Investigación

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Browsing Investigación by Author "Alfonsín, Víctor"

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    Assessment of Selected Alternative Fuels for Spanish Navy Ships According to Multi-Criteria Decision Analysis
    (Journal of Marine Science and Engineering, 2023-12) Álvarez-Feijoo, Miguel A.; Alfonsín, Víctor; Álvarez-Feijoo, Miguel A.; Llopis, Lara
    Climate change and environmental degradation are growing concerns in today’s society, which has led to greater awareness and responsibility regarding the need to adopt sustainable practices. The European Union has established the goal of achieving climate neutrality by 2050, which implies a significant reduction in greenhouse gas emissions in all sectors. To achieve this goal, renewable energies, the circular economy, and energy efficiency are being promoted. A major source of emissions is the use of fossil fuels in different types of ships (from transport ships to those used by national navies). Among these, it highlights the growing interest of the defense sector in trying to reduce these emissions. The Spanish Ministry of Defense is also involved in this effort and is taking steps to reduce the carbon footprint in military operations and improve sustainability in equipment acquisition and maintenance. The objective of this study is to identify the most promising alternative fuel among those under development for possible implementation on Spanish Navy ships in order to reduce greenhouse gas emissions and improve its capabilities. To achieve this, a multi-criteria decision-making method will be used to determine the most viable fuel option. The data provided by the officers of the Spanish Navy is of great importance, thanks to their long careers in front of the ships. The analysis revealed that hydrogen was the most suitable fuel with the highest priority, ahead of LNG, and scored the highest in most of the sections of the officials’ ratings. These fuels are less polluting and would allow a significant reduction in emissions during the navigation of ships. However, a further study would also have to be carried out on the costs of adapting to their use and the safety of their use.
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    Biochar Amendments and Phytoremediation: A Combined Approach for Effective Lead Removal in Shooting Range Soils
    (Toxics, 2024) Maceiras, Rocío; Pérez-Rial, Leticia; Alfonsín, Víctor; Feijoo, Jorge; López, Ignacio
    The increasing contamination of soil with heavy metals poses a problem to environmental sustainability. Among these pollutants, lead is particularly concerning due to its persistence in the environment, with harmful effects on human health and ecosystems. Various strategies that combine phytoremediation techniques with soil amendments have emerged to mitigate lead contamination. In this context, biochar has gained significant attention for its potential to enhance soil quality and remediate metal-contaminated environments. This study aims to investigate the combined effect of biochar amendments on the phytoremediation of lead-contaminated shooting range soils. A series of experiments were conducted to determine the impact of the amount and distribution of biochar on lead removal from soil. Soil samples were incubated with biochar for one week, after which two types of seeds (Brassica rapa and Lolium perenne) were planted. Plant and root lengths, as well as the number of germinated seeds, were measured, and a statistical analysis was conducted to determine the influence of the amendments. After one month, the Pb concentration decreased by more than 70%. Our results demonstrate that seed germination and plant growth were significantly better in soil samples where biochar was mixed rather than applied superficially, with the optimal performance observed at a 10% wt. biochar amendment. Additionally, the combined use of biochar and phytoremediation proved highly effective in immobilizing lead and reducing its bioavailability. These findings suggest that the combination of biochar, particularly when mixed at appropriate concentrations, and Brassica rapa significantly improved lead removal efficiency.
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    Bioethanol production from industrial algae waste
    (Waste management, 2019) Alfonsín, Víctor; Maceiras, Rocío; Gutiérrez, Carlos
    This paper presents a study carried out to determine the feasibility to obtain bioethanol from an industrial algae waste. The influence of some parameters on acid hydrolysis was studied. The results indicated that the overall hydrolysis ability is a function of the combined action of acid concentration, temperature and reaction time. The hydrolysates with higher amount of reducing sugars were used for ethanolic fermentation using S. Cerevisiae. The highest bioethanol yield 11.6 gEtOH/galgae was obtained at 70 min, a sulphuric acid concentration of 9% wt. and acid/dried algae ratio of 7. The present study showed that the industrial waste of Euchema Spinosum contains carbohydrates that can be converted into bioethanol with an efficiency of 75%. Moreover, the potential of the residue after acid hydrolysis process as sustainable solid fuel regarding its properties was analysed. The results were compared with those obtained from the literature and discussed according to international standards.
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    C02 Capture via Adsorption Using Silica Gel
    (European Journal of Sustainable Development, 2024-10-01) Pérez-Rial, Leticia; Alfonsín, Víctor; Maceiras, Rocío; Feijoo, Jorge; Vallejo, Javier P.
