Artículos (Ingeniería Química y Ambiental)

URI permanente para esta colecciónhttps://hdl.handle.net/11441/11382

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Biomass-to-Ethylene: A techno-economic perspective on multiple feedstocks
(Elsevier, 2026-06) Caraballo-Bello, José; Rodríguez-Lugo, José Luis; Cabrera-Gallardo, Domingo; Baena-Moreno, Francisco M.; Vidal Barrero, Fernando; Ingeniería Química y Ambiental; Universidad de Sevilla
This paper focuses on the synthesis of ethylene from various biomass feedstocks, with ethanol as a transitional chemical platform. Four different production routes are investigated: two first-generation pathways using sugarcane and cereal crops (e.g., corn), and 2 s-generation alternatives based on lignocellulosic materials (e.g., corn stover, wheat straw). An analysis orientated to technological performance and economic feasibility comparison is established in depth. The reference facility is modelled with an annual output of approximately 117,000t of ethylene, which would be suitable for industrial-scale deployment. The project results include material and energy balances, along with a financial evaluation using metrics such as the Net Present Value (NPV) and the Minimum Ethylene Selling Price (MESP). Among all scenarios addressed, no route initially emerges as an economically viable option under current assumptions. However, it can be stated that the sugar-based ethylene production pathway reaches the best economic results, producing an NPV of -€173M€ at current ethylene prices and an MESP of €1265/t of ethylene. The remaining pathways require cost reductions (i.e., reducing biomass purchasing cost, maintenance and overhead, and consumptions) to achieve profitability. Sensitivity analyses state the significant influence of biomass procurement costs and market price fluctuations on economic outcomes. Overall, the findings of this research underscore the promise of bioethylene as a value-added chemical, supporting broader efforts toward decarbonization.
Estimation of methane production through the anaerobic digestion of greenhouse horticultural waste: A real case study for the Almeria region
(Elsevier, 2022-02) Gallego Fernández, Luz Marina; Portillo Estévez, Esmeralda; Navarrete Rubia, Benito; González-Falcón, Rocío; Ingeniería Química y Ambiental; Universidad de Sevilla; Corporación Tecnológica de Andalucía; Holcim España S.A.; Agencia de Innovación y Desarrollo de Andalucía (IDEA)
The methane production of greenhouse horticultural waste (GHW) from Almeria (Spain), from where fruits and vegetables are exported to all parts of Europe, was calculated in this work through a combination of experimental and theoretical methods. To this end, eight samples of GHW were collected and characterized in a waste treatment plant. The collection of samples was fairly distributed throughout the year to ensure a representative characterization. The amount of methane produced in a hypothetical anaerobic digestion process was predicted through empirical models fed by experimental data. The experimental characterization revealed that GHW contained an adequate content of volatile matter (65.72% TS), but a high value for total dry matter (53.46%) and lignin content (9.36%), as well as a low moisture content (46.54%) and C/N ratio (17.46). Inhibiting compounds were also observed in the characterization, such a S (0.43%) and Cl (1.41%). The methane production predicted was 0.229 Nm3 CH4/kg volatile matter, which may seem low in comparison to other waste potentially usable for anaerobic digestion. Nonetheless, the co-digestion of GHW with other waste could be an interesting alternative to enhance methane production and solve seasonality issues. Suitable pre-treatment can be also explored to increase the usability of GHW in anaerobic digestion. All in all, this work establishes a theoretical basis for potential solutions to manage the GHW produced in Almeria.
Multiscale analysis of carbon microfiber reinforcement on fracture behavior of ultra-high-performance concrete
(Elsevier, 2025-05) Ríos Jiménez, José David; Cifuentes-Bulté, Héctor; Ruiz, G.; González, D.C.; Vicente, M.A.; Yu, R.C.; Leiva Fernández, Carlos; Mecánica de Medios Continuos y Teoría de Estructuras; Ingeniería Química y Ambiental; Ministerio de Ciencia e Innovación (MICIN). España
This study delves into the intricate world of ultra-high-performance concrete, specifically how its mechanical integrity and fracture resistance are influenced by the incorporation of carbon microfibers of varying lengths. Employing a suite of multiscale analytical techniques, we link the mechanical attributes of concrete to its microstructural composition, with a keen focus on porosity distribution as revealed by advanced X-ray computed tomography and porosimetry assessments. We uncover how the selection of microfiber type affects the concrete’s internal pore landscape, which in turn dictates the material’s fracture behavior. An innovative use of inverse analysis, based on established fracture mechanics, allows us to formulate cohesive laws for the fracture process zone. Our results uncover a direct correlation between the variability in fracture properties and the specific types and amounts of fibers used, providing mix designers with critical insights for customizing concrete formulations to meet precise performance criteria.
