Amount Of NO Research Articles

Accelerating electron transfer reduces CH4 and CO2 emissions in paddy soil.

As an accelerated electron transfer device, the influence of microbial electrochemical snorkel (MES) on soil greenhouse gas production remains unclear. Electron transport is the key to methane production and denitrification. We found that the N2O amount of the MES treatment was comparable to the control however the cumulative CO2 and CH4 emissions were reduced by 50% and 41%, respectively. The content of Fe2+ in MES treatment increased by 31%, which promoted the electron competition of iron reduction to methanogenesis. Furthermore, the competition among iron-reducing, nitrifying and denitrifying bacteria reduced the abundance of methanogens by 19-20%. Additionally, the MES treatment decreased the abundance of genes associated with hydrogen methanogenesis pathway by 6-19%, and inhibited the further conversion of acetyl-CoA into CH4 for acetoclastic methanogenesis. This study reveals effects of accelerating electron transfer on greenhouse gas emission, and provides a novel strategy for reducing greenhouse gas emissions in paddy soil.

Fabrication and application of ZIF-8 derived In2O3-ZnO nanocomposites for ultra-sensitive NO2 sensing under UV irradiation at room temperature

Nitrogen oxide (NO2) is common by-products of industrial production, posing significant health risks to workers. Therefore, real-time monitoring of NO2 is crucial. In this study, innovative In2O3-ZnO nano-materials were prepared by combining In2O3 with ZIF-8 via electrospinning, for detecting trace amounts of NO2 at room temperature (RT). Compared to pure In2O3, the In2O3-ZnO nano-materials (V2) with a 10 % weight ratio of ZIF-8 exhibited a significantly higher response (389.99) and a faster response time (16.9 s) to NO2 under ultraviolet (UV) irradiation at RT. The superior gas sensing performance of the V2 nano-materials is attributed to the formation of n-n heterojunctions, enhanced optical absorption, increased oxygen vacancy ratio, and excellent dispersion among the nano-materials. The results demonstrate that V2 nano-materials can detect NO2 at parts-per-billion (ppb) levels at RT, making them suitable for monitoring trace amounts of NO2 in open environments. Furthermore, a portable real-time NO2 monitoring device was constructed using V2 as the sensing material, an LM358-based amplifier circuit for data acquisition, an STM32F103C8T6 microcontroller as the main control unit, and a buzzer as an alarm device. Compared to devices using a helical Ni-Cr wire as an indirect heat source, this integrated NO2 detection device offers real-time alarms with lower energy consumption. This application not only enhances worker health and safety in industrial environments but also demonstrates higher energy efficiency in practical application.

Comparison of Nitrous Oxide Consumption of Paddy Soils Developed from Three Parent Materials in Subtropical China

Paddy soils developed from various parent materials are widely distributed in the subtropical region in China and have a non-negligible but unclear potential to consume nitrous oxide (N2O) due to long-term flooding. This study selected three of the most common paddy soils in subtropical China, developing from quaternary red soil (R), lake sediment sand (S), and alluvial soil (C), to study their total N2O consumption and total nitrogen (N2) production using N2-free microcosm experiments. These paddy soils were treated with N2O addition (N2O treatment) or helium (He) addition (CK treatment) and incubated under flooding and anoxic conditions. The results showed that three alluvial soils (C1, C2, and C3) consumed over 99.93% of the N2O accumulated in the soil profile, significantly higher than R and S soils (p < 0.05). And the N2 production in three C soils was also significantly higher than other soils, accounting for 81.61% of the total N2O consumption. The main soil factors affecting N2O consumption in C, S, and R soils were soil clay content (p < 0.05), soil sand content (R2 = 0.95, p < 0.001), and soil available potassium (AK) (p < 0.01), respectively. These results indicate flooding paddy soils, no matter the parent materials developed, could consume extremely large amount of N2O produced in soil profiles.

