1. Iron phosphide electrocatalyst for renewable production of value-added productsTakwa Chouki, Manel Machreki, Iwona A. Rutkowska, Beata Rytelewska, Pawel Jozef Kulesza, Georgi Tyuliev, Moussab Harb, Luis Miguel Azofra, Saim Emin, 2022, published scientific conference contribution abstract (invited lecture) Abstract: The electrochemical reduction reaction of the nitrate ion (NO3) to valuable ammonia (NH3) is a promising green approach. Herein, we report for the the electrocatalytic reduction of NO3 using different phases of iron phosphide. Particularly, FeP and Fe2P phases were successfully demonstrated as efficient catalysts for NH3 generation. The Fe2P catalyst exhibits the highest Faradaic efficiency (96%) for NH3 generation with a yield (0.25 mmol h−1 cm-−2) at −0.55 V vs. reversible hydrogen electrode (RHE). The recycling tests confirmed that Fe2P and FeP catalysts exhibit excellent stability during the NO3 reduction at −0.37 V vs. RHE. These results indicate that the Fe2P phase exhibits excellent performance to be deployed as an efficient noble metal-free catalyst for NH3 generation. In addition to NO3 reduction the iron phosphide phases were used in electrocatalytic H2 generation using water electrolysis. The electrocatalytic activities of heat-treated Fe2P−450°C, Fe3P−500°C, and Fe2P/FeP−500°C catalysts were studied for hydrogen evolution reaction (HER) in 0.5 M H2SO4. The lowest electrode potential of 110 mV vs. a reversible hydrogen electrode (RHE) at 10 mA cm−2 was achieved with a mixed Fe2P/FeP−500°C catalyst.
Keywords: electrochemical reduction, nitrate reduction, iron phosphide catalyst, NH3 generation
Published in RUNG: 10.01.2025; Views: 331; Downloads: 2
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4. Characterization of the particle size distribution, mineralogy, and Fe mode of occurrence of dust-emitting sediments from the Mojave Desert, California, USAAdolfo Gonzalez-Romero, Cristina González-Flórez, Agnesh Panta, Jesús Yus-Díez, Patricia Córdoba, Andrés Alastuey, Natalia Jiménez-Moreno, Melani Hernández-Chiriboga, Konrad Kandler, Martina Klose, 2024, original scientific article Abstract: Abstract. Constraining dust models to understand and quantify the effect of dust upon climate and ecosystems requires comprehensive analyses of the physiochemical properties of dust-emitting sediments in arid regions. Building upon previous studies in the Moroccan Sahara and Iceland, we analyse a diverse set of crusts and aeolian ripples (n=55) from various potential dust-emitting basins within the Mojave Desert, California, USA. Our focus is on characterizing the particle size distribution (PSD), mineralogy, aggregation/cohesion state, and Fe mode of occurrence. Our results show differences in fully and minimally dispersed PSDs, with crusts exhibiting average median diameters of 92 and 37 µm, respectively, compared to aeolian ripples with 226 and 213 µm, respectively. Mineralogical analyses unveiled strong variations between crusts and ripples, with crusts being enriched in phyllosilicates (24 % vs. 7.8 %), carbonates (6.6 % vs. 1.1 %), Na salts (7.3 % vs. 1.1 %), and zeolites (1.2 % and 0.12 %) and ripples being enriched in feldspars (48 % vs. 37 %), quartz (32 % vs. 16 %), and gypsum (4.7 % vs. 3.1 %). The size fractions from crust sediments display a homogeneous mineralogy, whereas those of aeolian ripples display more heterogeneity, mostly due to different particle aggregation. Bulk Fe content analyses indicate higher concentrations in crusts (3.0 ± 1.3 wt %) compared to ripples (1.9 ± 1.1 wt %), with similar proportions in their Fe mode of occurrence: nano-sized Fe oxides and readily exchangeable Fe represent ∼1.6 %, hematite and goethite ∼15 %, magnetite/maghemite ∼2.0 %, and structural Fe in silicates ∼80 % of the total Fe. We identified segregation patterns in the PSD and mineralogy differences in Na salt content within the Mojave basins, which can be explained by sediment transportation dynamics and precipitates due to groundwater table fluctuations described in previous studies in the region. Mojave Desert crusts show similarities with previously sampled crusts in the Moroccan Sahara in terms of the PSD and readily exchangeable Fe yet exhibit substantial differences in mineralogical composition, which should significantly influence the characteristic of the emitted dust particles.