The effect of using thermocouples on the char particle combustion in a fluidized bed reactor
(Elsevier, 2017-11) Salinero González, Jesús; Gómez Barea, Alberto; Fuentes Cano, Diego Javier; Leckner, Bo; Ingeniería Química y Ambiental; Ministerio de Economía y Competitividad (MINECO). España
The char temperature during combustion in a fluidized bed (FB) is often measured by thermocouples due to simplicity, and because it is assumed that the thermocouple effect on the movement of the char is negligible. It is also accepted that the combustion temperature of a char particle fluidized with an embedded thermocouple is similar to a freely fluidized particle. However, few publications have given evidence of this fact. In the present article this question is dealt with by comparing the evolution of conversion and temperature of fluidized char particles with and without an embedded thermocouple. Char from beech wood, sub-bituminous and bituminous coal of an initial diameter of 10 mm is burnt in two laboratory FBs; one 2-dimensional made of quartz with rectangular cross-section allowing visual observation and temperature tracking of the particles, and the other being 3-dimensional with 50 mm internal diameter. The surface temperature of the char particles is followed by a recently developed visual technique, based on pyrometry coupled with a digital camera. The consumption of char is evaluated by sampling particles from the bed at different stages of conversion, analyzing the density and size of the particle. It is found that, due to the greater resistance of the particle-thermocouple to the drag of the bed, the time that the char particle is in the bubble phase is 40% longer when the thermocouple is used, leading to higher combustion rate and temperature, and consequently, shorter burnout time. Moreover, the rotation of the char particle is restricted, provoking a non-homogeneous consumption of char, which enhances the size reduction of the particle along the direction perpendicular to the insertion of the thermocouple. Overall, these findings suggest that conclusions about char conversion by temperature measurements using thermocouples should be made with caution, since significant error might be committed under some operating conditions.
Measurement of char surface temperature in a fluidized bed combustor using pyrometry with digital camera
(Elsevier, 2016-03) Salinero González, Jesús; Gómez Barea, Alberto; Tripiana, M.; Leckner, Bo; Ingeniería Química y Ambiental; Ministerio de Ciencia e Innovación (MICIN). España
A method is presented to measure the char surface temperature during conversion in fluidized bed (FB) using a digital camera. The method applies one-color pyrometry (P1C) sequentially for the three wavelength bands (red, green, and blue) changing from one band to another automatically as a function of radiation intensity received by the sensor of the video camera. Experiments were made in a two-dimensional FB combustor (0.18 × 0.50 × 0.018 m) equipped with a window for visual observation. It is shown that the new method improves the accuracy compared to two-color pyrometry (P2C), allowing the measurement of a wider range of temperature, including temperatures lower than the bed (background). The main limitation of P1C (compared to P2C) is that the char emissivity has to be known. However, a sensitivity analysis, assuming a char emissivity variation from 0.85 to 1, reveled that the relative error in temperature is lower than 1% when the surface temperature of the char is higher than that of the bed. Then an assumed value of emissivity within this range is sufficient. However, a more precise estimate of char emissivity is needed when measuring temperatures lower than the bed temperature. Furthermore, the method enables determination of details such as surface temperature gradients and size of the particle during combustion. Overall, the technique allows determination of precise data of the fuel conversion process in FB.
