Articles publicats en revistes (Ciència dels Materials i Química Física)

URI permanent per a aquesta col·leccióhttps://hdl.handle.net/2445/9243

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Mostrant 1 - 20 de 1424

Hybridization of Salt Hydrates with Solid–Solid Phase Change Materials: A Novel Pathway to Sorption Thermochemical Materials Manufacturing
(Wiley-VCH, 2023-05-13) Palacios, A.; Navarro, M.E.; Barreneche, Camila; Ding, Y.
Major advancements are needed in the thermochemical energy storage (TCES) field to bring the technology to commercial levels. The current research strategies are focused on improving heat and mass transfer using different supporting materials to achieve mechanical integrity during storage. However, these strategies are still under development, and they have not overcome the lab scale yet. This work explores novel matrices to expand the material database for TCES composites. Pure structural matrices (cellulose) and novel matrices with storage potential (polymeric solid–solid phase change materials) are selected and combined with three well-known thermochemical materials (TCMs) (MgSO4·6H2O, SrBr2·6H2O and MgCl2·6H2O), providing evidence of hybridized composites with storage capacity up to 2.4 GJ m−3 with a 25–20 wt% of polymeric matrix. The polymer content is found to act as a nucleating agent in the magnesium sulfate crystallization process forming a synthetic monohydrate crystalline phase (Kieserite) and inhibiting the formation of the amorphous phase. The effect of the matrix is proved to induce certain structural deformation or changes not observed in the pure TCM sorption process. This phenomenon has the potential to benefit the stabilization of the TCM, e.g., inhibition of the formation of amorphous phase in magnesium sulfate composites.
Performance analysis of a novel multi-module columnar packed bed reactor with salt hydrates for thermochemical heat storage
(Elsevier, 2024-05-01) Hao, C.; Feng, G.; Ma, C.; Barreneche, Camila; She, X.
The thermochemical heat storage based on salt hydrate has great advantages of high energy storage density and applicability to seasonal heat storage. In conventional packed-bed reactors, salt hydrates are often simply accumulated, and the air diffuses inside the pores. As a result, the salt hydrates are prone to agglomeration during the reaction, which will reduce the performance. To address these issues, this paper designs a multi-module columnar packed-bed reactor. The performance of top peripheral air intake and bottom central air intake schemes is numerically compared, and the effects of working parameters, structural parameters and physical parameters are analyzed. The results show that the bottom central air intake scheme has obvious advantages of uniform reaction rate, short reaction time and small resistance loss compared with the top peripheral air intake scheme. It is found that the reaction time is shortened by 46.6 % and the heat storage efficiency increases from 80.4 % to 83.8 % when the inlet air temperature increases from 75 to 95 °C. Besides, the reaction time decreases by 20.7 % as the inlet air velocity increased from 1 to 3 m/s and the optimal spacing of the hydrated salt modules is 0.3 cm. These results are promoting the development of thermochemical heat storage.
Protective Laser Cladding Coatings for Thermal Energy Storage Tanks in contact with Molten Salt-Based Nanofluids
(Elsevier, 2026-04-06) Betancor, Lorena; Svobodova Sedlackova, Adela; Clave, Genís; Barreneche, Camila; Dosta Parras, Sergi
Intermittency of renewable energy sources is a critical problem. Concentrated Solar Power (CSP) power plants with thermal storage systems offer one of the main solutions. Among the many storage processes, nanofluids are a method of improving thermal performance but inducing corrosion of storage units. This study investigates the potential of Inconel-625 and Stellite-6 coatings deposited by laser cladding in preventing nanofluid-induced corrosion in CSP thermal storage units. AISI 316L stainless steel samples coated with Stellite-6 and Inconel-625 were tested for corrosion in NaNO3 containing SiO2 nanoparticles at 450 °C for 30, 60, and 90 days. Cross-section analysis was used to assess thickness loss, and coatings were analysed. Chemical attack enhanced material contrast for microstructural observation. Compositions of oxides were identified by EDS and XRD analysis, and ICP analysis identified elements in the salts after corrosion. Results showed almost no loss in thickness, even after 90 days, to substantiate the protective efficacy of coatings. Results confirm that Inconel-625 and Stellite-6 coatings are a reliable source of preventing corrosion caused by nanofluids in CSP thermal storage systems.