Investigating the Effect of Ammonia Addition on the Performance of a Heavy-Duty Natural Gas Spark Ignition Engine Operated at Stoichiometric Conditions

Abstract Due to the pressing issue of global warming, there has been a significant focus on zero- and low-carbon fuels globally. Among hydrocarbon fuels, methane is widely used in spark ignition engines due to its abundance and relatively low carbon footprint. However, to further reduce carbon emissions, interest is growing in the use of ammonia, a zero-carbon fuel, as a partial replacement for methane. Consequently, it is crucial to investigate the impact of ammonia addition on the performance of natural gas spark ignition engines. A key challenge in studying ammonia-methane engines is that the introduction of ammonia alters the formation mechanisms of nitrogen-based pollutants, resulting in the coupling of fuel-borne and air-borne nitrogen pollutants. As a result, research on the nitrogen-based emissions of ammonia-methane engines has been limited. This study addresses this issue by differentiating between atmospheric nitrogen and fuel nitrogen elements, effectively decoupling fuel-borne and air-borne nitrogen pollutants. This approach provides valuable insights into the effects of ammonia addition on the nitrogen-based pollutant characteristics of natural gas engines. The results indicate that ammonia addition introduces N2O, a species absent in pure methane engines. The N2O primarily originates from cold wall regions and the partial oxidation of ammonia released from engine crevices during the late oxidation process. Although NO remains the dominant nitrogen-based pollutant and the amount of N2O is small, the significant greenhouse gas potential of N2O warrants further attention. Furthermore, while ammonia addition increases the NO concentration in the burning zone, it slightly reduces the NO concentration at chemical equilibrium under stoichiometric conditions. As a result, engines operating with an ammonia energy substitution ratio of 0.4 exhibit lower NOx emissions compared to those fueled solely by methane. These findings underscore the need for further research into the combustion and emission characteristics of ammonia-methane spark ignition engines.

Інтенсивність нітрозо-оксидативних процесів у ротовій рідині дітей з поєднанням латентного залізо- та легкого йододефіциту

Proper supply of bioelements that participate in physiological processes is especially important in childhood, because it significantly affects for the formation of the hormonal profile. The prevalence of dental pathology among schoolchildren reflects the priority of early diagnosis and thorough prevention of pathological processes. In order to find out the risks of dental health disorders, the intensity of nitroso-oxidative processes in the oral fluid of children (boys and girls aged 6-11 and young men and girls aged 12-18) with combined latent iron and mild iodine deficiency was studied and in conditions of sufficient supply of trace elements (control group). As a result of the study, the activation of the peroxidation processes of proteins (the level of products of oxidative modification of proteins increases by 87.3% - 3.3 times) and lipids (the content of diene conjugates increases by 62.7% - 12.4 times) in case of imbalance of antioxidant protection of oral fluid (inhibition of SOD by 20.4-30.7%, activation of glutathione peroxidase by 92.0-93.3%) compared to data in healthy teenagers. The development of iron and iodine deficiency is accompanied by an 8.3-fold increase in NO2 - content, a 3.3-fold increase in the amount of NO2 - and NO3 - in the oral fluid of boys, and a 2.5-11.4-fold increase in the concentration of peroxynitrite in all schoolchildren compared to controls. An increase in H2S content in the oral fluid was also found in girls (by 25.6% compared to the values of the control group). The level of oxidative processes is higher in younger schoolchildren (ages 6-11). With age, the intensity of oxidative stress decreases, but changes in the NO metabolism system increase, especially for girls (cytotoxic peroxynitrite and H2S accumulate in the oral fluid). Therefore, it is possible to assert a high probability of the development of nitroso-oxidative stress in the conditions of a combination of iron and iodine deficiency already at the stage of preclinical changes, which can increase the risks of developing dental pathology.

Comparison of the Transport of Reactive Nitrogen Plasma Species into Water Bulk vs. Aerosolized Microdroplets