The influence of CO2 gas concentration on the char temperature and conversion during oxy-fuel combustion in a fluidized bed
(Elsevier, 2018-04) Salinero González, Jesús; Gómez Barea, Alberto; Fuentes Cano, Diego Javier; Leckner, Bo; Ingeniería Química y Ambiental; Ministerio de Economía y Competitividad (MINECO). España
In spite of the extensive theoretical and experimental work carried out on coal/char oxy-combustion in a fluidized bed (FB), the effect of changing the atmosphere from O2/N2 to O2/CO2 for a high O2 concentrations is not entirely understood. In this work, experiments with single char particles are conducted in a bi-dimensional FB at 800 and 850 °C, varying the O2 concentration from 11 to 50%v/v in N2 or CO2. The FB reactor has a quartz window for visual observation, allowing the measurement of temperature and tracking the char conversion process by pyrometry with a digital camera. The method is shown to overcome the inherent limitations of other methods used in FB, such as thermocouples or pyrometry with an optical probe. Results indicate that the transfer of O2 from the bulk gas of the bed to the surface of a char particle controls the overall rate of char conversion in O2/N2 and in O2/CO2. In the latter gas mixture, the carbon consumption by gasification is significant even at a relatively low char temperature (850 °C). This additional carbon consumption makes the apparent char consumption rate in both atmospheres roughly equal (at the same O2 concentration) for char temperatures below 925 °C, and higher in O2/CO2 than in O2/N2 for char temperatures above 925 °C. Moreover, during the time in which the char stays in the emulsion phase, its temperature is roughly the same in both atmospheres, but when the char is in the bubble or splash zone its temperature is much higher than that in the emulsion phase. As a result, the difference in char conversion rate, observed in both atmospheres, is mainly controlled by the time in which the char particle is out of the emulsion phase. These results underline the importance of paying attention to the movement of a char particle through the different phases of the bed in order to improve the understanding of the oxy-fuel behavior in FB.
Measurement and theoretical prediction of char temperature oscillation during fluidized bed combustion
(Elsevier, 2018-06) Salinero González, Jesús; Gómez Barea, Alberto; Fuentes Cano, Diego Javier; Leckner, Bo; Ingeniería Química y Ambiental; Ministerio de Economía y Competitividad (MINECO). España
There is experimental evidence of oscillations of the char particle temperature during combustion in a fluidized bed (FB), resulting from the movement of the char throughout the bed. However, in most theoretical FB combustion studies the char particle is assumed to always stay in the emulsion phase, and existing models do not take into account the movement of the char particle explicitly. Moreover, it is difficult to quantify the magnitude and frequency of these temperature oscillations with the common measurement techniques employed in FB (thermocouple and pyrometry with optical probe). In this work, the combustion of single char particles (8 mm) from beech wood and sub-bituminous coal is carried out in a 2-dimensional FB made of quartz, using two O2 concentrations (11 and 21%v) in N2. The time-evolution of the temperature and the size of the char in the different phases are estimated by the analysis of images resulting from a new method combining pyrometry with readings from a digital camera. It is found that the combustion temperature oscillates in hundredths of seconds with an amplitude varying from 10 to 100 °C, resulting from the movement of a particle between the emulsion, bubble and splash phases. The amplitude increases with higher O2 concentration and smaller char-particle size. A combustion model is developed using the experimental characterization of the movement of the char particle through the bed as input. The temperature and burnout time predicted by the model compare well (within 15 %) with measurements obtained from this work and from literature.