Keywords: mineral dust, iron oxides
Published in RUNG: 29.11.2024; Views: 451; Downloads: 4
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5. Environmental priorities in the circular economy : examples from iron-based technologiesAndreea Oarga-Mulec, Uroš Luin, Keith R. Skene, Matjaž Valant, 2024, published scientific conference contribution Abstract: The circular economy (CE) framework is crucial for promoting resource efficiency and minimizing waste, but it cannot achieve its sustainability goals alone. To achieve a truly sustainable future, broader social, environmental and economic aspects need to be taken into account. Rather than separating biological and technological cycles, as the CE principles are depicted in the Ellen MacArthur Foundation’s butterfly diagram (EMF, 2017), we propose an integrated approach that prioritises environmental aspects and includes a conceptual framework, socio-economic changes and implementation processes. It is crucial to re-evaluate the environmental aspects and strengthen their importance within the CE framework. Within this concept we present the case of iron, the most widely used metal, widely available compared to others and has been an essential part of societal development for more than 5,000 years. With its abundance, safety and electrochemical properties, iron is an ideal material for low-carbon energy technologies. We discuss how advanced iron-based technologies have a high potential to be successfully integrated into the CE, we evaluate different electrochemical energy storage systems and present advances in thermochemical Fe-Cl cycles for hydrogen production. An innovative thermal system for hydrogen production based on the thermochemical Fe-Cl cycle was evaluated in a life cycle assessment (LCA) study and shows the importance of choosing sustainable energy sources to minimise environmental impact. Sustainable production methods for iron are also analysed to demonstrate their potential to reduce the carbon footprint of the iron and steel industry. Finally, efforts should focus on minimising environmental impact and optimising resource recovery.
Keywords: circular economy, resource efficiency, sustainability, iron, hydrogen
Published in RUNG: 25.11.2024; Views: 551; Downloads: 0
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6. First utilization of magnetically-assisted photocatalytic iron ▫$oxide-TiO_2$▫ nanocomposites for the degradation of the problematic antibiotic ciprofloxacin in an aqueous environmentJosip Radić, Gregor Žerjav, Lucija Jurko, Perica Bošković, Lidija Fras Zemljič, Alenka Vesel, Andraž Mavrič, Martina Gudelj, Olivija Plohl, 2024, original scientific article Abstract: The emergence of antimicrobial resistance due to antibiotics in the environment presents significant public health, economic, and societal risks. This study addresses the need for effective strategies to reduce antibiotic residues, focusing on ciprofloxacin degradation. Magnetic iron oxide nanoparticles (IO NPs), approximately 13 nm in size, were synthesized and functionalized with branched polyethyleneimine (bPEI) to obtain a positive charge. These IO-bPEI NPs were combined with negatively charged titanium dioxide NPs (TiO2@CA) to form magnetically photocatalytic IO-TiO2 nanocomposites. Characterization techniques, including X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), infrared spectroscopy (IR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), electrokinetic measurements, and a vibrating sample magnetometer (VSM), confirmed the successful formation and properties of the nanocomposites. The nanocomposites exhibited a high specific surface area, reduced mobility of photogenerated charge carriers, and enhanced photocatalytic properties. Testing the photocatalytic potential of IO-TiO2 with ciprofloxacin in water under UV-B light achieved up to 70% degradation in 150 min, with a degradation rate of 0.0063 min−1. The nanocomposite was magnetically removed after photocatalysis and successfully regenerated for reuse. These findings highlight the potential of IO-TiO2 nanocomposites for reducing ciprofloxacin levels in wastewater, helping curb antibiotic resistance.
