22 research outputs found
NiO Nanoparticles as Electrocatalyst for Nitrates Reduction
No full textThe introduction of the Haber-Bosch (HB) process in the early twentieth century enabled the large-scale production of NH3, swiftly becoming one of the most crucial chemical products worldwide due to its extensive application in agriculture as a fertilizer. Moreover, NH3 has recently garnered significant interest as a potential renewable energy storage system, given its capacity to serve as a source of hydrogen.
However, the Haber-Bosch process, reliant on atmospheric nitrogen and fossil fuel, requires H2 for NH3 production, as well as high process temperature and pressure, contributing to approximately 1.6% of the annual global CO2 emissions. A promising alternative lies in the electrochemical nitrogen reduction reaction (E-NRR) to synthesize NH3 under ambient conditions. However, to date, this process has a limited yield production and a low selectivity due to the high stability of the N2 molecule and the presence of parasitic reactions, primarily leading to water (solvent) conversion into hydrogen.
A more recent focus has emerged towards the reduction of NO3‒, as it can be more easily converted into NH3 with a significant Faradaic efficiency (FE) and high yield. Moreover, owing to the prevalent use of nitrogen-based fertilizers, this process possesses a significant real-case application towards wastewater treatment were high NO3‒ levels have often been detected.
This study presents the utilization of a nanostructured NiO electrocatalyst, prepared by precipitation in aqueous medium and calcinated at 600 °C, for the reduction of NO3‒ into NH3, achieving an average FE of 36% and a production rate ranging from 28 to 107 μg h cm‒2, depending on the initial NO3‒ concentration. The experiments were conducted in a H-type cell, utilizing three different concentrations of KNO3 (NO3‒ source), i.e. 0.1, 0.05, and 0.008 M. A second investigated experimental parameter was the concentrations of the supporting electrolyte (i.e., K2SO4), that was used at 0.4, 0.45, and 0.492 M. The tests were conducted under an applied potential (E) of ‒1.4 V vs. Ag/AgCl for a duration of 2 h.
In this contribution, we will show the main outcomes derived from this newly explored electrocatalysts, highlighting the main structure-performance correlations
Nitrates Reduction using NiO Nanoparticles as Electrocatalyst
No full textThe introduction of the Haber-Bosch (HB) process in the early twentieth century revolutionized the NH3 chemical production, contributing in a particularly significant way in the agricultural sector, given the widespread use of this product as a synthetic fertilizer. Its significance further extends to recent explorations in renewable energy, with NH3 emerging as a potential storage medium for hydrogen.
Despite its extensive adoption, the Haber-Bosch process poses environmental challenges.
Reliance on fossil fuels, coupled with elevated temperatures and pressures required to catalyse the synthesis reaction, leads to the production of a quantity of CO2 equal to approximately 1.6% of annual global production.
A promising alternative lies in the electrochemical nitrogen reduction reaction (E-NRR) to synthesize NH3 under ambient conditions. However, to date, this process has a limited yield production and a low selectivity due to the high stability of the N2 molecule and the presence of parasitic reactions, primarily leading to water (solvent) conversion into hydrogen.
A more recent focus has emerged towards the reduction of NO3‒, as it can be more easily converted into NH3 with a significant Faradaic efficiency (FE) and high yield. Moreover, owing to the prevalent use of nitrogen-based fertilizers, this process possesses a significant real-case application towards wastewater treatment were high NO3‒ levels have often been detected.
This study presents the utilization of a nanostructured NiO electrocatalyst, prepared by precipitation in aqueous medium and calcinated at 600 °C, for the reduction of NO3‒ into NH3, achieving an average FE of 36% and a production rate ranging from 28 to 107 μg h cm‒2, depending on the initial NO3‒ concentration. The experiments were conducted in a H-type cell, utilizing three different concentrations of KNO3 (NO3‒ source), i.e. 0.1, 0.05, and 0.008 M. A second investigated experimental parameter was the concentrations of the supporting electrolyte (i.e., K2SO4), that was used at 0.4, 0.45, and 0.492 M. The tests were conducted under an applied potential (E) of ‒1.4 V vs. Ag/AgCl for a duration of 2 h.