The influence of volatiles to carrier gas ratio on gas and tar yields during fluidized bed pyrolysis tests
(Elsevier, 2018-08) Fuentes Cano, Diego Javier; Salinero González, Jesús; García Haro, Pedro; Nilsson, Susanna Louise; Gómez Barea, Alberto; Ingeniería Química y Ambiental; Junta de Andalucía; Ministerio de Economía y Competitividad (MINECO). España; Universidad de Sevilla
The formation of tar and light hydrocarbons during pyrolysis of pruning waste pellets in a fluidized bed (FB) reactor was experimentally studied as a function of temperature (700–900 °C), gas residence time (0.8–2.0 s) and volatiles to carrier gas ratio (13/87–42/58 vol%). The latter is defined as the ratio between the volume flowrates of volatiles released from the fuel particle at a given instant and that of the carrier gas used for the experiment at the same instant, and it quantifies the concentration of volatiles in the bulk gas. Experiments were conducted to analyze separately the effect of each of these three parameters on the yield of the different pyrolysis products. Special attention was paid to study the influence of the concentration of volatiles in the gas (controlled by changing the carrier gas/fuel ratio), since this parameter has been usually neglected in lab-scale kinetics studies up to now. The yields of the main light gases CO, CO2, H2, C1-C3 hydrocarbons as well as 41 tar compounds, grouped in five families, are reported. The increase in the reactor temperature strongly influenced the composition of the gas, reducing the yield of light hydrocarbons, and aliphatic and heteroatomic tars, and increasing the yield of CO, H2, benzene and polyaromatic hydrocarbons (PAH). The variation of the gas residence time between 0.8 and 2.0 s showed only slight influence on the yields of pyrolysis products. Remarkably, the increase in the concentration of volatiles from 13 to 27 (vol%) was seen to significantly affect the composition of the tar mixture, leading to higher yield of PAH while the yields of monoaromatic hydrocarbons decreased. This result highlights the significance of the concentration of volatiles during the study of the evolution of pyrolysis products.
Biogas upgrading in a pilot scale rotating packed bed absorber
(Elsevier, 2026-01) Salinero González, Jesús; Gallego Fernández, Luz Marina; Portillo Estévez, Esmeralda; Navarrete Rubia, Benito; Vilches Arenas, Luis Francisco; Ingeniería Química y Ambiental; Ministerio de Ciencia e Innovación (MICIN). España
Biogas upgrading is typically carried out using chemical absorption in conventional packed columns. However, its high energy consumption and limited profitability highlight the need for alternative technologies. The Rotating Packed Bed (RPB) absorber could be a promising alternative, as it improves mass transfer, reduces size and energy consumption, and resists flooding more effectively. Given that RPB absorbers have not yet been experimentally applied to biogas upgrading, this work addresses this gap by first characterizing a pilot-scale unit using simulated biogas (39 %v/v CO2 in N2) and sodium hydroxide as the absorbent. Them, 11 Nm3/h of synthetic biogas (36 %v/v CO2 in CH4 and other trace gases) is upgraded using the optimized working conditions obtained from this characterization. Characterization tests assess CO2 removal efficiency based on rotational speed (300 - 2400 rpm) and absorbent concentrations (1 M and 2 M), treating 10.7 Nm3/h of simulated biogas with 0.19 m3/h (2 M) and 0.38 m3/h (1 M) of absorbent solution. Results show that increasing rotational speed reduces CO2 concentration, reaching a minimum of 2.1 %v/v at 1800 rpm with 96.7 % removal efficiency. Between 600 rpm and 2400 rpm, outlet CO2 concentrations meet the requirements for fuel and grid application. Biogas upgrading achieves 95.1 % efficiency with 2.9 % CO2 concentration, with a height of a transfer unit (HTU) an order of magnitude lower than in conventional packed beds. Finally, data reliability and RPB performance are validated by sodium and carbon mass balances, with discrepancies up to 15 % and between 6 % and 21 %, respectively.
Improved recycling of a gasification fly ash: An integrated waste management approach within the framework of a Circular Economy
(Elsevier, 2024-10) Fernández Pereira, Constantino; Leiva Fernández, Carlos; Luna Galiano, Yolanda; Vilches Arenas, Luis Francisco; Arroyo Torralvo, Fátima; Ingeniería Química y Ambiental; Junta de Andalucía; European Union (UE)
A Circular Waste Management alternative is considered in this paper in which a complete ash valorization process is proposed for an Integrated Gasification with Combined Cycle fly ash, trying to extract maximum value from this waste before it is discarded. In the paper, germanium, a scarce resource vital in our modern society, is first extracted from fly ash using water, with an extraction yield of 85%, and subsequently, the leached fly ash is used in the manufacture of fire-resistant boards containing 60% ash, thereby avoiding its disposal in a landfill. The potential environmental impact caused by the two stages of the process was analyzed, and the final effluent was considered to achieve a zero-discharge objective. This paper contributes to the development of a more sustainable management alternative for an industrial waste produced in increased amounts and provides the basis for a symbiotic coupling relationship among various industrial sectors.