Experimental evaluation of carbon-coated sand as solar-absorbing and thermal energy storage media for concentrated solar power applications
(Elsevier, 2025-06-15) Rodríguez, J.B.; Majó, M.; Mondragón, Rosa; Barreneche, Camila; Díaz-Heras, M.; Canales-Vázquez, J.; Almendros-Ibáñez, J.A.; López Hernández, Leonor
Innovative systems using solid particles for solar energy capture, heat transfer, and thermal energy storage are emerging in next-generation concentrating solar power plants. This study investigates silica sand enhancement using novel coatings of graphite, carbon black, and glucose, evaluating their thermal stability, optical properties and durability under operational conditions. The coated samples were subjected to fluidisation and radiation treatments to simulate real-world conditions. Thermogravimetric analysis, specific heat capacity measurements, optical absorptance evaluation, and photothermal conversion efficiency testing were performed. The results show that graphite-coated sand exhibits superior optical and thermal performance, achieving a 44.9 % increase in photothermal conversion efficiency compared to uncoated sand. While carbon black coatings displayed higher absorptance, their heterogeneity compromised long-term effectiveness. Glucose coatings degraded above 280 °C, rendering them unsuitable. An industrial-scale fluidised bed model was used to assess the impact of the observed enhanced particle absorptance on the resulting performance of these systems, revealing thermal efficiency improvements of 50 %. These findings confirm that graphite-coated sand is a viable solution for high-temperature concentrating solar power plants applications, offering stable performance, enhanced light-to-heat conversion and improved energy efficiency in large-scale
Exploring the potential of a potash by-product for thermochemicalheat storage
(Elsevier, 2026-02-25) Mamani Challapa, Verónica Lisbeth; Gutiérrez, Andrea; Fernández Renna, Ana Inés; Ushak, Svetlana N.
Thermochemical energy storage is an effective method for seasonal heat storage applications, as it stores energy on a long-term basis. This process captures excess heat generated during the summer, whether from solar energy or surplus heat from supply chains, and utilizes it during the winter months. However, the process relies on chemical reactions, which pose various technical challenges. Additionally, it requires a significant amount of materials, leading to increased system costs. In this study, we propose to investigate potassium carnallite as a low-cost thermochemical material (TCM). This material is derived from potash saline deposits located in northeastern Spain. Characterization through chemical analysis revealed that it comprises 86.0% KCl·MgCl2·6 H2O, with NaCl as the main impurity at a concentration of 10%. The dehydration and hydration reactions analyzed involve the loss and retention of 4 molecules of H2O. Importantly, there is no evidence that the hydrolysis decomposition of the material affects the reversibility of these reactions. The study demonstrated a good reversibility of the reaction, with a yield of 81.73%, which decreased to 78.83% by the tenth cycle. These cycles simulate 10 years of seasonal use under specific conditions (PHy = 1.3 kPa, THy = 40 °C, PDe = 4.0 kPa, and TDe = 110 °C). Notably, natural carnallite exhibited 20% higher reversibility compared to synthetic carnallite. However, it was found to be 14% less reversible during the first cycle and 8.4% less reversible by the tenth cycle compared to another carnallite material studied under the same conditions previously. This difference in reversibility may be attributed to variations in the impurity content of both materials, where a higher concentration of NaCl in carnallite may act as a chemical spacing, facilitating water vapor mass transfer and consequently improving cycling stability. We measured an energy density of 0.892 GJ/m3 during the tenth hydration cycle, indicating that the winter energy needs of a household can be met using 9.0 m3 of thermochemical material. These findings suggest that by-products from mining, such as carnallite, are promising candidates for seasonal heat storage applications. However, improvements in the material are needed to increase the energy density at large scale, which would consequently reduce the volume of material required for the application using a reactor system.