This work presents the experimental study of the transport of typical air plasma long-lived reactive nitrogen species (RNS: HNO2, NO2, and NO) into deionized water and compares them with the most typical reactive oxygen species (ROS: H2O2 and O3). RONS are generated either by external sources or by a hybrid streamer-transient spark plasma discharge, in contact with bulk water or aerosol of charged electrospray (ES) or non-charged nebulized microdroplets with a large gas/plasma-water interface. It was found that NO’s contribution to NO2¯ ion formation was negligible, NO2 contributed to about 10%, while the dominant contributor to NO2¯ ion formation in water was gaseous HNO2. A higher transport efficiency of O3, and a much higher formation efficiency of NO2¯ from gaseous NO2 or HNO2 than predicted by Henry’s law was observed, compared to the transport efficiency of H2O2 that corresponds to the expected Henry’s law solvation. The improvement of the transport/formation efficiencies by nebulized and ES microdroplets, where the surface area is significantly enhanced compared to the bulk water, is most evident for the solvation enhancement of the weakly soluble O3. NO2¯ ion formation efficiency was strongly improved in ES microdroplets with respect to bulk water and even to nebulized microdroplets, which is likely due to the charge effect that enhanced the formation of aqueous nitrite NO2¯ ions when NO2 or HNO2 are transported into water. Comparisons of the molar amounts of O3, H2O2, and NO2¯ formed in water by hybrid streamer-transient spark plasma discharge with those obtained with single RONS from the external sources enabled us to estimate approximate concentrations of gaseous concentrations of HNO2, NO2, O3, and H2O2. The medium or highly soluble gaseous HNO2 or H2O2, with a low concentration of < 10 ppm are sufficient to induce the measured aqueous NO2¯ or H2O2 amounts in water. This study contributes to a deeper understanding of the transport mechanism of gaseous plasma RONS into water that can optimize the design of plasma–liquid interaction systems to produce efficient and selected aqueous RONS in water.

Hazardous waste alternative fuels to novel ecological energy: Combustion characteristics and effects on clinker's environmental safety

Due to their detrimental and persistent impacts on the environment, it is imperative to manage and dispose of hazardous wastes (HW) in a secure manner. This study investigates the combustion characteristics and environmental impacts of using HW as alternative fuels in clinker production. The HW categories analyzed include industrial hazardous waste (IHW), medical hazardous waste (MHW), and household hazardous waste (HHW). Specifically, IHW consists mainly of waste mineral oils, waste organic solvents, organic resin wastes, waste residues, and waste coatings. MHW primarily consists of medical plastic products. HHW mainly includes packaging from waste pharmaceuticals, waste pesticides, disinfectants, and waste paints. Compared to traditional pulverized coal, hazardous waste alternative fuel (HWAF) exhibits a lower fixed carbon content, with its heat generation primarily dependent on volatile substances, and a higher ash content, chemically similar to coal ash. The combustion process of HWAF involves three stages: moisture evaporation (0 °C–150 °C), volatile matter combustion (150°C–400 °C), and fixed carbon combustion (400 °C–550 °C). The primary emissions from this process include CO2, CO, trace amounts of SO2, NO2, H2O, and various complex organic compounds such as carboxylic acids, alcohols, ketones, and aldehydes. While HWAF ignites more readily than pulverized coal, it burns more slowly and less completely. The incorporation of combustion by-products into the cement clinker formulation does not interfere with the clinker's hydration processes or reactions. HWAF ensures a reduced heavy metal input rate in the firing system without significantly impacting the heavy metal content in the clinker. Mortar samples produced with this clinker meet the heavy metal leaching standards, affirming the environmental safety of the cement product. Increasing the proportion of HWAF results in a reduction in standard coal consumption and an increase in CO2 reduction, achieving a maximum coal saving of 3.67 kgce/t.cl and a CO2 emission reduction of 10.11 kg/t.cl. This study presents a clean production model for the co-processing of HWAF, effectively transforming waste into valuable resources by using hazardous waste materials as alternative fuels.

Shear-Strained Pd Single-Atom Electrocatalysts for Nitrate Reduction to Ammonia.

Electrochemical nitrate reduction method (NitRR) is a low-carbon, environmentally friendly, and efficient method for synthesizing ammonia, which has received widespread attention in recent years. Copper-based catalysts have a leading edge in nitrate reduction due to their good adsorption of *NO3. However, the formation of active hydrogen (*H) on Cu surfaces is difficult and insufficient, resulting in a large amount of the by-product NO2 -. In this work, Pd single atoms suspended on the interlayer unsaturated bonds of CuO atoms formed due to dislocations (Pd-CuO) were prepared by low temperature treatment, and the Pd single atoms located on the dislocations were subjected to shear stress and the dynamic effect of support formation to promote the conversion of nitrate into ammonia. The catalysis had an ammonia yield of 4.2 mol. gcat -1. h-1, and a Faraday efficiency of 90 % for ammonia production at -0.5 V vs. RHE. Electrochemical in situ characterization and theoretical calculations indicate that the dynamic effects of Pd single atoms and carriers under shear stress obviously promote the production of active hydrogen, reduce the reaction energy barrier of the decision-making step for nitrate conversion to ammonia, further promote ammonia generation.

