Search results for "Photocatalysis."
showing 10 items of 584 documents
Degradation of 4-nitrophenol (4-NP) using Fe–TiO2 as a heterogeneous photo-Fenton catalyst
2010
Photocatalytic degradation of 4-nitrophenol was investigated using Fe-doped (1, 3, 5 and 8 wt.% Fe) TiO(2) catalysts under UV light irradiation in aqueous dispersions in the presence of H(2)O(2). Photocatalysts with the lowest Fe content (1%) showed a considerably better behavior with respect to the unloaded TiO(2) and the catalysts with higher Fe contents. Photocatalytic degradation was studied under different conditions such as amounts of 1% Fe-TiO(2) catalyst, H(2)O(2) dose and initial pH of 4-NP solution. The results indicated that about 67.53% total organic carbon of a solution containing 20 mg L(-1) 4-NP was removed at pH 6.17 by using 4.9 mM of H(2)O(2) and 0.4 g L(-1) of the catalys…
Photocatalytic degradation of acid blue 80 in aqueous solutions containing TiO2 suspensions.
2001
The photocatalytic degradation of the anthraquinonic dye Acid Blue 80 in aqueous solutions containing TiO2 dispersions has been investigated. The process has been monitored by following either the disappearance of the dye (via HPLC) and the formation of its end-products (via IC, GC, and TOC analysis). Although a relatively fast decolorization of the solutions has been observed, the mineralization is slower, and the presence of residual organic compounds was evidenced even after long term irradiation, confirming the relevant stability of anthraquinone derivatives. The identification of various unstable intermedi ates formed after low irradiation times was performed by HPLC-MS, allowing us to…
Electron and Energy Transfer Mechanisms: The Double Nature of TiO2 Heterogeneous Photocatalysis
2021
Photocatalytic chemical transformations in the presence of irradiated TiO2 are generally considered in terms of interfacial electron transfer. However, more elusive energy-transfer-driven reactions have been also hypothesized to occur, mainly on the basis of the indirect evidence of detected reaction products whose existence could not be justified simply by electron transfer. Unlike in homogeneous and colloidal systems, where energy transfer mechanisms have been investigated deeply for several organic syntheses, understanding of similar processes in heterogeneous systems is at only a nascent level. However, this gap of knowledge can be filled by considering the important achievements of syn…
Titania Photocatalysts for Selective Oxidations in Water
2011
Heterogeneous photocatalysis by polycrystalline semiconductor oxides is an unconventional technology that has been mainly applied for the degradation of organic and inorganic pollutants in both the vapor and liquid phase. The application of photocatalysis in synthetic routes has also been researched in recent years, demonstrating its viability as an alternative route in organic chemistry. This work illustrates the main findings in the application of heterogeneous photocatalysis to the oxidation of organic compounds dissolved in water, free of any organic co-solvent. Two main aspects of the oxidative process have been studied: the first one is the partial oxidation of various mono-substitute…
Effect of Urea–Hydrogen Peroxide Content on the Photocatalytic Activity of Zinc Oxide Nanoparticles
2021
ZnO nanoparticles (NPs) were synthesized using zinc acetate dihydrate, ethanol, and oxalic acid as precursor, solvent, and complexing agent, respectively, and urea–hydrogen peroxide (UHP) as, simultaneously, nitrogen precursor and oxygen donor. The structural, morphological, textural, and optical properties of ZnO photocatalysts were investigated using different characterization methods such as XRD, SEM, BET, and UV-Vis-DRS. The XRD patterns showed that the products consisted of ZnO and revealed the presence of nitrogen. SEM images revealed the agglomeration and aggregation of NPs. The photocatalytic activity of ZnO samples was estimated based on the photo-oxidation of 2-propanol under UV i…
Visible light active self-cleaning materials based on porphyrin-sensitised titanium dioxide
2017
Starting from second half of last century, nanostructured semiconductors have had a crucial function in the material science because of their wide application field going from renewable energy to organic/hybrid electronics up to photocatalysis. Among those materials, titanium dioxide is probably the most used because of some important characteristics like the chemical/mechanical stability, environmental sustainability, its low cost and versatility. Indeed, it has been successfully employed as photo- and electro-active component in electronic devices as well as photocatalytic agent1 in water de-pollution application. Interestingly and importantly together, titanium dioxide may also be applie…
Photocatalysis: a promising route for 21st century organic chemistry
2007
One of the main goals of 21st century chemistry is to replace environmentally hazardous processes with energy efficient routes allowing to totally avoid the use and production of harmful chemicals and to maximise the quantity of raw material that ends up in the final product. Selective photocatalytic conversions will play a major role in this evolution and this account shows how photocatalysis is offering an alternative green route for the production of organics.
Genetic Algorithm Modeling for Photocatalytic Elimination of Impurity in Wastewater
2019
The existence of C.I. Acid Yellow 23 (AY23) in water causes a great danger to people and society. Here, we suggest an advanced technique which predicts the photochemical deletion of AY23. The genetic algorithm (GA) technique is suggested in order to predict the photocatalytic removal of AY23 by implementing the Ag-TiO\(_{2}\) nanoparticles provided under appropriate conditions.
Optical properties of TiO2 suspensions: Influence of pH and powder concentration on mean particle size
2007
WOS: 000250584100025
A reaction engineering approach to kinetic analysis of photocatalytic reactions in slurry systems
2016
Abstract The knowledge of the rate equation is fundamental for the assessment of the activity of the photocatalytic material and for the study, design and optimization of photocatalytic reactors. In the case of photocatalytic reactions, the local volumetric rate of photon absorption (LVRPA) affects the reaction rate and its inherently uneven distribution within a “slurry” reactor makes complex a correct kinetic analysis. In the present work it is shown which are the critical aspects of the kinetic analysis in slurry reactors and how to carry out photocatalytic experiments to minimize the misinterpretations of the experimental results. In particular, the influence of the type of illumination…