614 research outputs found
Il colore blu degli spinelli a cobalto: distribuzione cationica e assorbimento UV-VIS-NIR in cristalli (Mg,Co)Al2O4 di sintesi
No full text40A) D'Ippolito V., Andreozzi G.B. (2010). Il colore blu negli spinelli a cobalto: distribuzione cationica e assorbimento UV-VIS-NIR in cristalli di (Mg,Co)Al2O4 di sintesi. Rivista Gemmologica Italiana, 5, 120-123
Nanostructured catalysts production through electrochemical methods: synthesis, characterization and possible applications
No full textIn this work a study of the electrochemical synthesis of TiO2 based nanostructured electrodes for photocatalytic and electrocatalytic applications is presented.
The study on the electrochemical synthesis of TiO2 nanotubes (NTs) through anodization has been aimed to develop a novel “single-step” anodization method in symmetric electrochemical cells (i.e. both electrodes are Ti sheets), instead of traditional “double-step” processes, which include the sequence of two anodizations separated by the dissolution of the first formed TiO2 and are carried out in asymmetric cells with Pt electrocatalysts as counter electrodes.
Besides the anodization, in relation to the specific applications discussed in this study, further electrochemical synthesis routes, employing the anodized TiO2 electrodes, were investigated.
In photocatalytic applications, the electrodeposition of Cu2O nanoparticles over the surface of TiO2 NTs has been adopted as strategy to overcome the limited light absorption of the bare TiO2 photocatalyst (active only under UV irradiation). Here, in agreement with most of the studies among the available literature, under visible irradiation the TiO2/Cu2O based electrodes showed improved performances than the bare TiO2 (inactive under only visible light). These improved performances have been frequently claimed based on the only analysis of the photocatalytic performances under visible light, while in the present study it was found that, when the light source employed was UV + visible rather than only visible, the photo-catalytic performances of the composite electrodes were lower as compared to the bare TiO2 electrode. Furthermore, the bare TiO2 activity registered under UV + visible was higher than the composite electrode activity registered under only visible irradiation. To overcome this unexpected behaviour, at this stage the study has been aimed to the development of photo/electrochemical post-treatments, which allowed to improve the performances of the Cu2O based electrodes also under UV + visible light.
Black TiO2 electrocatalysts were finally synthesized in the framework of the activities related to the e.THROUGH EU project (H2020-MSCA-RISE-2017-778045), which is aimed to the recovery of critical raw materials and sustainable remediation.
Briefly, this goal would be achieved through the development of electrokinetic technologies for soil remediation, as in the case of the electrodialytic mine tailings remediation performed in this work. Electrodialytic remediation is generally carried out in symmetric cells which employ commercial Ti/MMO (Mixed Metal Oxides; Ir/Ru-based) electrodes, for both anode and cathode. Main limit for the real employment of these technologies are the energy costs related to the stirring and the power supply. Here, considering that the main reactions involved during the process are the water splitting reactions, one of the strategies to minimize the overall process cost is based on the recovery of the produced hydrogen. Considering that Ir-/Ru- based compounds are benchmark catalysts for the anodic reaction involved rather than the cathodic hydrogen evolution reaction, at this stage, the study has been aimed to the development of a non-commercial hydrogen evolution reaction (HER) electrocatalyst, namely the Black TiO2 based electrodes. These electrodes have been synthesized through the electrochemical reduction of the Ti/TiO2 electrodes resulting from the anodization, employing Ti sheets as counter electrodes
Oxidation of benzothiazole,2-mercaptobenzothiazole and 2-hydroxybenzothiazole in aqueous solution by means of H2O2/UV or photoassisted Fenton systems
No full textKinetic modeling of pyruvic acid ozonation in aqueous solution catalyzed by MnII and Mn IV ions
No full textPhotovoltaic waste as source of valuable materials: A new recovery mechanical approach
No full textEnd-of-life photovoltaic modules are hazardous waste belonging to the category of waste from electrical and electronic equipment. They contain environmentally hazardous substances, poorly biodegradable materials but also valuable materials. The recovery of these last is the main goal of PV-waste treatments. In order to facilitate the recovery and produce released fractions that are suitable for the recycling of glass, Silicon, Silver, Copper, Lead and Aluminium, the mechanical technics applied in the management of all e-waste without differentiation by type, are the most commonly used. However, a new and appropriate management strategy is required to maximize the recovery efficiency and improve the quality of recovered materials. This paper aims to identify and overcome the critical points in the PV-waste management mechanical processes and provides information on more efficient routes for their treatment. It aims to shed some light on the usefulness of adopting a specific and dedicated approach, to optimize the recovery rate and recovered materials purity level to send to recycling. A new mechanical process of separation and recovery of materials is proposed and compared with a typical conventional e-waste treatment process. The developed process makes improvements in the materials separation step, initial stage conditioning the process, making it more efficient than the conventional one
“Oxidation of benzothiazole, 2-mercaptobenzothiazole and 2-hydroxybenzothiazole in aqueous solution by means of H2O2/UV or photoassisted Fenton systems”.
No full textNumerical analysis of radiation effects in a metallic foam by means of the radiative conductivity model
No full textThe aim of this work is the evaluation of the radiation contribution to the steady-state heat transfer in
metallic foams by means of the radiative conductivity model. Because of the complexity of the structure,
reference is made to a simplified physical radiative model, where the elementary cell of the foams is
treated as a cubic cell. The contribution of the radiation heat transfer is investigated on a local basis. The
local radiative conductivity has been used to evaluate the influence of radiative heat transfer in a two
dimensional conductive-convective-radiative problem involving a forced fluid flow within a heated
channel filled with a metallic foam. The effect of the solid emissivity and the foam porosity is pointed out
for different foams
Thermal and fluid dynamic behavior of a horizontal channel with adiabatic moving lower plate
No full textRadiative Effects on Mixed Convection in a Uniformly Heated Vertical Convergent Channel with an Unheated Moving Plate
No full textFluids engineering is extremely important in a wide variety of materials processing systems, such as soldering, welding, extrusion of plastics and other polymeric materials, Chemical Vapor Deposition (CVD), composite materials manufacturing. In particular, mixed convection due to moving surfaces is very important in these applications. Mixed convection in a channel, as a result of buoyancy and motion of one of its walls has received little research attention and few guidelines are available for choosing the best performing channel configuration, particularly when radiative effects are significant. In this study a numerical investigation of the effect of radiation on mixed convection in air due to the interaction between a buoyancy flow and an unheated moving plate induced flow in a uniformly heated convergent vertical channel is carried out. The moving plate has a constant velocity and moves in the buoyancy force direction. The principal walls of the channel are heated at uniform heat flux. The numerical analysis is accomplished by means of the commercial code Fluent. The effects of the wall emissivity, the minimum channel spacing, the converging angle and the moving plate velocity are investigated and results in terms of air velocity and temperature fields inside the channel and wall temperature profiles, both of the moving and the heated plates, are given. Nusselt numbers, both accounting and not for the radiative contribution to heat removal, are also presented
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