1,720,988 research outputs found
Greeen Synthesis of Bromine through photocatalysis and ozonation
No full textGreeen Synthesis of Bromine through photocatalysis and ozonatio
Br2 production from photocatalysis and/or ozonation of bromide containing aqueous solutions: kinetics and mechanisms
No full textBr2 production from photocatalysis and/or ozonation of bromide containing aqueous solutions: kinetics and mechanism
Comparison of the performances of an annular photocatalytic reactor with fluorescent lamp and a plane reactor with LEDs
No full textComparison of the performances of an annular photocatalytic reactor with fluorescent lamp and
a plane reactor with LED
Photocatalytic treatment with fixed-bed TiO2 catalyst of a PCB-contaminated effluent deriving from soya lecithin-assisted soil washing
No full textIntensification of Water Detoxification by Integrating Photocatalysis and Pervaporation
No full textMany studies have been made on the possibility of increasing the efficiency of the photocatalytic detoxification of water streams, since for several practical applications the need for increasing the yield of the process is important. In the present work, the integration of photocatalysis with a membrane separation process is studied in order to analyze the possibility of enhancing the efficiency. It is experimentally shown that for the integrated process, the rate of disappearance of a model pollutant (4-chlorophenol) is highly improved. Then it is demonstrated that this “process intensification” takes place through synergetic mechanisms that are identified, discussed, and optimized
Optimization of the thickness of a photocatalytic film on the basis of the effectiveness factor
No full textIn a supported ‘‘thick’’ photocatalytic film, internal diffusion of the reactant and transport of the photons might hinder the reactivity of the material and limit the obtainable rate of removal of the organic pollutant substrate. The effectiveness factor of the photocatalytic film is the index of the extent of the limitation.
Two dimensionless parameters affect the effectiveness factor: the optical thickness and the ratio, alpha, of the characteristic time of diffusion with respect to the characteristic time of reaction. The analysis demonstrates that the process is controlled by the diffusion of the substrate when the parameter alpha is high and it is controlled by the transport of the photons when the optical thickness is high.
It is also shown that different results are obtained if the film is illuminated from the fluid–film interface (PF) or from the glass–film interface (CF). In PF the observed rate of degradation increases with the film thickness, but no further enhancement of the rate of degradation is obtained when the thickness exceeds the depth where a substantial depletion of the photons or of the substrate takes place. In CF the rate of degradation reaches a maximum at an optimal thickness.
Finally, a new simple procedure to estimate the parameters and then to predict the best thickness is illustrated
A Rational Approach to the Design of Photocatalytic Reactors
No full textA model to assess the performances of an annular photocatalytic reactor has been developed by investigating different operational conditions through an analysis based on the proper dimensionless parameters (namely, the optical thickness, the Thiele modulus and two among the well-known Damkohler and Peclet numbers, which are properly redefined). Different dependences of the reaction kinetics on the local rate of radiant energy absorption are also considered. Because the progress of the reaction is affected by the radiation field, all these parameters are dependent on the catalyst concentration and then indirectly on the catalyst load. The conditions under which an optimal value for the catalyst concentration may exist are determined, thus contributing to provide insight to one aspect that is quite controversial in the literature
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
Pervaporation membrane reactors (Chapter 3)
Get PDFPervaporation is a peculiar membrane separation process which is now considered for the integration with some types of reactions in new promising and interesting applications. Indeed, pervaporation membrane reactors are suitable to some specific utilizations also in sustainable chemistry, which is an area currently characterized by a growing interest. The fundamentals of this type of membrane reactors are presented and the advantages and the difficulties in many applications are discussed and reviewed with particular attention to the opportunities for future developments
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