1,721,101 research outputs found
Photoelectrocatalytic reactors and light sources
No full textPhotoelectrocatalysis (PEC) couples electrochemical methods with photocatalysis (PC) to enhance the separation of the photoproduced electron and hole pairs at semiconductor active surface, thus increasing the photocatalytic efficiency. PEC technology is considered one of the most promising method for processes as water treatment, fuel generation, and PEC sensing. This chapter try to link fundamental research and practical applications in photoelectrochemical engineering including reactors design strategies in different scales
Photocatalytic oxidation of nitrobenzene and phenylamine: pathways and kinetics
No full textThe oxidation of nitrobenzene and phenylamine has been carried out by heterogeneous photocatalysis in aqueous suspensions of commercial TiO2. The photoreactivity results indicate that two reaction pathways occur in parallel with both substrates from the start of irradiation: partial oxidation to monohydroxy derivatives and mineralization. The first pathway involves the entering of radical HO• into the aromatic ring giving rise to monohydroxy derivatives, and the second one involves the total oxidation of the substrates to CO2. The partial oxidation of nitrobenzene produces all the three possible monohydroxy derivatives, while that of phenylamine only produces the ortho‐ and para‐isomers. The extent of adsorption in the dark was found to be about 8% mol for nitrobenzene, while the amounts were not detectable for phenylamine. The Langmuir‐Hinshelwood approach has been satisfactorily applied for modeling the photoreactivity results, and the values of the kinetic model parameters have been determined
Preface to the special issue entitled “New frontiers in photo(thermo)catalysis” in honour of Prof. Leonardo Palmisano
No full textThis Special issue of Catalysis Today entitled “New frontiers in photo(thermo)catalysis” is dedicated to the retirement and to the career of the colleague and friend Prof. Leonardo Palmisano who devoted his life to Science and student
Selective photocatalytic and photoelectrocatalytic synthesis of valuable compounds in aqueous medium
Get PDFIn the past decades, photocatalytic and photoelectrocatalytic methods have been widely employed for the degradation of harmful compounds present both is gaseous and aqueous effluents. In the last years scientists have paid great attention to the synthesis of valuable compounds and hydrogen production. Organic syntheses are generally carried out in organic solvents, under high temperature/pressure, with toxic oxidants such as permanganate. On the other hand, photocatalysis and photoelectrocatalysis using water as solvent, air or water as oxidant, and sunlight as energy source, can be an efficient alternative to the traditional, non-environmentally friendly methods. This review summarizes the photocatalytic and photoelectrocatalytic transformations of organic molecules to commercially valuable products in water, sometimes evaluating also the contemporary H2 production. The reaction conditions, mechanisms and kinetics are presented and discussed. Future perspectives are also given
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Photocatalytic ozonation: Maximization of the reaction rate and control of undesired by-products
Get PDFIn the so-called photocatalytic ozonation (PO) synergistic effects between photocatalysis and ozonation enhance the rate of oxidation of organic compounds, therefore this integrated process is very promising for use in water treatment. In the present work, it is demonstrated that the improvement that can be obtained by the integrated process in comparison with the uncoupled processes depends on the relative weight between photocatalysis and ozonation. In this respect, it has been found that a relatively low rate of photocatalysis (0.3 times the rate of ozonation) is sufficient to get the highest synergy and to maximize the performances in the oxidation of formate, the adopted model organic compound. The benefits of the coupling of photocatalysis to ozonation are not limited to the increase of the oxidation rate, but include also the control of the ozonation by-product of main concern (bromate). The effect of the pH, of the presence of oxidizable organic compounds, of the presence of nitrogen on the formation or on the reduction of bromate are experimentally studied and discussed. The obtained results have relevance for the practical applications of PO, since on these bases it is possible to identify proper operating conditions
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