Search results for "Photocatalysis."
showing 10 items of 584 documents
Visible-light driven oxidation of gaseous aliphatic alcohols to the corresponding carbonyls via TiO2 sensitized by a perylene derivative
2013
Sensitized P25 TiO2 was prepared by wet impregnation with a home-prepared perylene dye, i.e., N,N?-bis(2-(1- piperazino)ethyl)-3,4,9,10-perylene-tetracarboxylic acid diimide dichloride (PZPER). Energy levels of PZPER were found to be compatible with those of TiO2 allowing fast electron transfer. The obtained catalyst has been characterized and used in the gas-phase partial oxidation of aliphatic primary and secondary alcohols, i.e., methanol, ethanol, and 2- propanol. The reaction was carried out under cut-off (?> 400 nm) simulated solar radiation in O2 atmosphere. The perylene derivative allowed a good absorbance of visible radiation thanks to its low optical energy gap (2.6 eV) which was …
Isovaleraldehyde degradation using UV photocatalytic and dielectric barrier discharge reactors, and their combinations
2015
International audience; The abatement of isovaleraldehyde present in air was carried out in UV photocatalytic and dielectric barrier discharge reactors (and their combinations) for concentrations up to 150 mg C m−3 and air flow rates ranging from 4 to 10 m3 h−1. A kinetic study was performed following a Langmuir–Hinshelwood model. Photocatalytic treatment of an isovaleraldehyde and isovaleric acid mixture showed a clear inhibition of isovaleric acid abatement in presence of isovaleraldehyde. Dielectric barrier discharge treatment of isovaleraldehyde showed an increase of removal efficiency with applied voltage and a decrease with air flow rate and inlet concentration. Moreover, introduction…
Study on a photocatalytic membrane reactor for water purification
2000
Abstract Some results obtained in a photocatalytic membrane reactor, to be used for degradation of toxic organic species dissolved in water, are reported. The catalyst, TiO 2 P25 Degussa, was immobilised by means of a flat sheet polymeric membrane and 4-Nitrophenol (4-NP) was used as a model molecule to evaluate the reactor performance. A preliminary investigation of the stability, under UV irradiation, of some eligible polymeric membranes was carried out by using scanning electron microscopy (SEM), optical microscopy (OM), determinations of water permeation flux (WPF) and total organic carbon (TOC). These tests showed that commercial membranes made of fluoride + PP (FS 50 PP-Dow), polysulp…
CO2 conversion in a photocatalytic continuous membrane reactor
2016
The reduction of CO2 with water by using photocatalysts is one of the most promising new methods for achieving CO2 conversion to valuable hydrocarbons such as methanol (MeOH). In this work, prepared TiO2-Nafion (TM)-based membranes were used in a photocatalytic membrane reactor, operated in continuous mode, for converting CO2 to methanol. By using the membrane with the best TiO2 distribution, a MeOH flow rate/TiO2 weight of 45 mu mol (g(catalyst) h)(-1) was measured when operating at 2 bar of feed pressure. This value is higher than those reported in most of the literature data to date. Moreover, methanol production is considered as a relevant advance over the existing literature results wh…
Microwave-assisted chemical modification of g-C3N4 for photoinduced processes: organic degradation, hydrogen production and selective oxidation of al…
2023
g-C3N4 powders were treated by means of the microwave technique in three different aqueous and organic media (HNO3, NaOH and N,N-dimethylformamide). All powders were analyzed by XRD reveling that g-C3N4 maintains its structure. The morphology of the samples was analyzed with scanning electron microscopy, where the micrographs reveals that the modifcation occurs on the surface of the g-C3N4. The photocatalytic activity of the samples was evaluated in the degradation of ciprofoxacin, hydrogen production and for the selective partial oxidation of 4-methoxybenzylalcohol (4-MBA) to its aldehyde. The sample treated with HNO3 (C3N4-HNO3) shows the best photocatalytic performance in the degradation…
Genotoxicity of citrus wastewater in prokaryotic and eukaryotic cells and efficiency of heterogeneous photocatalysis by TiO(2).
2012
Abstract The presence of (±)α-pinene, (+)β-pinene, (+)3-carene, and R-(+)limonene terpenes in wastewater of a citrus transformation factory was detected and analyzed, in a previous study, by using Solid Phase Micro-extraction (SPME) followed by GC analyses. Purpose of that research was to compare the genotoxic responses of mixtures of terpenes with the genotoxicity of the individual compounds, and the biological effects of actual wastewater. Genotoxicity was evaluated in the Salmonella reversion assay (Ames test) and in V79 cells by Comet assay. Ames tests indicated that the four single terpenes did not induce an increase of revertants frequency. On the contrary, the mixtures of terpenes ca…
Photocatalytic coalescence of functionalized gold nanoparticles.
2009
A novel strategy for the synthesis of chromophore-functionalized AuNPs with a narrow size distribution is reported. It consists of increasing the size of preprepared NPs by means of a fast (second scale) and clean (light and an organic photocatalyst) method. The results agree with thiolate ligand liberation from the NP surface promoted by photogenerated radicals. This lets gold cores come together and finally coalesce.
A simple method to fabricate high-performance nanostructured WO3 photocatalysts with adjusted morphology in the presence of complexing agents
2017
[EN] The rich and complex chemistry of tungsten was employed to synthesize innovative WO3 nanoplatelets/nanosheets by simple anodization in acidic electrolytes containing different concentrations of complexing agents or ligands, namely F- and H2O2. The morphological and photoelectrochemical properties of these nanostructures were characterized. The best of these nanostructures generated stable photocurrent densities of ca. 1.8 mA cm(-2) at relatively low bias potentials (for WO3) of 0.7 V-Ag/AgCl under simulated solar irradiation, which can be attributed to a very high active surface area. This work demonstrates that the morphology and dimensions of these nanostructures, as well as their ph…
Recent Advances in Photocatalytic Functionalization of Quinoxalin‐2‐ones
2020
Quinoxalin‐2(1H)‐one is an important class of nitrogen heterocycle in medicinal and pharmaceutical industry, which became a synthetic target in organic chemistry in recent years. This review covers the recent advances in the functionalization of this particular nitrogen heterocycle through photocatalysis.
Two-Dimensional Modeling of a Flat-Plate Photocatalytic Reactor for Oxidation of Indoor Air Pollutants
2007
In this paper we present a two-dimensional (2-D) analysis of a narrow-slit, flat-plate, single-pass, flow-through photocatalytic reactor for air purification. The continuity equation for convection and diffusion in two dimensions, under un-steady-state conditions, was coupled with radiation field modeling and photocatalytic reaction kinetics to model the transient and steady-state behavior of the reactor. The model was applied to the photocatalytic oxidation of trichloroethylene (TCE) in humidified air streams under different experimental conditions. The kinetic parameters determined by a three-dimensional (3-D) computational fluid dynamics model of the reactor were used in the 2-D model si…