Study of seashell waste recycling in fireproofing material: technical, environmental, and economic assessment
(Elsevier, 2021-10) Peceño, Begoña; Alonso-Fariñas, Bernabé; Vilches Arenas, Luis Francisco; Leiva Fernández, Carlos; Ingeniería Química y Ambiental; Gobierno Regional de Coquimbo (Chile)
The productive sector must incorporate waste into traditional materials in order to grow sustainably. In Galicia (Spain) alone, the canning industry produces over 150,000 metric tons of seashell waste per year. Most of this waste is still disposed of in landfills or open fields due to the lack of a technically feasible, environmentally sustainable, and economically profitable recycling alternative. This paper aims to study the feasibility of a new recycling alternative for seashell waste from industrial canning, based on the production of fireproof material suitable for construction use. The waste was pre-treated in order to remove salts and remaining organic matter and reduce particle size. According to international standards, physical, mechanical, and insulating properties were assessed for four compositions: 0, 40, 60 and 80% of gypsum substituted with pre-treated seashell waste. Results showed that substitution of up 60% gypsum was technically feasible. A Life-Cycle Assessment and a preliminary production cost analysis were performed by analysing a recycling case in Galicia. The case study found that 40–60% gypsum substitution obtained an environmental impact reduction of 0.4%–59% for 13 of the 18 impact categories considered compared with 0% substitution. Increases in the other 5 categories were analysed due to aquatic emissions released in the waste pre-treatment washing process. The locations of the fireproof material production facility and the waste source were a key factor. Production costs could be reduced by 20–31% by using 40–60% gypsum substituted with seashell wastes.
Sustainable management of spent fluid catalytic cracking catalyst from a circular economy approach
(Elsevier, 2020-06) Alonso-Fariñas, Bernabé; Rodríguez Galán, Mónica; García Arenas, Celia; Arroyo Torralvo, Fátima; Leiva Fernández, Carlos; Ingeniería Química y Ambiental
For sustainable growth, an economic model must tend toward a circular system, especially in the field of waste management. This work focuses on the valorization of spent fluid catalytic cracking catalyst from oil refineries, which generate 400,000 metric tons of spent catalyst per year worldwide, most of which is sent to landfills. A new alternative to landfilling is proposed for this waste, based on the combination of acid leaching for the recovery of lanthanum, a valuable rare earth, and the reuse of the leached solid residue as a cement substitute. A comparative life cycle assessment was made, including four environmental impact categories, i.e. global warming, fossil resource scarcity, mineral resource scarcity and water consumption, in order to quantify the potential environmental benefits of secondary lanthanum recovery from industrial waste with respect to primary lanthanum extraction from mineral resources. A maximum of 85.6% La recovery was achieved and 15 wt% of cement can be substituted with leached solid residue without changing the original cement classification. The waste management process presented in this paper promotes the sustainable management of the spent fluid catalytic cracking catalyst and contributes to the development of a new resource for a critical material such as lanthanum. The implementation of this novel waste management process could reduce global warming and mineral resource scarcity but would increase fossil resource scarcity and water consumption in comparison with primary La extraction.
Use of Liquid Industrial By-Products as Biostimulants in the Remediation of Hydrocarbon-Contaminated Soils
(Multidisciplinary Digital Publishing Institute (MDPI), 2025-12) Ritoré, Emilio; Arnáiz Franco, Carmen; Morillo Aguado, José; Egea-Corbacho, Ágata; Usero García, José; Ingeniería Química y Ambiental; Corporación Tecnológica de Andalucía
Soil contamination by petroleum hydrocarbons represents a significant environmental challenge, especially in industrial and urban areas. This study evaluates the use of three industrial liquid by-products—sludge dewatering sidestream (SD), leftover yeast (LY), and secondary clarifier effluent (SC)—as biostimulant agents for the bioremediation of soils contaminated with gasoline and diesel mixtures. The novelty lies in applying these waste streams within a circular economy framework, with the added advantage that they can be injected directly into the subsurface. Microcosm tests were conducted over 20 weeks, analyzing the degradation of total petroleum hydrocarbons (TPHs) and their aliphatic and aromatic fractions using gas chromatography. The results show that all by-products improved biodegradation compared to natural attenuation. LY was the most effective, achieving 73.2% TPH removal, followed by SD (70.6%) and SC (65.4%). The greatest degradation was observed in short-chain hydrocarbons (C6–C16), while compounds with higher molecular weight (C21–C35) were more recalcitrant. In addition, aliphatic hydrocarbons showed greater degradability than aromatics in heavy fractions. Kinetic analysis revealed that the second-order model best fitted the experimental data, with higher correlation coefficients (R2) and more representative half-lives. Catalase enzyme activity also increased in soils treated with LY and SD, indicating higher microbial activity.