Protective thermal spray coatings for TES applications in CSP plants
(Elsevier B.V., 2025-06-03) Betancor, Lorena; Svobodova Sedlackova, Adela; Clave, Genís; Barreneche, Camila; Dosta Parras, Sergi
Corrosion caused by using molten salts in thermal storage systems in Concentrated Solar Power (CSP) plants is a major problem in this field. To eliminate this problem, the use of nanofluids and the application of Inconel-625 coatings by thermal spray techniques (High Velocity Oxygen Fuel - HVOF and Cold Gas Spray - CGS) are proposed. This study focuses on evaluating the effectiveness of these coatings, deposited on AISI 316 stainless in mitigating nanofluid-induced corrosion in CSP plant Thermal Energy Storage (TES) systems. For this purpose, a total immersion test in NaNO<sub>3</sub> with silica nanoparticles was carried out in a furnace at 450 °C under air atmosphere for 30 days (720 h) and 90 days (2160 h). The test was also performed on SS316L and Inconel-625 bulk substrate samples for better comparison. Evaluation of corrosion behaviour relied on measuring the reduction in cross-sectional thickness of the test samples. Furthermore, detailed characterization was performed using Laser Scattering (LS), Scanning Electron Microscopy (SEM), and Field Emission Scanning Electron Microscopy (FESEM). The coating surface was also studied by X-Ray Diffraction (XRD), and the molten salt-based nanofluids were studied by Inductively Coupled Plasma (ICP). The results obtained revealed notably minimal corrosion rates per year for both deposition methods, after 3 months of testing. This demonstrates the effectiveness of both HVOF and CGS Inconel-625 coatings as a reliable solution to decrease the level of corrosion in TES units. However, future studies should be conducted over longer periods and with operating conditions closely replicating working conditions.
Understanding failure in austenitic steels: Key considerations for moltensalt storage in CSP applications
(Elsevier, 2026-02-26) Ardila Parra, Sergio Andrés; Prieto Ríos, Cristina; Osorio, Julian D.; Fernández Renna, Ana Inés
Owing to their excellent properties, austenitic stainless steels are extensively used in boilers, furnaces, molten salt tanks, and other applications that are subjected to extreme mechanical loads and high-temperature conditions. Their high corrosion and creep resistance make them suitable for high-temperature operating environments.Additionally, good fatigue resistance and favorable mechanical and visual properties are essential. However, the premature failure of several components at elevated temperatures has been previously reported. Although the failure analysis of components in service is complex, processes such as cold work and welding have been identified as contributing factors to the performance degradation of these steels. This study aims to analyze the various documented failure modes and mechanisms in austenitic steels, including creep, cracking, stress relaxation cracking, and fatigue, to better understand the multi-objective design requirements for these alloys as structural materials for high-temperature molten salt tanks in Concentrating Solar Power (CSP) plants. Stabilized austenitic grades, such as AISI 347H, demonstrate superior resistance to creep and corrosion-related degradation when compared to non-stabilized grades like AISI 316L at temperatures relevant to concentrated solar power (CSP) applications. In contrast, nickel-based alloys offer enhanced corrosion resistance, albeit at a higher cost. This review underscores that creep, stress relaxation cracking, and thermo-mechanical fatigue are the predominant long-term failure risks in CSP hot tanks.
Experimental validation of thermochemical water-sorption materials for thermal energy storage: Building application
(Elsevier, 2023-12-01) Palacios, A.; Navarro, M.E.; Barreneche, Camila; Ding, Y.
