Examinando por Autor "Martin Somer, Miguel"

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Influence of light distribution on the performance of photocatalytic reactors: LED vs mercury lamps.
(Elsevier, 2017-10-15) Martin Somer, Miguel
UV LED technology has revolutionized the photocatalytic processes due to their significant advantages over traditional mercury-based illumination sources, specifically its higher energy efficiency. However, the use of LED also introduces important changes in the light distribution achieved inside a photocatalytic reactor that has to be considered. In this study an exhaustive comparison of three different UV-A sources (a mercury fluorescent lamp, a 8-LED based system and a 40-LED based system) with different light distribution has been carried out. Theoretical distribution of the light was modeled in Ansys Fluent v14.5. The results of photocatalytic activity for methanol oxidation show that a homogeneous light distribution allows achieving a higher photonic efficiency. The diffuse and uniform emission of the fluorescent mercury lamp partially compensates its lower energy efficiency, leading to similar results than the 8-LED system. This fact can be explained taking in consideration that electron-hole recombination is enhanced in the areas with higher radiation intensities, decreasing the overall efficiency. In the case of the 40 LED due to the improvement of the light homogeneity and energy efficiency, higher reaction rates per kWh were achieved. These results show that despite the advantages of LED, if light distribution is not optimized it can result in lighting systems less effective than traditional ones. On the opposite, for bacterial inactivation the results show that there is no clear difference when using different lighting sources. The existence of a highly non-uniform radiation field with regions of the reactor with very high intensities seems to enhance the efficiency of the direct bacterial inactivation when LED are used, compensating the decrease in the charge transfer efficiency of the semiconductor based photocatalytic process.
Modelling photochemical processes for water disinfection
(Royal Society of Chemistry, 2022-12-21) Casado, Cintia; García, Ángela; Martin Somer, Miguel; Moreno, José; Marugán, Javier
Photochemical processes cover a wide range of technologies for drinking-water and wastewater disinfection, including UV-C, UV/H2O2, photo-Fenton, heterogeneous photocatalysis, solar disinfection, etc. They share the absorption of photons as the activation step triggering the global process. However, significant differences appear depending on the specific technology, including the required wavelength, light sources, reactor design and optimal operational conditions. This chapter focuses on the modelling strategies for the simulation and design of photochemical processes for water treatment, with particular emphasis on the use of sunlight and LED light sources. The necessity of a mechanistic description of the kinetics of the process and its explicit coupling with radiation transport in the system is shown as the best approach for the rigorous design of photochemical reactors. Application of computational fluid-dynamics techniques is also described as a way for the optimal simulation of these multiphysics processes.
Multitarget evaluation of the photocatalytic activity of P25-SiO2 prepared by atomic layer deposition.
(MDPI, 2020-04-22) Martin Somer, Miguel; Benz, Dominik; van Ommen, Ruud; Marugan, Javier
This work presents the evaluation of the photocatalytic activity of P25 TiO2 particles, coated with SiO2, using atomic layer deposition (ALD) for the photocatalytic removal of methylene blue, oxidation of methanol and inactivation of Escherichia coli bacteria in water and its comparative evaluation with bare P25 TiO2. Two different reactor configurations were used, a slurry reactor with the catalyst in suspension, and a structured reactor with the catalyst immobilized in macroporous foams, that enables the long-term operation of the process in continuous mode, without the necessity of separation of the particles. The results show that the incorporation of SiO2 decreases the efficiency of the photocatalytic oxidation of methanol, whereas a significant improvement in the removal of methylene blue is achieved, and no significant changes are observed in the photocatalytic inactivation of bacteria. Adsorption tests showed that the improvements, observed in the removal of methylene blue by the incorporation of SiO2, was mainly due to an increase in its adsorption. The improvement in the adsorption step as part of the global photocatalytic process led to a significant increase in its removal efficiency. Similar conclusions were reached for bacterial inactivation where the loss of photocatalytic efficiency, suggested by the methanol oxidation tests, was counteracted with a better adherence of bacteria to the catalyst that improved its elimination. With respect to the use of macroporous foams as support, a reduction in the photocatalytic efficiency is observed, as expected from the decrease in the available surface area. Nevertheless, this lower efficiency can be counteracted by the operational improvement derived from the easy catalyst reuse.
Treatment of Wastewaters from a Personal Care Products Factory by Advanced Biological Systems
(Taylor and Francis, 2015-06-22) Monsalvo, Victor; Lopez, Jesus; Martin Somer, Miguel; Fernandez Mohedano, Angel; Rodriguez, Juan José
Efficient Management of Wastewater from Manufacturing is an accessible research compendium, highly useful for anyone involved with the phytosanitaries, food and beverage, pharmaceutical, or textile industries. The editor, Victor Monsalvo, is a well-respected expert in the field who has included many of his own studies. He has also enlisted articles