Plasma-flash sintering II: Flashing ZnO at room temperature using low AC voltage
(Wiley, 2025-11) Gil González, Eva; Manchón Gordón, Alejandro F.; Perejón Pazo, Antonio; Sánchez Jiménez, Pedro Enrique; Pérez Maqueda, Luis A.; Ingeniería Química; Química Inorgánica; Física de la Materia Condensada; Ministerio de Ciencia e Innovación (MICIN). España; Junta de Andalucía
In this study, we have advanced the plasma-flash sintering (PFS) technique by demonstrating the preparation of dense ZnO ceramics at room temperature using a moderate electric field of 250 V cm−1 under a low-pressure nitrogen atmosphere. This specific environment facilitates the sequential occurrence of plasma generation followed by the flash sintering event. Compared to traditional flash sintering technique, our approach significantly reduces both energy consumption and processing time, while eliminating the need for a furnace. Impedance spectroscopy confirms that ZnO ceramic produced via this method exhibits enhanced electrical conductivity. Hence, PFS is shown to be a potential tool for tuning the electrical properties of sintered materials at room temperature while boosting energy efficiency.
Nanosilica synergy: unveiling the strength and fracture mechanisms in advanced concrete composites
(Consejo Superior de Investigaciones Científicas (CSIC): Instituto Eduardo Torroja, 2025) Ríos Jiménez, José David; Ruiz López, Gonzalo; González Cabrera, Dorys Carmen; Cifuentes-Bulté, Héctor; Vicente Cabrera, Miguel Ángel; Yu, Rena Chengxiang; Leiva Fernández, Carlos; Mecánica de Medios Continuos y Teoría de Estructuras; Ingeniería Química y Ambiental; Ministerio de Ciencia e Innovación (MICIN). España; TEP972: Mecánica de Materiales y Estructuras; TEP142: Ingeniería de Residuos
This study explores how nanosilica impacts the mechanical properties and fracture behavior of ultra-high-performance concrete (UHPC). We delved into the role of nanosilica in enhancing pozzolanic reactions and its effects on UHPC’s pore structure. This was investigated using advanced techniques such as scanning electron microscopy and mercury intrusion porosimetry. We prepared UHPC samples with varying nanosilica concentrations, replacing cement by 0 to 7.5%wt, to understand its influence comprehensively. Our findings reveal that higher nanosilica content, while beneficial in some aspects, compromises the self-compacting nature of UHPC. This necessitated conducting slump tests to evaluate workability. Remarkably, the addition of nanosilica led to a reduction in both capillary and macropores, enhancing the density and strength of the concrete. Specifically, a maximum of 5%wt nanosilica addition resulted in a 13% increase in compressive strength. However, this improvement in strength comes with a trade-off. The fracture energy of UHPC decreased by 23.2%, indicating an increase in brittleness due to nanosilica. Interestingly, tensile strength saw a 10.5% increase, primarily attributed to the enhanced formation of the C-S-H gel, a key component for concrete strength. This study illuminates the dual-edged effects of nanosilica in UHPC, presenting a nuanced view of its role in concrete technology and fracture mechanics.