Salt hydrates for seasonal heat storage have emerged as an important research topic due to their potential to fulfil the heat demand in the residential and commercial building sector. However, the research undertaken has not yet covered key aspects of their fundamental thermal behaviour understanding e.g. experimentally validation, characterisation methodologies or material screening. The present investigation is aimed to identify promising thermochemical materials in the temperature range of 25–150 C, which are suitable for building applications and waste heat recovery. A list of ten salt hydrates has been screened through an experimental validation, which was developed and optimized for the specific working conditions. The salt hydrates were tested under operational conditions and key properties are assessed (thermal conductivity, specific heat, volume change, etc). Different case studies were used to narrow down to a list of final salts candidates under three theoretical working conditions scenarios for both open and closed systems. The cases of study prioritised high energy density (after one hydration/dehydration cycle), acceptable volume expansion and stability, which led to the final candidates. Magnesium sulphate was selected in the case of high energy density (>2 MJ/m3) and low cost (1 €/MJ), when lowering the energy density to 1 MJ/m3 calcium sulphate and copper sulphate were revealed as promising candidates for open and closed systems. While calcium nitrate was identified as a candidate along with magnesium sulphate when considering closed systems.
Life cycle assessment of a conventional thermal energy storage system versus an alternative steel slag-based system for concentrating solar power plants
(Elsevier, 2026-02-01) Vielma Leal, Carlos A.; Majó, M.; Calderon Diaz, Alejandro; Svobodova Sedlackova, Adela; Fernández Renna, Ana Inés; Barreneche, Camila
Thermal Energy Storage (TES) plays a crucial role in advancing decarbonisation. Its integration into Concentrated Solar Power (CSP) plants can significantly enhance efficiency and support renewable power generation. The primary commercial TES material, Solar Salt (SS), presents technical challenges and has the highest environmental impact in TES systems. An innovative alternative is Electric Arc Furnace Steel Slag (EAFSS), a steel industry by-product that can be repurposed as TES material. However, the environmental sustainability of EAFSS for TES applications has not been comprehensively studied. This research quantified the environmental impact of a thermocline TES system using EAFSS as a filler material, compared with a conventional SS system. A Life Cycle Assessment, employing mass and economic allocation methods, examined EAFSS environmental burdens across two SS reduction scenarios. A sensitivity analysis of EAFSS costs showed savings exceeding 30 % compared to SS. At the CSP plant level, the ReCiPe method indicated impact reductions of 9–10 % using mass allocation and 22–26 % with economic allocation. Global warming emissions were higher with mass allocation (0.400–0.408 kg CO2eq/kWh) than with the conventional TES system (0.358 kg CO2eq/kWh), which may benefit steelmaking industries by attributing a larger share of their emissions to CSP systems. In contrast, economic allocation yielded lower emissions (0.330–0.325 kg CO2eq/kWh), providing more credit to EAFSS for its valorisation. These findings underscore the potential of EAFSS to enhance CSP sustainability while valorising waste/by-products to generate greener electricity.
Methodology for the Prediction of the Thermal Conductivity of Concrete by Using Neural Networks
(MDPI, 2024-08-28) Rosa, Ana Carolina; Elomari, Youssef; Calderon Diaz, Alejandro; Mateu, Carles; Haddad, Assed; Boer, Dieter
The energy consumption of buildings presents a significant concern, which has led to a demand for materials with better thermal performance. Thermal conductivity (TC), among the most relevant thermal properties, is essential to address this demand. This study introduces a methodology integrating a Multilayer Perceptron (MLP) and a Generative Adversarial Network (GAN) to predict the TC of concrete based on its mass composition and density. Three scenarios using experimental data from published papers and synthetic data are compared and reveal the model’s outstanding performance across training, validation, and test datasets. Notably, the MLP trained on the GAN-augmented dataset outperforms the one with the real dataset, demonstrating remarkable consistency between the model’s predictions and the actual values. Achieving an RMSE of 0.0244 and an R2 of 0.9975, these outcomes can offer precise quantitative information and advance energy-efficient materials.