    This paper investigates the potential of silica gel as an effective adsorbent for C02 capture. The study explores the adsorption mechanisms, the efficiency of C02 upta.ke, and sorne factors influencing the adsorption capacity of silica gel.The experimental results demonstrate the significant potential of silica gel for C02 adsorption under various conditions. Toe adsorption capacity was found to be highly dependent on parameters such as gas flow rate and the particle size of silica gel. The findings suggest that ,vith optimized conditions, silica gel could be a viable material for reducing atmospheric C02 levels. This research contributes to the development of sustainable and efficient technologies for mitigating climate change through carbon dioxide capture and storage.
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    CO2 Capture via Adsorption Using Silica Gel
    (European Journal of Sustainable Development, 2024) Pérez-Rial, Leticia; Alfonsín, Víctor; Maceiras, Rocío; Feijoo, Jorge; Vallejo, Javier P.
    This paper investigates the potential of silica gel as an effective adsorbent for CO2 capture. The study explores the adsorption mechanisms, the efficiency of CO2 uptake, and some factors influencing the adsorption capacity of silica gel. The experimental results demonstrate the significant potential of silica gel for CO2 adsorption under various conditions. The adsorption capacity was found to be highly dependent on parameters such as gas flow rate and the particle size of silica gel. The findings suggest that with optimized conditions, silica gel could be a viable material for reducing atmospheric CO2 levels. This research contributes to the development of sustainable and efficient technologies for mitigating climate change through carbon dioxide capture and storage.
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    Influence of alumina fixed-bed in steam reforming of glycerol for hydrogen production (7th International Conference on Renewable Energy and Conservation, ICREC 2022 November 18–20, 2022, Paris, France)
    (Energy Reports, 2023) Maceiras, Rocío; Feijoo, Jorge; Alfonsín, Víctor; Pérez-Rial, Leticia; Álvarez-Feijoo, Miguel A.; Falcón, Pablo; Vallejo, Javier P.
    In this study, hydrogen production by steam reforming was carried out in a tubular fixed-bed reactor. The influence of some operating variables such as temperature, flow rate of the feeding glycerol solution and space velocity on hydrogen production under a non-catalyzed reaction was analyzed. The results showed that the hydrogen yield increased with temperature and decreased with the space velocity. As the feedstock flow rate increased, the hydrogen yield decreased rapidly. Compared with a reference experiment without fixed-bed, the use of non-porous alumina fixed-bed showed better results. Under the best reaction conditions (900 ◦C and a feedstock flow rate of 0.85 g/min), 17 L/h of syngas were obtained, with a purity of about 55% of hydrogen and a production of 2.7 moles of hydrogen by mol of glycerol.
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    Microwave Assisted Alkaline Pretreatment of AlgaeWaste in the Production of Cellulosic Bioethanol
    (Energies, 2021, 14, 5891, 2021) Maceiras, Rocío; Alfonsín, Víctor; Seguí, Luis; González, Juan F.
    Biomass pretreatment has an important role in the production of cellulosic bioethanol. In this study, the effectiveness of microwave assisted alkaline pretreatment of algae waste was analysed. After pretreatment, the product was hydrolysed using sulphuric acid. The effects of microwave power, irradiating time, solid–liquid ratio and NaOH concentration were examined. Under the best conditions, the fermentable sugars were converted to cellulosic bioethanol using Saccharomyces Cerevisiae with a bioethanol yield of 1.93 0.01 g/g and a fermentation efficiency of 40.4%. The reducing sugars concentration was 30% higher than that obtained from conventional hydrolysis without pretreatment. The obtained results suggest that microwave assisted alkaline pretreatment is effective in improving the production of cellulosic bioethanol of algae waste compared to that without microwave effect. Considering energy consumption, low microwave power and short microwave irradiation time are favourable for this pretreatment.
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    Study of natural zeolites for hydrogen purification: CO2 adsorption capacity and kinetic mechanism
    (Fuel, 2024-11-15) Maceiras, Rocío; Falcón, Pablo; Alfonsín, Víctor; Pérez-Rial, Leticia; Feijoo, Jorge
    Hydrogen is considered a promising alternative fuel. However, in order to be used, it is necessary to achieve a high degree of purity through purification processes. Adsorption is considered one of the most important techniques for purification. In this research, the CO2 adsorption capacity and kinetic mechanism of natural zeolite were investigated with the aim to understand the carbon dioxide adsorption behaviour under different operating conditions. Multicomponent breakthrough curves of a mixture of H2/CO/CH4/CO2 were obtained at different pressures and gas flow rates. Moreover, the analysis of CO2 adsorption equilibrium and kinetics were carried out. The obtained adsorption isotherm data were fitted with different model equations. Freundlich, Sips and Toth models showed the best fit for the experimental data, indicating the heterogeneous nature of the adsorbent surfaces. The carbon dioxide adsorption kinetic was analysed using different kinetic models, obtaining that the adsorption process is both physical and chemical and that the limiting step of the diffusion process is intraparticle diffusion, although other processes are also involved such as diffusion through the boundary layer.