Search results for "photocatalytic"
showing 10 items of 91 documents
Selective photocatalytic oxidation of 5-hydroxymethyl-2-furfural in aqueous suspension of polymeric carbon nitride and its adduct with H2O2 in a sola…
2018
Abstract This work reports a study on the reactivity of polymeric carbon nitride (PCN) and PCN-H2O2 adduct samples for sunlight photocatalytic selective oxidation reactions. The characterization of these materials was reported in a previous paper where the reactivity towards the partial oxidation of 5-hydroxymethylfurfural (HMF) was studied by using two different laboratory scale photoreactors; one irradiated by UV lamps and the other one by natural sunlight. In the present study it has been confirmed the effectiveness of these C3N4 based materials for the selective partial oxidation of HMF to FDC (2,5-furandicarboxaldehyde) in aqueous medium in a pilot plant photoreactor irradiated by natu…
Recent Development on Self-Cleaning Cementitious Coatings
2013
The recent improvements in nano-technologies applied to building coatings are reported, starting from the historical origins of the research on photocatalysis. The description of the main air pollutants and the chemical mechanism of photocatalysis introduce to self-cleaning surfaces and the super-hydrophilic and hydrophobic attitude. Self-cleaning cementitious surfaces, due to nano-structured photocatalysts, mainly titanium dioxide, show environmental benefit in reduction of air pollutants and many experimental evidences are reported together with several applications on building construction. International standards and main spectroscopic techniques aim to evaluate the benefit in terms of …
Photocatalytic and Catalytic Reactions in Gas–Solid and in Liquid–Solid Systems
2019
Abstract Heterogeneous photocatalytic and thermal-catalytic reactions are here presented focusing the differences and similarities between the two processes. When possible, the comparison was made for the same chemical reaction in the presence of an inorganic material playing the role of both catalyst or/and photocatalyst. Several examples are presented where a catalytic reaction can occur at milder experimental conditions and, particularly, at lower temperature when the system is also irradiated by UV and/or visible light. The differences in mechanistic aspects, conversions, and selectivities between catalytic and photocatalytic reactions will be also considered because these occurrences a…
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…
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…
The effects of a saline environment on the durability of commercial photocatalytic paints
2016
The use of photocatalytic products for surface coating of buildings ensures the reduction of certain air pollutants and greater duration of color over time, due to the reduced attitude of air particulate to adhere to the treated surfaces. The world market is producing a wide range of coatings, transparent and opaque, high initial performance, but there is a lack of data on their durability. The knowledge of performance over time of these new products is at the basis of the Regulation (EU) no. 305/2011, which repealed Council Directive 89/106/EEC and introduced the seventh requirement regarding the sustainability and particularly durability of construction works. This study focuses on the as…
Photocatalytic ozonation under visible light for the remediation of water effluents and its integration with an electro-membrane bioreactor
2018
Abstract Photocatalysis and photocatalytic ozonation under visible light have been applied for the purification of a complex aqueous matrix such as the grey water of Masdar City (UAE), by using N-doped brookite-rutile catalysts. Preliminary runs on 4-nitrophenol (4-NP) solutions allowed to test the reaction system in the presence of a model pollutant and to afford the relevant kinetic parameters of the process. Subsequently, the remediation of grey water effluent has been evaluated in terms of the reduction of total organic carbon (TOC) and bacterial counts. The concentration of the most abundant inorganic ionic species in the effluent has been also monitored during reaction. Photocatalytic…
Photocatalytic activity of TiO2/SiO2 systems
2009
Silica-supported TiO(2) powders were synthesized by a wet method under mild conditions. The aim of the work was the preparation of TiO(2)/SiO(2) additives for photocatalytic cements. Three types of commercial SiO(2) were used as supports: Cabot, Axim and Fly Ash. Cabot silica was ultra-pure whereas the other two silica contained different percentages of various oxides. The TiO(2)/SiO(2) samples, denoted TiO(2)/Cabot, TiO(2)/Axim and TiO(2)/Fly Ash, were prepared by boiling suspensions obtained by addition of silica to a solution of TiCl(4) in water (volume ratio 1:10). The photocatalytic activity was evaluated in a gas-solid system both in batch and in continuous reactors using 2-propanol a…
Modeling of a continuous photocatalytic reactor for isovaleraldehyde oxidation: Effect of different operating parameters and chemical degradation pat…
2013
International audience; An investigation of isovaleraldehyde (ISOV) photocatalytic oxidation was conducted at initial concentrations ranging from 25 to 150 mg/m3 and different relative humidities (5-90% RH) in order to characterize the process performances close to indoor air conditions. Experiments were carried out in two different reactors: cylinder and flat-plate photoreactor (planar reactor) at different air gap (20-60 mm) and gas residence times (0.67-5.0 s). A plug flow reactor system was developed in order to perform kinetic studies of (i) isovaleraldehyde removal, (ii) selectivity of CO2, (iii) byproducts formation and removal. It appears that ISOV removal efficiencies increased wit…