Gasdiffusionselektroden für die Elektrokatalytische Oxidation von Gasförmigem Ammoniak: Das Überqueren des Thermodynamischen Tals der Stickstoffdreifachbindung

AbstractDa Ammoniak als vielversprechender Wasserstoffträger immer mehr an Interesse gewinnt, wird auch die elektrochemische Ammoniak‐Oxidationsreaktion (AmOR) immer interessanter. Um die Freisetzung von H2 in einer umgekehrten Haber–Bosch‐Reaktion unter Bildung des energetisch günstigeren N2 zu vermeiden, schlagen wir die Oxidation von Ammoniak zu Nitrit (NO2−) vor, das üblicherweise während des Ostwald‐Prozesses gewonnen wird. Wir untersuchten die anodische Oxidation von gasförmigem Ammoniak, der direkt einer Gasdiffusionselektrode (GDE) zugeführt wird, unter Verwendung verschiedener, in ihrer Zusammensetzung unterschiedlicher Multimetallkatalysatoren, die auf Ni‐Schaum abgeschieden sind, bei gleichzeitiger Bildung von H2 an der Kathode. Dadurch wird die H2‐Menge pro Ammoniakmolekül verdoppelt, während gleichzeitig ein niedrigeres Überpotential als bei der Wasserelektrolyse (1,4–1,8 V gegen RHE bei 50 mA cm−2) angelegt wird. Eine Selektivitätsstudie zeigte, dass einige der Katalysatorzusammensetzungen in der Lage waren, erhebliche Mengen an NO2− zu produzieren. Weitere Untersuchungen mit dem vielversprechendsten Katalysator Nif_AlCoCrCuFe, der in eine GDE integriert ist, zeigten eine Faraday‐Effizienz von bis zu 88 % für NO2− an der Anode, gekoppelt mit einer Faraday‐Effizienz von nahezu 100 % für die kathodische H2‐Produktion.

Gas Diffusion Electrodes for Electrocatalytic Oxidation of Gaseous Ammonia: Stepping Over the Nitrogen Energy Canyon.

As ammonia continues to gain more and more interest as a promising hydrogen carrier compound, so does the electrochemical ammonia oxidation reaction (AmOR). To avoid the liberation of H2 in a reverse Haber-Bosch reaction under release of the energetically more favorable N2, we propose the oxidation of ammonia to value-added nitrite (NO2 -), which is usually obtained during the Ostwald process. We investigated the anodic oxidation of gaseous ammonia directly supplied to a gas diffusion electrode (GDE) using a variety of compositionally different multi-metal catalysts coated on Ni foam under the simultaneous formation of H2 at the cathode. This will double the amount of H2 per ammonia molecule while applying a lower overpotential than that required for water electrolysis (1.4-1.8 V vs. RHE at 50 mA ⋅ cm-2). A selectivity study demonstrated that some of the catalyst compositions were able to produce significant amounts of NO2 -, and further investigations using the most promising catalyst composition Nif_AlCoCrCuFe integrated within a GDE demonstrated up to 88 % Faradaic efficiency for NO2 - at the anode coupled to close to 100 % Faradaic efficiency for the cathodic H2 production.

