eventually results in carcinogenic and genotoxic effects on human health. Tartrazine is a commonly not-biodegradable dye used in food industries. The aim of this work was to evaluate the influence of operating conditions in the heterogeneous photo-Fenton process for the removal of tartrazine on structured catalysts. In particular LaFeO3 or Pt/LaFeO3 perovskite supported on honeycomb monoliths have been tested. The process efficiency was evaluated in terms of both dye discoloration and mineralization. The influence of initial dye concentration, H2O2 dosage, and initial pH of solution has been evaluated. Experimental results evidenced that the presence of the platinum allows the removal of the colour already in dark condition, enhancing the adsorption phase. Moreover, the highest photo-Fenton performances were obtained at natural solution pH (6), reaching the complete discoloration and...
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This work deals with the characterization of ZnS NanoParticles (NP), prepared by precipitation employing thioacetamide as sulfur source at different reaction time length. The attention is focused on the modification induced on structural,... more
This work deals with the characterization of ZnS NanoParticles (NP), prepared by precipitation employing thioacetamide as sulfur source at different reaction time length. The attention is focused on the modification induced on structural, surface and electronic properties of ZnS NP by post-synthesis treatments. These were aimed at removing from the samples surface adsorbed reactants, by washing or thermal treatments, both in air or vacuum. The effect of these parameters is followed by X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Fourier Transform InfraRed (FTIR), gas-volumetric and ThermoGravimetric Analysis (TGA). Moreover, the effect of nanostructuration on the semiconducting material band gap is evaluated by Diffuse Reflectance UV-Vis (DR UV-Vis) spectroscopy. Density Functional Theory (DFT) calculations have been employed to clarify the role of the adsorbed reactants on the surface stability and to assess the relationship between particle size and band gap va...
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The aim of this work is to study the photo-Fenton process for removing t-butyl methyl ether (MTBE) in wastewater by utilizing LaFeO
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In this work the photo-Fenton process for removing organic substances from wastewater was studied by utilizing LaFeO
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This study reports a novel approach to produce nitrogen doped magnetic core TiO2 nanoparticles (N- TiO2/FM). The treatment of wastewater streams by photocatalysis appears a feasible pre-treatment for many subsequent purification steps,... more
This study reports a novel approach to produce nitrogen doped magnetic core TiO2 nanoparticles (N- TiO2/FM). The treatment of wastewater streams by photocatalysis appears a feasible pre-treatment for many subsequent purification steps, such as membranes. In order to keep high efficiencies in dealing with the wastewater streams, the photocatalyst requires to be suspended in order to reach the water surface for proper irradiation and operation. A main drawback is the recovery of the suspended photocatalyst, that may be accomplished by magnetic filters (up to 99.9%) as soon as the titania nanoparticles are attached to magnetic nanocores (FM). Moreover, the photocatalyst should react to visible light and not only to UV (as pure titania), to operate with a high energy efficient process that may use LED lamps instead of UV lamps. This property can be acquired through nitrogen doping. Therefore, the production of NMTNP may represent a general solution to all these problems. The N-TiO2/FM w...
Research Interests: Chemical Engineering, Materials Science, Nanoparticle, Nanoparticles, Energy efficiency, and 15 moreDoping, Biodegradation, Photocatalysis, Spinning, Magnetism, Magnetic nanoparticles, Silica, Lighting, Nitrogen, Light Emitting Diodes, Irradiation, Purification, Frequency Modulation, Magnetic Nanoparticles, and Energy Efficiency
The impact of light modulation on the decolorization of Acid Orange 7 (AO7) in aqueous solution was examined in this paper. A fixed bed batch photocatalytic reactor with a flat plate geometry, irradiated by 240 white-light LEDs, was used.... more
The impact of light modulation on the decolorization of Acid Orange 7 (AO7) in aqueous solution was examined in this paper. A fixed bed batch photocatalytic reactor with a flat plate geometry, irradiated by 240 white-light LEDs, was used. A successful transfer of visible active photocatalyst (N-TiO2) in powder form on a polystyrene (PS) transparent plate was realized. The structured photocatalyst was characterized through SEM–EDX, Raman and UV-DRS analyses, evidencing the formation of a coating of N-TiO2 in the anatase phase, with a band-gap energy of 2.5 eV, and almost uniform distribution on the PS surface. Different LED dimming techniques, with fixed and variable duty-cycle values, were tested, and four types of light modulation were compared: fixed duty cycle (constant irradiation), sinusoidal variable duty cycle (sinusoidal variable irradiation), triangular variable duty cycle (triangular variable irradiation), and square wave variable duty cycle (square wave variable irradiati...