Thermodynamic modelling of a thermal energy storage packed bed tank: Exploring the influence of different particle sizes on overall performance
(Elsevier, 2025-05-30) Liu, Xianglei; Luo, Qingyang; Majó, M.; Calderon Diaz, Alejandro; Barreneche, Camila; Li, Jiawei; Tian, Yang; Fernández Renna, Ana Inés
Concentrated solar power combined with thermal energy storage (TES) technology is now widely employed in power generation. To enhance heat transfer efficiency during thermal charging and discharging processes, a packed bed TES system has been developed due to its high heat transfer rate and large heat transfer area. To unveil the overall performance of the packed bed, thermodynamic models are introduced to avoid problems like large size and complex structure. However, current developed models are too vague to study the size effect and pressure drop induced by the particle diameter. In this work, a two-solid-phase model is introduced to evaluate the size effect in packed bed TES systems during charging and discharging, utilizing molten salt and natural volcanic ash as the heat transfer fluid and main solid filler, respectively. Compared to single-phase packed bed, introducing small particles to occupy the void between the large particles yields a low void fraction, and thus the energy storage density is improved by 36.4 %. In the meantime, the thermal charging efficiency is enhanced from 54.37 % to 75.64 %. However, the pressure drop is inevitably increased because of the very low void fraction and the increased surface in contact with the fluid. The pressure drop follows an exponential trend with the changes in particle size. Furthermore, the thermocline in the packed bed requires careful consideration, as it corresponds to the location where the maximum pressure gradient occurs. This work provides insights into the effects of the packed bed induced by the particle size, offering valuable information for the design of next-generation TES packed beds.
Long-Term Compatibility Testing of Solar Salt and Solid Particles at High Temperatures: A Thermal and Chemical Characterization
(John Wiley & Sons, 2025-02-26) Majó, M.; Svobodova Sedlackova, Adela; Barcelona Pons, Pol; Fernández Renna, Ana Inés; Calderon Diaz, Alejandro; Barreneche, Camila
Thermal energy storage offers a viable solution to address the global energy problem of balancing the gap between the energy demand and the energy supply. One of the most advanced and mature thermal energy storage technologies in solar power technologies is a Concentrating Solar Power plant with a tower configuration and molten salts as thermal energy storage. Despite their advantages, molten salts also have limitations that include their corrosive nature, solidification at temperatures below 240°C, and high cost. Therefore, alternative thermal energy storage materials, such as solid-state thermal storage using concrete blocks or ceramic particles, are under research. Solid particles have a high thermal energy storage density, comparable to molten salts, and can withstand higher temperatures, making them well-suited for use in Concentrating Solar Power systems. The use of alternative materials for thermal energy storage is an important aspect of the circular economy concept, which aims to extract the maximum value from resources and reduce greenhouse gas emissions. This work aims to test the compatibility of Solar Salt with several alternative materials for use as thermal energy storage media, including silica sand, commercially sintered bauxite, and two different waste materials from the mining and steel industries. The study compares the thermal and chemical properties of these solid-molten salt mixtures with those of Solar Salt and quantifies the formation of nitrites in Solar Salt as a direct measurement of Solar Salt degradation. Additionally, a rheology study was conducted on the Solar Salt samples, revealing slight changes in viscosity attributed to the nitrite content. Although the thermal properties of the materials remained almost identical and natural and inert ceramic materials exhibited good compatibility, Solar Salt in contact with the waste materials exhibited the formation of nitrites, indicating an expected further degradation of the Solar Salt within these compounds.