Numerical investigation and optimization of the ammonia/diesel dual fuel engine combustion under high ammonia substitution ratio

This study investigated the effects of initial temperature, equivalence ratio, and diesel injection timing on engine combustion and emission characteristics at high ammonia substitution ratios. Increased compression temperature and pressure significantly reduce ignition delay, enhance combustion speed and efficiency, and decrease N2O and unburned NH3 emissions. A strong correlation exists between the amount of N2O produced and the mass of unburned NH3 when ammonia combustion efficiency is high. The N2O distribution is concentrated near the cylinder walls and the piston top surface, in areas with high concentrations of unburned NH3. As the equivalence ratio increases from 0.6 to 0.75, flame propagation speed and indicated thermal efficiency (ITE) increase, while NOx, N2O, and unburned NH3 emissions decrease. The combustion performance and emissions were optimized by advancing the diesel injection timing and increasing the equivalence ratio to accelerate the combustion speed. This adjustment increases ITE to 47.6 % at an 80 % ammonia energy ratio. Post-optimization results show a reduction in unburned NH3 emissions from 51.7 g/kW·h to 5.9 g/kW·h and a decrease in N2O emissions from 0.930 g/kW·h to 0.370 g/kW·h, culminating in a 60.4 % reduction in greenhouse gas (GHG) emissions.

A Comparison of Regression Methods for Inferring Near‐Surface NO2 With Satellite Data

AbstractNitrogen dioxide (NO2) is an atmospheric pollutant emitted from anthropogenic and natural sources. Human exposure to high NO2 concentrations causes cardiovascular and respiratory illnesses. The Environmental Protection Agency operates ground monitors across the U.S. which take hourly measurements of NO2 concentrations, providing precise measurements for assessing human pollution exposure but with sparse spatial distribution. Satellite‐based instruments capture NO2 amounts through the atmospheric column with global coverage at regular spatial resolution, but do not directly measure surface NO2. This study compares regression methods using satellite NO2 data from the TROPospheric Ozone Monitoring Instrument (TROPOMI) to estimate annual surface NO2 concentrations in varying geographic and land use settings across the continental U.S. We then apply the best‐performing regression models to estimate surface NO2 at 0.01° by 0.01° resolution, and we term this estimate as quasi‐NO2 (qNO2). qNO2 agrees best with measurements at suburban sites (cross‐validation (CV) R2 = 0.72) and away from major roads (CV R2 = 0.75). Among U.S. regions, qNO2 agrees best with measurements in the Midwest (CV R2 = 0.89) and agrees least in the Southwest (CV R2 = 0.65). To account for the non‐Gaussian distribution of TROPOMI NO2, we apply data transforms, with the Anscombe transform yielding highest agreement across the continental U.S. (CV R2 = 0.77). The interpretability, minimal computational cost, and health relevance of qNO2 facilitates use of satellite data in a wide range of air quality applications.

Reducing Greenhouse Gas Emissions and Modifying Nitrous Oxide Delivery at Stanford: Observational, Pilot Intervention Study.

Inhalational anesthetic agents are a major source of potent greenhouse gases in the medical sector, and reducing their emissions is a readily addressable goal. Nitrous oxide (N2O) has a long environmental half-life relative to carbon dioxide combined with a low clinical potency, leading to relatively large amounts of N2O being stored in cryogenic tanks and H cylinders for use, increasing the chance of pollution through leaks. Building on previous findings, Stanford Health Care's (SHC's) N2O emissions were analyzed at 2 campuses and targeted for waste reduction as a precursor to system-wide reductions. We aimed to determine the extent of N2O pollution at SHC and subsequently whether using E-cylinders for N2O storage and delivery at the point of care in SHC's ambulatory surgery centers could reduce system-wide emissions. In phase 1, total SHC (Palo Alto, California) N2O purchase data for calendar year 2022 were collected and compared (volume and cost) to total Palo Alto clinical delivery data using Epic electronic health records. In phase 2, a pilot study was conducted in the 8 operating rooms of SHC campus A (Redwood City). The central N2O pipelines were disconnected, and E-cylinders were used in each operating room. E-cylinders were weighed before and after use on a weekly basis for comparison to Epic N2O delivery data over a 5-week period. In phase 3, after successful implementation, the same methodology was applied to campus B, one of 3 facilities in Palo Alto. In phase 1, total N2O purchased in 2022 was 8,217,449 L (33,201.8 lbs) at a total cost of US $63,298. Of this, only 780,882.2 L (9.5%) of N2O was delivered to patients, with 7,436,566.8 L (90.5%) or US $57,285 worth lost or wasted. In phase 2, the total mass of N2O use from E-cylinders was 7.4 lbs (1 lb N2O=247.5 L) or 1831.5 L at campus A. Epic data showed that the total N2O volume delivered was 1839.3 L (7.4 lbs). In phase 3, the total mass of N2O use from E-cylinders was 10.4 lbs or 2574 L at campus B (confirming reliability within error propagation margins). Epic data showed that the total N2O volume delivered was 2840.3 L (11.5 lbs). Over phases 2 and 3, total use for campuses A and B was less than the volume of 3 E-cylinders (1 E-cylinder=1590 L). Converting N2O delivery from centralized storage to point-of-care E-cylinders dramatically reduced waste and expense with no detriment to patient care. Our results provide strong evidence for analyzing N2O storage in health care systems that rely on centralized storage, and consideration of E-cylinder implementation to reduce emissions. The reduction in N2O waste will help meet SHC's goal of reducing scope 1 and 2 emissions by 50% before 2030.