The Impact of Steel Fiber Length and Dosage on Microstructure and Mechanical Performance in UHPFRC: A Hybrid Approach
(Asociación Española de Ingeniería Estructural (ACHE), 2025) Ruiz Martínez, Jaime Delfino; Ríos Jiménez, José David; Pérez-Soriano, Eva María; Cifuentes-Bulté, Héctor; Leiva Fernández, Carlos; Ingeniería Química y Ambiental; Mecánica de Medios Continuos y Teoría de Estructuras; Ingeniería y Ciencia de los Materiales y del Transporte; Ministerio de Ciencia e Innovación (MICIN). España
This study evaluates the effects of steel fiber length (6 and 13 mm) and dosage on the microstructural and mechanical properties of an ultra-high-performance fiber-reinforced concrete (UHPFRC). The incorporation of 6 mm fiber significantly improved the material's workability characteristics. Microscopic evidence indicates better alignment and distribution of 13 mm fibers within the concrete matrix compared to 6 mm fibers, resulting in reduced porosity and enhanced matrix-fiber interaction. Mechanical testing confirmed that the inclu-sion of 13 mm steel fibers at various dosages consistently outperformed 6 mm fibers in enhancing compressive and flexural strengths. The optimal dosage, among those tested, for compressive strength was found to be 196 kg/m³ with 13 mm fibers, while the best performance in flexural strength was observed at 226 kg/m³. To address the challenges inherent in UHPFRC—specifically the intricate metallic fiber distri-bution and limited workability prompted a comprehensive investigation into fiber mixture optimization strategies. Hybrid fiber approach was explored by substituting 10%, 20%, and 30% of the 13 mm fiber dosage (196 kg/m³) with 6 mm steel fibers. Among these, the mix containing 80% of 13 mm steel fibers and 20% of 6 mm steel fibers demonstrated the highest flexural strength, even than those with higher steel fiber content (226 kg/m3). This hybridization suggests an optimized combination of fiber lengths for enhanced flexural performance without compromising compressive strength, providing insights into effective fiber-reinforcement strategies for UHPFRC applications.
Ultrasonic Processing and Its Impact on the Rheology and Physical Stability of Flaxseed Fiber Dispersions
(Multidisciplinary Digital Publishing Institute (MDPI), 2025-07-25) Alfaro Rodríguez, María del Carmen; García-González, María Carmen; Muñoz García, José; Ingeniería Química
Ultrasonic homogenization is an emerging technique with significant potential to modify the structure and functionality of food ingredients. This study evaluated the effect of ultrasonic homogenization on the rheological behavior and physical stability of aqueous dispersions of flaxseed fiber. Flax mucilage, with health-promoting and techno-functional properties, is of growing interest in several industries. The samples were subjected to different ultrasonic treatments, varying in amplitude (from 40 to 100%) and duration (from 2 to 20 min), with and without preliminary rotor–stator homogenization. The rheological properties were analyzed using small-amplitude oscillatory shear (SAOS) tests and steady shear flow curves. Physical stability was assessed by multiple light scattering. The results revealed that short treatment under ultrasonic homogenization had minimal impact on the viscoelastic parameters and viscosity, regardless of the amplitude used. However, longer treatments significantly reduced both values by at least one order of magnitude or more, indicating the occurrence of microstructural degradation. The relevance of this research lies in its direct applicability to the development of functional foods, since it is concluded that control of the ultrasonic homogenization process conditions must be carefully selected to retain the desirable rheological properties and physical stability.
Techno-economic analysis of the production of n-butanol from different biomass sources
(Elsevier, 2025) Caraballo Bello, José; Rodríguez Lugo, José Luis; Baena-Moreno, Francisco M.; Vidal Barrero, Fernando; Ingeniería Química y Ambiental
This study evaluates the production of n-butanol from different biomass sources, using ethanol as an intermediate platform. The analysis considers four biomass-based production pathways: two first-generation routes, which use sugarcane and cereals (such as corn), and two second-generation routes, which utilize lignocellulosic biomass such as corn stover and wheat straw. This approach enables the comparison of different technologies in terms of efficiency and economic viability. The studied plant has a production capacity of nearly 94,000 tons of n-butanol per year, positioning it as a viable option for industrial-scale assessments. The developed models account for material and energy balances, as well as a detailed economic analysis based on indicators such as Net Present Value (NPV) and Minimum Butanol Selling Price (MBSP). Among the analyzed pathways, results show that the sugar-based pathway is the only fully profitable option under the evaluated conditions. This pathway achieves an NPV of 362 M€ and an MBSP of 954 euros per ton. Conversely, the other pathways require technological optimizations and reductions in investment costs to achieve profitability. Additionally, the sensitivity analyses conducted reveal the strong dependency of each pathway profitability on the biomass purchase price and the selling price of n-butanol itself. All in all, this study highlights the potential economic viability of n-butanol not only as a high-value-added chemical product but also as a sustainable alternative to traditional fuels, contributing to the transition towards a decarbonized economy.