Thermal cycling test of solar salt in contact with sustainable solid particles for concentrating solar power (CSP) plants
(MDPI, 2024-05-01) Majó, M.; Svobodova Sedlackova, Adela; Fernández Renna, Ana Inés; Calderon Diaz, Alejandro; Barreneche, Camila
Thermal energy storage (TES) is crucial in bridging the gap between energy demand and supply globally. Concentrated Solar Power (CSP) plants, employing molten salts for thermal storage, stand as an advanced TES technology. However, molten salts have drawbacks like corrosion, solidification at lower temperatures, and high costs. To overcome these limitations, research is focusing on alternative TES materials such as ceramic particles. These solids match molten salts in energy density and can withstand higher temperatures, making them well-suited for CSP systems. This study revolves around subjecting Solar Salt alone and Solar Salt alongside Volcanic Ash (VA) and Electric Arc Furnace Slag (EAFS) to a comprehensive thermal cycling test. This test is designed to assess the compatibility over the thermal cycles of the Solar Salt and the Solar Salt in contact with these solids in a CSP plant with a thermocline configuration. With a final thermal and chemical evaluation, our observations indicate that EAFS and VA demonstrate promising compatibility but an increase in the reduction rate of the Solar Salt due to a catalyst effect from EAFS in contact with the salt. No discernible alterations were detected in the properties of either the solid materials or solar salt when combined.
Mechanical-physical methods for paint removal of recycled bumpers for revalorization in the automotive industry
(Elsevier, 2024-11-05) Zambrano Membrives, Carla; Fernández Renna, Ana Inés; Tamarit, Pablo; Barreneche, Camila
The automotive industry uses plastics in the manufacture of car components due to their benefits such as weight reduction, high friction resistance, energy absorption, and versatility in blending with other materials and in its processability. A wide variety of plastic are used in vehicles. Although up to 13 different types of polymers may be used in a single car model, the most common is Polypropylene (PP). Nowadays, mechanical recycling is the most common method for recycling plastic waste from end-of-life vehicles in the automotive industry. However, challenges arise from material heterogeneity, presence of paint or impurities which affect mechanical properties and quality of recycled materials. Various chemical and physical methods to remove these impurities but economic, technical and feasibility considerations influence the adoption of technology in the industry. The current paper focuses on mechanical-physical procedures for paint removal from recycled automotive thermoplastics, aiming to maintain the properties of the polymer matrix and overcome environmental, economic and complex barriers. The used methods have shown success in removing paint from PP surfaces, with the pressing machine method with the best efficiency at a 38 % reduction. Despite not achieving over 90 % paint removal, these procedures establish fundamental principles for effective industrial mechanical paint depainting.
Evaluation of volcanic ash as a low-cost high-temperature thermal energy storage material for concentrated solar power
(Elsevier, 2024-04-30) Majó, Marc; Svobodova Sedlackova, Adela; Fernández Renna, Ana Inés; Calderon Diaz, Alejandro; Barreneche, Camila
The integration of renewable energy sources is facilitated by TES because it enables the storage and release of excess clean energy, which improves grid stability. In concentrating solar power plants (CSP), solar molten salt is frequently used since it has some advantages such as good thermal properties. However, certain challenges, such as molten salt corrosion, salt solidification, and high production costs, must be carefully considered. An alternative approach gaining attention involves the use of solid ceramic materials capable of withstanding high temperatures as a potential TES medium without the molten salt drawbacks. Elevating the operating temperature of power conversion processes while concurrently reducing capital costs is a strategic means to enhance the competitiveness of these innovative power plants. This study explores the potential of volcanic ash, a low-cost naturally occurring ceramic material, for TES. The evaluation revealed high-temperature stability up to 750 °C, slight mass gain but stable over time, elevated solar absorption, and excellent thermal and chemical stability, even in the presence of molten salts.