Effect of methane addition on supercritical water oxidation of poultry manure in the flow mode

The paper presents the research results of the supercritical water oxidation (SCWO) of poultry manure continuously fed into a tubular reactor both in the absence and presence of methane as an auxiliary fuel. The tests were conducted at a temperature gradient along the vertical axis of the reactor (top to bottom: 390–600 °C), a pressure of 25 MPa, and varying reagent flow rates. It is shown that due to heat generation during methane oxidation the energy consumption from external sources is reduced by 1.3–1.5 times depending on the ratio of reagent flow rates. The gas products contain CO2, N2, and trace amounts of N2O. The ash residues are predominantly composed of calcite and hydroxyapatite. The addition of methane results in a reduction in the content of phenols and polycyclic aromatic hydrocarbons present in the aqueous effluent, while content of N-bearing aromatics increases. The formation of nitrophenols was observed at elevated oxygen concentrations in the reaction mixture. It was revealed that excess oxygen plays a pivotal role in the efficacy of organic nitrogen removal. The formation of mineral acids and a high level of ammonia in the reaction mixture during the SCWO of poultry manure result in corrosion of stainless steel and copper seals, which in turn leads to an increased concentration of chromium and copper in the aqueous effluent. The results obtained indicate the potential for utilizing natural gas in an environmentally friendly and resource-saving manner for poultry manure processing by SCWO in autothermal mode.

Magnetite addition reduces nitrite requirement for efficient anaerobic ammonium oxidation by facilitating mutualism of ANAMMOX and FEAMMOX bacteria

Partial nitrification (PN) is crucial for anaerobic ammonium oxidation (ANAMMOX), but faces challenges such as high energy demands and process control. Recent research has highlighted additives like magnetite as potential alternatives to conventional electron acceptors (O₂ and NO₂−) for enhancing ammonium (NH4+) oxidation with lower energy consumption. This study investigated the effect of adding 50 mg/L of magnetite to ANAMMOX reactors, resulting in improved nitrogen (N) removal efficiency. The magnetite-added ANAMMOX (M-ANA) reactor yielded N removal efficiencies of 71 %, 66 %, and 57 % for NH4+:NO2− molar ratios of 1:1.3, 1:0.8, and 1:0.5, respectively. The M-ANA reactor operated under a 0.5 mol lower NO2− concentration achieved similar performance to the control ANAMMOX (C-ANA) reactor operated with a theoretical amount of NO2−. Moreover, the M-ANA reactor showed the potential to remove NH4+ by 56 % without any NO2− supplementation. Metagenomic analysis showed that the addition of magnetite significantly improved the relative abundance of microorganisms involved in the FEAMMOX reaction, such as Fimbriimonas ginsengisoli and Pseudomonas stutzeri. It also facilitated positive mutualism between ANAMMOX and FEAMMOX reactions. In addition, M-ANA granules exhibited a dense and compact structure compared with C-ANA, and the presence of magnetite facilitated the formation of resilient granules. Notably, the useful protein (Heme C) concentration and specific microbial activity in the M-ANA reactor were 1.3 and 2.2 times higher than those in the C-ANA reactor. Overall, the results demonstrate that an appropriate amount of magnetite can enhance the N removal efficiency while reducing the energy input requirements and associated carbon emissions. These findings can guide the future development of carbon- and energy-neutral N removal processes.