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Abstract This chapter starts with a brief introduction to the main polluting substances for air and water. Then, the attention is focused on the advanced oxidation processes and in particular to photocatalysis mediated by semiconductor... more
Abstract This chapter starts with a brief introduction to the main polluting substances for air and water. Then, the attention is focused on the advanced oxidation processes and in particular to photocatalysis mediated by semiconductor TiO2, underlining the advantages of this technology with respect to the traditional methods for the treatment of gaseous and water pollutants. Some key aspects of heterogeneous photocatalysis are described. Moreover, the chapter presents, more in detail, some examples related to the use of TiO2 in the photocatalytic removal of volatile organic compounds from gaseous stream, for photocatalytic indoor air purification and in the degradation of water pollutants.
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In this work, the optimization of Ni amount on LaFeO3 photocatalyst was studied in the photocatalytic molecular hydrogen production from glucose aqueous solution under UV light irradiation. LaFeO3 was synthesized via solution combustion... more
In this work, the optimization of Ni amount on LaFeO3 photocatalyst was studied in the photocatalytic molecular hydrogen production from glucose aqueous solution under UV light irradiation. LaFeO3 was synthesized via solution combustion synthesis and different amount of Ni were dispersed on LaFeO3 surface through deposition method in aqueous solution and using NaBH4 as reducing agent. The prepared samples were characterized with different techniques: Raman spectroscopy, UltraViolet-Visible Diffuse Reflectance Spettroscopy (UV–Vis-DRS), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), X-ray Fluorescence (XRF), Transmission Electron microscopy (TEM), and Scanning Electron microscopy (SEM) analyses. For all the investigated photocatalysts, the presence of Ni on perovskite surface resulted in a better activity compared to pure LaFeO3. In particular, it is possible to identify an optimal amount of Ni for which it is possible to obtain the best hydrogen production. Specifi...
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Aims: The aim of this work was to investigate the impact of light modulation parameters on the degradation of terephthalic acid, an organic model pollutant, within a heterogeneous photocatalytic system under visible light. For this... more
Aims: The aim of this work was to investigate the impact of light modulation parameters on the degradation of terephthalic acid, an organic model pollutant, within a heterogeneous photocatalytic system under visible light. For this purpose, a fixed bed photocatalytic reactor, irradiated by white-light LEDs matrix controlled by a system for light dimming, was used. The bed consisted of a nitrogen-doped titania photocatalyst deposited on polystyrene pellets. Background: Wastewater containing TPA can be treated into conventional aerobic biological units. However, the mineralization of TPA is slow and inefficient and its presence negatively influences the biodegradation efficiency because this pollutant inhibits microbial growth. Nowadays, innovative technologies named advanced oxidation processes (AOPs), such as heterogeneous photocatalysis with UV and visible light, ozonation, and Fenton oxidation, have gained popularity for effective organic destruction of TPA from wastewater. The he...
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ABSTRACT
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Mixing is a common process in food industry, and in particular it is interesting to develop optimal mixers in order maximize fluid mixing and minimize energy consumption by reducing the viscous dissipation effects. Although many studies... more
Mixing is a common process in food industry, and in particular it is interesting to develop optimal mixers in order maximize fluid mixing and minimize energy consumption by reducing the viscous dissipation effects. Although many studies and results had been presented in literature for both batch and static mixers (Rauline et al. 2000 and Mutsakis et al. 1986 for a review) the lack of a developed theory of instability for non-Newtonian fluids, quite common in the food industry, leaves the problem open. In this work, the Optimal Shape Design (OSD) technique was applied to design static mixers for a Newtonian (i.e., water) and pseudoplastic (i.e., peach puree) liquid. Results show for the Non-Newtonian case, a classical coaxial static mixer, the application of OSD allows a sensible improvement of the performances, while in the Newtonian case (High Efficiency Vortex mixer), due to the different design approach, the overall effects are negligible.