The limits of ground-state water splitting on ZnO surfaces: A density functional theory study
(Elsevier B.V., 2024-11-01) Morales Salvador, Raul; Bromley, Stefan Thomas; Viñes Solana, Francesc
The water (H2O) splitting reactions towards hydrogen (H2) and oxygen (O2) production in the ground state are here investigated on ZnO catalyst surfaces by means of density functional theory simulations. To this end, the Zn-terminated and O-terminated (0001) and (000̅) surfaces, respectively, and the non-polar (10̅0) and (11̅0) ones, have been investigated. The reaction thermodynamics has been analysed, being endergonic at normal conditions, and only exergonic at high temperatures and with high partial pressures of reactants. The adsorption of H2O, H2, O2, and reaction intermediates OH, O, and H, underlines the oxophylic character of Zn-terminated (0001) surface, as well as the H-phylic character of O-terminated (000̅) surface, while non-polar surfaces display both O- and H-phylic centers. The adsorption and co-adsorption strengths and elementary steps energy barriers along the reaction path pinpoint the key reaction limiting steps. The H2 formation step has a prohibitive barrier of 4.91 eV on the (000̅) surface, and a more moderate barrier of 2.33 and 1.83 eV for the non-polar (10̅0) and (11̅0) surfaces respectively. On the (0001) surface, the rate limiting step is O2 formation, with an energy barrier of 4.94 eV. Regardless of the surface, a higher affinity towards water would be a way to improve the reaction catalysis. The possible modification of surfaces to reduce the energy costs of the limiting steps are discussed, including the use of light-triggered ZnO catalyst, as well as the simultaneous presence of different surfaces to better split the different reaction steps in an energetically more efficient fashion.
Development of persulfate-based advanced oxidation processes to remove synthetic azo dyes from aqueous matrices
(Elsevier Ltd., 2024-05-01) Brillas, Enric; Oliver Pujol, Ramon
Azo dyes are largely used in many industries and discharged in large volumes of their effluents into the aquatic environment giving rise to non-esthetic pollution and health-risk problems. Due to the high stability of azo dyes in ambient conditions, they cannot be abated in conventional wastewater treatment plants. Over the last fifteen years, the decontamination of dyeing effluents by persulfate (PS)-based advanced oxidation processes (AOPs) has received a great attention. In these methods, PS is activated to be decomposed into sulfate radical anion (SO4•−), which is further partially hydrolyzed to hydroxyl radical (•OH). Superoxide ion (O2•−) and singlet oxygen (1O2) can also be produced as oxidants. This review summarizes the results reported for the discoloration and mineralization of synthetic and real waters contaminated with azo dyes covering up to November 2023. PS activation with iron, non-iron transition metals, and carbonaceous materials catalysts, heat, UVC light, photocatalysis, photodegradation with iron, electrochemical and related processes, microwaves, ozonation, ultrasounds, and other processes is detailed and analyzed. The principles and characteristics of each method are explained with special attention to the operating variables, the different oxidizing species generated yielding radical and non-radical mechanisms, the addition of inorganic anions and natural organic matter, the aqueous matrix, and the by-products identified. Finally, the overall loss of toxicity or partial detoxification of treated azo dye solutions during the PS-based AOPs is discussed.
The recent development of innovative photoelectro-Fenton processes for the effective and cost-effective remediation of organic pollutants in waters
(Elsevier Ltd., 2024-10-08) Brillas, Enric; Peralta-Hernández, Juan Manuel
Wastewaters with toxic and recalcitrant organic contaminants are poorly remediated in conventional wastewater treatment plants. So, powerful processes need to be developed to destroy such organic pollutants to preserve the quality of the aquatic environment. This critical and comprehensive review presents the recent innovative development of photoelectro-Fenton (PEF) covering the period 2019–September 2024. This emerging photo-assisted Fenton-based electrochemical advanced oxidation process (EAOP) is an efficient and cost-effective treatment for water remediation. It possesses a great oxidation power because the in-situ generated hydroxyl radical as oxidant is combined with the photolysis of the organic by-products under UV or sunlight irradiation. The review is initiated by a brief description of the characteristics of the PEF process to stand out in the role of generated oxidizing agents. Further, the homogeneous PEF. PEF-like, solar PEF (SPEF), and SPEF-like processes with iron catalysts are discussed, taking examples of their application to the removal and mineralization of solutions of industrial chemicals, herbicides, dyes, pharmaceuticals, and direct real wastewaters. Novel heterogeneous PEF treatments of such pollutants with solid iron catalysts or functionalized cathodes are analyzed. Finally, novel hybrid processes including PEF/photocatalysis and PEF/photoelectrocatalysis, followed by novel and potent sequential processes like electrocoagulation-PEF and persulfate-PEF, are discussed. Throughout the manuscript, special attention was made to the total operating cost of PEF, which is more expensive than conventional electro-Fenton due to the high electric cost of the UV lamp, pointing to consider the much more cost-effective SPEF as a preferable alternative in practice.