In this contribution, we will show the main outcomes derived from this newly explored electrocatalysts, highlighting the main structure-performance correlations
Transient evoked otoacoustic emission latency and estimates of cochlear tuning in preterm neonates
No full textThe latency of transient evoked otoacoustic emissions has been evaluated in a sample of 58 ears from 34 preterm neonates, to understand if the estimates of cochlear tuning based on the otoacoustic emission latency show signs of developmental changes. A previous study on the same otoacoustic emissions analyzed here [Tognola et al. (2005). "Cochlear maturation and otoacoustic emissions in preterm infants: A time-frequency approach,"Hear. Res., 199, 71-80] reported indeed a significant change in the otoacoustic emission latency with postconception age. This last result, which would imply a significant decrease of tuning, was partially biased by the presence of spontaneous emissions. In this study, the same neonate data are reanalyzed using a novel time-frequency algorithm, less sensitive to spontaneous emissions. Asymmetry between right and left ears has been found, with the left ears showing no significant change, whereas in the right ears and in the 1.5-2.5 kHz frequency range only, a slow decrease of latency with postconception age (0.1-0.2 ms/week) was observed. The correspondent tuning estimates based on latency decrease by 0.4-0.5/week. Significant differences between neonate and adult latency were confirmed, which could be either cochlear or middle ear in nature. These findings are compared to previous studies on distortion product suppression tuning curves in preterm neonates. (C) 2008 Acoustical Society of America. [DOI: 10.1121/1.2977737
Alpine and Northern European arctic charr (Salvelinus alpinus) populations analyzed by means of mitochondrial control region sequences and nuclear AFLP markers.
No full textChallenges and Advancements in Sustainable Ammonia Production via Electrochemical Nitrogen and Nitrate Reduction
No full textAmmonia (NH3) is a cornerstone of modern society, serving as the basis for all nitrogen fertilizers, which sustain nearly half of the world’s population. Furthermore, thanks to its high energy density (4.32 kWh L−1 for liquid NH3) and ease of liquefaction, ammonia is emerging as a potential renewable energy carrier and fuel for decarbonization efforts. However, current NH3 production relies heavily on the Haber-Bosch process (HBP), which is highly energy-intensive, consuming 1–2% of global fossil fuels and accounting for approximately 2% of worldwide CO2 emissions. This underscores the urgent need for sustainable and decentralized NH3 synthesis technologies.
Electrochemical nitrogen and nitrate reduction reactions (E-NRR and E-NO3RR) have garnered significant attention as greener alternatives to the HBP. These processes allow for renewable electricity utilization and on-site, on-demand ammonia production. Additionally, nitrate (NO3−), a widespread pollutant in groundwater due to its high solubility, can be converted into valuable NH3 via E-NO3RR. However, both E-NRR and E-NO3RR face challenges and low production rates, insufficient Faradaic efficiencies and high overpotentials represent an intriguing challenge. The main components contributing to the overall system performance are the catalyst, the electrolyte and the reactor and thus their full comprehension is crucial to boost E-NRR and E-NO3RR technologies. Despite advancements, reproducibility issues and scaling challenges persist.
In conclusion, E-NRR and E-NO3RR offer promising pathways for sustainable ammonia production, with significant potential for scalability and integration with renewable energy. Continued research into advanced catalysts and electrolyte formulations is essential to overcoming current limitations and achieving the full potential of these technologies
Urban sprawl facilitates invasions of exotic plants across multiple spatial scales
No full textExotic plant invasions are considered one of the major threats to biodiversity causing important impacts at the population, community, and ecosystem levels. Understanding the drivers of plant invasions across multiple spatial and temporal scales often requires a landscape approach. The effect of landscape composition on biological invasion has been extensively studied, whereas landscape configuration effects were seldom considered or the analyses were limited to single species. Here, we aimed to analyze how the expansion of urban and agricultural areas can affect exotic species richness (both neophytes and archaeophytes) at three spatial scales, namely regional (scale: 37.5 km2), landscape (scale: 7.1 km2) and local (scale: 100 m2). We considered the possible contribution of urban and agricultural areas both in terms of composition (i.e. habitat cover) and configuration (i.e. shape complexity of patches). First, we found that increasing urbanization coupled with high shape complexity of urban elements were major drivers of both neophyte and archaeophyte invasions across heterogeneous landscapes. In particular, shape complexity seemed to be a key driver of plant invasions at large spatial scale, whereas the type of recipient habitat and urban cover determined the exotic success at the patch level. Second, archaeophytes were also affected by agriculture land use, i.e. agricultural patches shape complexity increased their spread at both regional and landscape scales. High shape complexity of highly disturbed habitats is expected to increase the exchange surface that exotic plant use to spread their propagules across the landscape mosaics. Our findings suggest that urban planning aimed at curbing urban fragmentation by both reducing shape complexity and diffuse urban sprawl might greatly improve the resistance of landscapes to biological invasions