Keywords: photocatalytic degradation, magnetic iron oxide-TiO2 nanocomposites, hetero-agglomeration, multifunctionality, antibiotic ciprofloxacin, antimicrobial resistance
Published in RUNG: 09.09.2024; Views: 864; Downloads: 6
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7. Back to the future with emerging iron technologiesAndreea Oarga-Mulec, Uroš Luin, Matjaž Valant, 2024, review article Abstract: Here is a comprehensive overview of iron's potential in low-carbon energy technologies, exploring applications like metal fuel combustion, iron-based batteries, and energy-carrier cycles, as well as sustainable approaches for production and recycling with a focus on reducing environmental impact. Iron, with its abundance, safety, and electrochemical characteristics, is a promising material to contribute to a decarbonized future. This paper discusses the advancements and challenges in iron-based energy storage technologies and sustainable iron production methods. Various innovative approaches are explored as energy storage solutions based on iron, like advancements in thermochemical Fe–Cl cycles highlight the potential of iron chloride electrochemical cycles for long-term high-capacity energy storage technology. Additionally, the utilization of iron as a circular fuel in industrial processes demonstrates its potential in large-scale thermal energy generation. Sustainable iron production methods, such as electrolysis of iron chloride or oxide and deep eutectic solvent extraction, are investigated to reduce the carbon footprint in the iron and steel industry. These findings also show the importance of policy and technology improvements that are vital for the widespread use and recycling of iron-based tech, stressing the need for collaboration toward a sustainable future.
Keywords: iron's potential, low-carbon energy technologies
Published in RUNG: 02.07.2024; Views: 1673; Downloads: 8
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8. Chemistry of the iron-chlorine thermochemical cycle for hydrogen production utilizing industrial waste heatMatjaž Valant, Uroš Luin, 2024, original scientific article Abstract: This research presents an inventive thermochemical cycle that utilizes a reaction between iron and HCl acid for hydrogen production. The reaction occurs spontaneously at room temperature, yielding hydrogen and a FeCl2 solution as a by-product. Exploring the thermal decomposition of the FeCl2 by-product revealed that, at conditions suitable for utilization of low-temperature industrial waste heat (250 °C), chlorine gas formation can be circumvented. Instead, the resulting by-product is HCl, which is readily soluble in water, facilitating direct reuse in subsequent cycles. The utilization of low-temperature industrial heat not only optimizes resource utilization and reduces operational costs but also aligns with environmentally sustainable production processes. From the kinetic studies the activation energy was calculated to be 45 kJ/mol and kinetics curves were constructed. They showed significant kinetics at room temperature and above but rapid decrease towards lower temperatures. This is important to consider during real-scale technology optimization. The theoretical overall energy efficiency of the cycle, with 100% and 70% heat recuperation, was calculated at 68.8% and 44.8%, respectively. In practical implementation, considering the efficiency of DRI iron reduction technology and free waste heat utilization, the cycle achieved a 41.7% efficiency. Beyond its energy storage capabilities, the Iron-chlorine cycle addresses safety concerns associated with large-scale hydrogen storage, eliminating self-discharge, reducing land usage, and employing cost-effective storage materials. This technology not only facilitates seasonal energy storage but also establishes solid-state energy reserves, making it suitable for balancing grid demands during winter months using excess renewable energy accumulated in the summer.
Keywords: chemical cycles, hydrogen production, thermal decomposition, reaction kinetics, iron, chlorine
Published in RUNG: 12.01.2024; Views: 2373; Downloads: 44
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10. Where is iron? : depth binding profiles in Chelex resin hydrogels using diffusive gradients in thin films - beam deflection spectrometry methodDorota Korte, Hanna Budasheva, Mohanachandran Nair Sindhu Swapna, Sankaranarayana Iyer Sankararaman, Arne Bratkič, 2023, published scientific conference contribution abstract Keywords: iron, Chelex resin, diffusive gradients, thin films, beam deflection spectrometry
Published in RUNG: 09.01.2024; Views: 1665; Downloads: 3
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