Controllable synthesis of cross-linked 3D ZnO nanosheet toward a nitrite electrochemical sensor

A 3D cross-linked ZnO (cl-ZnO) nanosheets were prepared via a simple one-pot hydrothermal approach, and then characterized by a series of modern advanced technique including XRD, SEM, TEM and XPS. This nanomaterial was used to modify the glass carbon electrode (GCE), obtaining an electrochemical sensor (cl-ZnO/GCE) of which the electrochemical properties were studied using various electrochemical techniques such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The sensor exhibited remarkably enhanced electrocatalytic activity for nitrite ions (NO2-) in comparison to that of the commercially available ZnO-modified GCE. Two electrochemical techniques, including chronoamperometry (CA) and linear sweep voltammetry (LSV) were adopted to test the determination performance of the sensor for nitrite, it exhibited a good linear relationship within the range of 0.8 μmol·L-1 - 0.462 mmol·L-1 and 0.608 - 7.84 mmol·L-1 evaluated by CA, the limit of detection (LOD) and sensitivity for NO2- were 0.26 μmol·L-1 (S/N = 3) and 824.6 µA (mmol·L-1)-1cm-2, respectively. For LSV, the two linearity responses of 0.95 μmol·L-1- 0.515 mmol·L-1 and 0.667 mmol·L-1- 5.41 mmol·L-1, high sensitivity of 1336.1 µA (mmol·L-1)-1cm-2 with low LOD of 0.32 μmol·L-1 were gained. This sensor can be employed to detect trace amount of NO2- in ham sausage and pickled vegetables successfully, supporting an insight and strategy for more sensitive nitrite electrochemical sensor.

Towards Integration of Ni-Slag Cleaning Process and Lithium-Ion Battery Recycling for an Efficient Recovery of Valuable Metals

Spent lithium-ion batteries (SBs) are important sources of valuable and critical raw materials. An integration of battery recycling with well-established primary processes for metals production has many advantages. In this work, the recycling of two battery scrap fractions obtained from mechanical pretreatment was integrated with a Ni-slag cleaning process at laboratory scale. Graphite from SBs acted as the main reductant, and the reduction behavior of major and trace elements was investigated as a function of time at 1350 °C. Major CO and CO2 concentrations, as well as minor amounts of SO2, NO2, CH4, and C2H4, were detected in the off-gas line. The evolution of gases took place within the first minutes of the experiments, which indicated that metal oxide reduction reactions as well as decomposition of the organic binders both happened very rapidly. This result is in line with the analytical results obtained for the slag phase, where the most significant metal oxide reduction was observed to take place within the first 5 to 10 minutes of the experiments. The distribution coefficient values for Co and Ni between metal alloy and slag as well as between matte and slag showed no significant differences when battery scrap fractions with different compositions were used. The addition of Ni-concentrate in the starting mixture resulted in increasing recoveries of Ni and Co, as well as improved settling of the matte phase.

Enhancing ammonia combustion performance using hydrogen peroxide-enriched air: A computational fluid dynamics analysis

The effect of H2O2 addition to the air on ammonia combustion was investigated in the current research using a computational fluid dynamics approach. The numerical simulation was conducted in a 10-kW laboratory-scale furnace. The oxidizer and fuel were injected into the furnace in a non-premixed mode. Furthermore, a kinetic study was carried out to analyze the sensitivity of NO production during combustion and to determine reaction pathways under various conditions. The findings indicate that the addition of H2O2 to the mixture increases flame temperature and NO levels, while decreasing N2O levels. Moreover, the study demonstrates that, with a maximum concentration of only 10 ppm, the amount of NO2 is very low under various percentages of H2O2 and different operating conditions. Furthermore, it is concluded that during ammonia/air combustion, lowering the oxidizer inlet temperature and increasing wall heat extraction may cause the combustion to become unstable. Under pure air oxidizer conditions, where Tin = 973 K and Twall = 1273 K, the combustion is stable. However, instability occurs when Twall falls to 1173 K. In this instance, adding merely 5 % H2O2 to the oxidizer is sufficient to provide self-sustaining and stable burning. More H2O2 must be introduced into the furnace to maintain stable combustion as Tin and Twall continue to decline. Interestingly, while adding H2O2 raises NO levels, decreasing the inlet and wall temperatures at higher H2O2 concentrations can help regulate NO emissions. These findings clearly indicate that introducing H2O2 into the fuel mixture could be a promising strategy for reducing the inlet temperature and enhancing heat extraction, which will both reduce energy consumption and increase system efficiency.