Tailoring NiO defectivity to boost the electrocatalytic activity toward nitrate reduction into ammonia
No full textAmmonia is vital for global agriculture, yet its conventional synthesis via the Haber–Bosch process is energy-intensive and environmentally burdensome, contributing ∼2% of global CO2 emissions. Simultaneously, excessive use of ammonia-based fertilizers has led to nitrate pollution in water systems. Electrochemical nitrate reduction (E-NO3RR) offers a dual solution: mitigating nitrate contamination while enabling decentralized, sustainable ammonia production. Here, we explore nickel oxide (NiO) nanoparticles as efficient, low-cost electrocatalysts for E-NO3RR, capitalizing on their earth abundance and inherent ability to suppress competing hydrogen evolution. NiO is synthesized via a scalable precipitation method using different ethanol/water solvent ratios to modulate defect density, porosity, and crystallinity. Materials-related differences are probed by thermal, structural, and spectroscopy methods. Electrochemical tests reveal that increasing ethanol content during synthesis enhances defectiveness, correlating with improved Faradaic efficiency and ammonia production rates. This work underscores the critical role of synthetic parameters in tailoring catalytic performance and positions defect-engineered NiO as a promising platform for green ammonia generation via nitrate reduction
Analysis of time-frequency fine structure of transiently evoked otoacoustic emissions to study the effects of exposure to GSM radio frequency fields
No full textEnhancing green ammonia production from nitrogenous species electroreduction through electrolyte optimization
No full textThe growing risk of a potential energy crisis and escalating environmental challenges highlight the inminet need for research focused on alternative, sustainable energy sources capable of substituting fossil fuels. Ammonia (NH3) has been extensively produced and utilised as a fertiliser for over a century. Currently, due to its significant hydrogen content (17.6% wt), high energy density (4.32 kW h L−1 for liquid NH3), easy liquefaction for handling, storage and transportation, it is gaining momentum as a promising alternative renewable energy carrier and storage intermediate for global use in the future. NH3 is produced via the well-established Haber-Bosch process (HBP), which is well known for its high energy demands that consume 1-2% of fossil fuels worldwide, contributing to the greenhouse effect by releasing the equivalent of ca. 2% of total CO2 global emissions. Therefore, the development of greener and more sustainable technologies to replace the century-old Haber-Bosch process is imperative. The electrochemical reduction reaction of nitrogenous spices (E-NRR) is a suitable technology widely recognised as an alternative option to the traditional HBP. E-NRR offers several key benefits:: (i) it is thermodynamically predicted to be more energy efficient than the HBP by 20%; (ii) it permits the elimination of fossil fuels as H2 source; (iii) it can be integrated with renewables energy resources (e.g. solar panel, windmill, etc.); (iv) it is scalable and can lead to on-demand & on-site NH3 production. Thus far, research on E-NRR has mostly focused on the electrocatalyst; however, it is well known that the electrolyte plays a crucial role, potentially having an impact of several orders of magnitude on the process outcome, particularly affecting selectivity and efficiency. In E-NRR the optimal electrolyte should enhance N2 solubility, limit the H+ to minimize the parasitic hydrogen evolution reaction (HER), maintain the catalyst stability, and thus improve the Faradic efficiency (FE). The types of proton donors, solvents and additives, such as alkali metal ions, are critical in enhancing the selectivity of the E-NRR process.
In this context, the present work aims to explore the use of glycerol-water mixture in different proportions as a solvent in the electrolyte to study the potential beneficial effect of glycerol in terms of N2 solubility increment and HER mitigation. Furthermore, it has been demonstrated that Nafion membranes, usually used as separators on E-NRR systems, represent an important source of NH3 impurities, leading to false positives or overestimation of the NH3 production. Taking that into account, a set of experiments has been performed to elucidate the membrane-ammonia interactions and quantify the impurities in our system