Eliminació d'antibiòtics de matrius aquoses sintètiques i reals mitjançant processos d'oxidació avançada basats en peroximonosulfat. Una revisió dels desenvolupaments recents
(Elsevier Ltd., 2024-01-12) Brillas, Enric; Peralta-Hernández, J.M.
The widespread use of antibiotics for the treatment of bacteriological diseases causes their accumulation at low concentrations in natural waters. This gives health risks to animals and humans since it can increase the damage of the beneficial bacteria, the control of infectious diseases, and the resistance to bacterial infection. Potent oxidation methods are required to remove these pollutants from water because of their inefficient abatement in municipal wastewater treatment plants. Over the last three years in the period 2021–September 2023, powerful peroxymonosulfate (PMS)-based advanced oxidation processes (AOPs) have been developed to guaranty the effective removal of antibiotics in synthetic and real waters and wastewater. This review presents a comprehensive analysis of the different procedures proposed to activate PMS-producing strong oxidizing agents like sulfate radical (SO4•−), hydroxyl radical (•OH, radical superoxide ion (O2•−), and non-radical singlet oxygen (1O2) at different proportions depending on the experimental conditions. Iron, non-iron transition metals, biochar, and carbonaceous materials catalytic, UVC, photocatalytic, thermal, electrochemical, and other processes for PMS activation are summarized. The fundamentals and characteristics of these procedures are detailed remarking on their oxidation power to remove antibiotics, the influence of operating variables, the production and detection of radical and non-radical oxidizing agents, the effect of added inorganic anions, natural organic matter, and aqueous matrix, and the identification of by-products formed. Finally, the theoretical and experimental analysis of the change of solution toxicity during the PMS-based AOPs are described.
Density Functional Theory (DFT) and Time-Dependent DFT (TDDFT) Studies of Porphyrin Adsorption on Graphene: Insights on the Effect of Substituents and Central Metal on Adsorption Energies
(Wiley, 2024-12-05) Gara, Rayene; Morales García, Ángel; Arfaoui, Youssef; Illas i Riera, Francesc
Combining metalloporphyrins (MPr) and graphene constitutes key composites in the development of photovoltaic devices. Here, we focus on the analysis of the properties of metalloporphyrins/graphene systems by means of the density functional theory (DFT) and its time-dependent (TDDFT) version, focusing on the ground and singlet excited states. Our benchmark analysis concludes that ωB97XD density functional combined with 6-31G(d)/Def2-TZVP basis set is a better-suited method for simulating accurate MPr adsorption on graphene. It is shown that a reduced atomic model where the external organic shell of the structure is removed provides the same resulting optoelectronic properties of the original model, constituting an important speed-up of the calculations when studying porphyrins-derived molecules. We observe that ZnPr provides the highest light harvesting efficiency (LHE) value. In addition, we find out that the adsorption energy increases monotonically with the size of the graphene flake and the highest stability involves the use of graphene comprising above 500 atoms. Besides, CdPr and HgPr keep their properties as photosensitizers when they are bonded to graphene and show promising values in terms of LHE emerging as suitable solar energy harvesters.

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