Impact of soil moisture regimes on greenhouse gas emissions, soil microbial biomass, and enzymatic activity in long-term fertilized paddy soil

Two potent greenhouse gases that are mostly found in agricultural soils are methane and nitrous oxide. Therefore, we investigated the effect of different moisture regimes on microbial stoichiometry, enzymatic activity, and greenhouse gas emissions in long-term paddy soils. The treatments included a control (CK; no addition), chemical fertilizer (NPK), and NPK + cattle manure (NPKM) and two moisture regimes such as 60% water-filled pore spaces (WFPS) and flooding. The results revealed that 60% water-filled pore spaces (WFPS) emit higher amounts of N2O than flooded soil, while in the case of CH4 the flooded soil emits more CH4 emission compared to 60% WFPS. At 60% WFPS higher N2O flux values were recorded for control, NPK, and NPKM which are 2.3, 3.1, and 3.5 µg kg−1, respectively. In flooded soil, the CH4 flux emission was higher, and the NPKM treatment recorded the maximum CH4 emissions (3.8 µg kg−1) followed by NPK (3.2 µg kg−1) and CK (1.7 µg kg−1). The dissolved organic carbon (DOC) was increased by 15–27% under all flooded treatments as compared to 60% WPFS treatments. The microbial biomass carbon, nitrogen, and phosphorus (MBC, MBN, and MBP) significantly increased in the flooded treatments by 8–12%, 14–21%, and 4–22%, respectively when compared to 60% WFPS. The urease enzyme was influenced by moisture conditions, and significantly increased by 42–54% in flooded soil compared with 60% WFPS while having little effect on the β-glucosidase (BG) and acid phosphatase (AcP) enzymes. Moreover DOC, MBC, and pH showed a significant positive relationship with cumulative CH4, while DOC showed a significant relationship with cumulative N2O. In the random forest model, soil moisture, MBC, DOC, pH, and enzymatic activities were the most important factors for GHG emissions. The PLS-PM analysis showed that soil properties and enzymes possessed significantly directly impacted on CH4 and N2O emissions, while SMB had indirect positive effect on CH4 and N2O emissions.

Effect of Partial Substitution of Chemical Fertilizers with Organic Fertilizers on N2O and NO Emissions from a Peach Orchard

Organic fertilizer substitution has been promoted as a weight loss, efficient, and diversified fertilizer substitution technology in agricultural production. However, there is a lack of comprehensive assessment of the impact of organic fertilizers on N2O and NO emissions from orchards. In this study, N2O and NO emissions from peach orchards were observed annually using static dark box-gas chromatography to compare the effects of chemical fertilizer application alone and partial replacement of chemical fertilizer treatment on NO emissions from peach orchards. The results showed that the partial replacement of chemical fertilizers with organic fertilizers reduced the total N2O and NO emissions from peach orchards by 15.0 % and 9.4 %, respectively. The N2O and NO emission factors were reduced by 21.3 % and 21.1 %. The mineral N content of the soil in the organic fertilizer treatment was lower than that in the chemical fertilizer treatment alone. The organic fertilizer treatment increased the contribution of AOA to nitrification and decreased the contribution of AOB, thus reducing N2O and NO from nitrification. In addition, the results of the dual isotope mixing model[δ18O(N2O/H2O) vs. δ15NSP] indicated that the bacterial denitrification/nitrifying bacterial denitrification (bD/nD) process served as the primary pathway for N2O emissions in peach orchards. Partial substitution with organic fertilizers enhanced soil denitrification, resulting in larger reductions in the amounts of N2O and NO. Therefore, partial substitution of organic fertilizer is a viable measure to mitigate nitrogen oxide emissions from orchards and to achieve green and low-carbon development in agriculture.