Development of Acoustic Absorbent Materials Using Pine Needles
(Multidisciplinary Digital Publishing Institute (MDPI), 2025-10-31) Ruiz Martínez, Jaime D.; Peceño, Begoña; Carrasco Carrasco, Carlos Jesús; Orejón, Daniel; Luna Galiano, Yolanda; Leiva Fernández, Carlos; Ingeniería Química y Ambiental; Ministerio de Ciencia e Innovación (MICIN). España
Acoustic absorbing materials made from waste plants or trees represent a sustainable source for noise reduction products and applications such as home acoustic insulation and/or traffic road noise reduction barriers. The primary aim of this work is hence to demonstrate the potential application of pine needle waste as the main constituent in acoustic absorbing materials while resin is used as binder. Once the samples have been manufactured, their different physical (density and porous structure), mechanical (compressive strength), and sound-insulating (sound absorption coefficient) properties are characterized. The influence of the ratio of pine needle/resin, length of the pine needle fragments, and thickness of the samples on the different properties has been explored. As the ratio of pine needles/resin increases so does the porosity, although the compressive strength decreases. To highlight this, the noise reduction coefficient is in the range of 0.67 and 0.71 (for 4 cm of thickness), which is higher than that reported for other typical sound absorption materials. An excess of resin produces a clogging phenomenon at the bottom of the samples, producing a reflective layer instead of an absorbent one, which could be used positively to increase the acoustic absorption coefficient in materials with combinations of sections with different needle/resin ratios. Owed to its low weight and high sound absorption coefficients at low frequencies (characteristic of road noise), PN finds usefulness in the manufacturing of environmentally friendly sound-absorbing materials as road insulation barriers.
Impact of solar thermal energy and calcium looping implementation on biomass gasification for low-carbon hydrogen production
(Elsevier, 2025) Aragón García, Alejandro; Villanueva Perales, Ángel Luis; González, William A.; Fuentes Cano, Diego Javier; Alonso-Fariñas, Bernabé; Gómez Barea, Alberto; Ingeniería Química y Ambiental; Ministerio de Ciencia e Innovación (MICIN). España; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); Universidad de Sevilla
In the search of low-carbon hydrogen production routes, this study evaluates four biomass gasification processes: conventional steam gasification (CSG), sorption-enhanced gasification (SEG), and their solar-assisted variants (SSG and SSEG). The comparison focuses on three key aspects: hydrogen production, overall energy efficiency (to H2 and power), and carbon capture potential (generation of a pure CO2 process stream for storage or utilization). For a realistic comparison, a pseudo-equilibrium model of a double-bed gasifier was developed based on experimental correlations of char conversion under conventional and SEG conditions. The solar processes were designed for stable year-round operation, considering seasonal weather variations by appropriately dimensioning the heliostat field and the thermal and chemical energy storage systems, whose inventory dynamics were modelled. Both the gasifier and central solar tower models were rigorously validated with published data, enhancing the reliability of the results. Solar-assisted configurations significantly outperform non-solar ones in hydrogen production, with SSEG yielding 128 kg H2/ton biomassdaf compared to 90–95 kg for non-solar options. SEG demonstrates superior carbon capture potential (76 %), while solar-assisted systems achieve higher energy efficiency (67–73 % vs. 60–63 % for non-solar). These results underscore the potential of solar-assisted gasification for sustainable hydrogen production, offering enhanced yields, improved efficiency, and substantial carbon capture capabilities. Future work will involve economic and environmental analysis to determine the best overall configuration.

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