Carbon Monoxide Enhancements Research Articles

Beyond summative Effects: Synergistic enhancement in the gaseous interfacial reduction of Wüstite by the combined use of hydrogen and carbon monoxide

Growing environmental concerns are driving the steel industry to explore cleaner energy options, with hydrogen emerging as a promising alternative to fossil fuels. Our study investigates the interactions between hydrogen and carbon monoxide during the isothermal reduction of wüstite at 800 °C, focusing on the interfacial reaction as the rate-determining step. Using linear programming, we predict the reduction rate in the hydrogen-carbon monoxide mixture gas by quantifying each component’s contribution, validated with less than 6 % error. Hydrogen exhibits a reducing power 1.6 times that of carbon monoxide. When the total concentration of hydrogen and carbon monoxide is 30 %, an enhancement in carbon monoxide’s oxygen removal capability in ‘terrain’ regions visited by hydrogen increases the carbon monoxide utilization ratio by 1.51 times, primarily through increasing the average pore diameter to 30.28 nm. Furthermore, our study introduces the ‘waterfall’ effect, a concept derived from exploring the synergistic mechanisms between hydrogen and carbon monoxide.

Aerosol responses to precipitation along North American air trajectories arriving at Bermuda.

North American pollution outflow is ubiquitous over the western North Atlantic Ocean, especially in winter, making this location a suitable natural laboratory for investigating the impact of precipitation on aerosol particles along air mass trajectories. We take advantage of observational data collected at Bermuda to seasonally assess the sensitivity of aerosol mass concentrations and volume size distributions to accumulated precipitation along trajectories (APT). The mass concentration of particulate matter with aerodynamic diameter less than 2.5 μm normalized by the enhancement of carbon monoxide above background (PM2.5/ΔCO) at Bermuda was used to estimate the degree of aerosol loss during transport to Bermuda. Results for December–February (DJF) show that most trajectories come from North America and have the highest APTs, resulting in a significant reduction (by 53 %) in PM2.5/ΔCO under high-APT conditions (> 13.5 mm) relative to low-APT conditions (< 0.9 mm). Moreover, PM2.5/ΔCO was most sensitive to increases in APT up to 5 mm (−0.044 μg m−3 ppbv−1 mm−1) and less sensitive to increases in APT over 5 mm. While anthropogenic PM2.5 constituents (e.g., black carbon, sulfate, organic carbon) decrease with high APT, sea salt, in contrast, was comparable between high- and low-APT conditions owing to enhanced local wind and sea salt emissions in high-APT conditions. The greater sensitivity of the fine-mode volume concentrations (versus coarse mode) to wet scavenging is evident from AErosol RObotic NETwork (AERONET) volume size distribution data. A combination of GEOS-Chem model simulations of the 210Pb submicron aerosol tracer and its gaseous precursor 222Rn reveals that (i) surface aerosol particles at Bermuda are most impacted by wet scavenging in winter and spring (due to large-scale precipitation) with a maximum in March, whereas convective scavenging plays a substantial role in summer; and (ii) North American 222Rn tracer emissions contribute most to surface 210Pb concentrations at Bermuda in winter (~75 %–80 %), indicating that air masses arriving at Bermuda experience large-scale precipitation scavenging while traveling from North America. A case study flight from the ACTIVATE field campaign on 22 February 2020 reveals a significant reduction in aerosol number and volume concentrations during air mass transport off the US East Coast associated with increased cloud fraction and precipitation. These results highlight the sensitivity of remote marine boundary layer aerosol characteristics to precipitation along trajectories, especially when the air mass source is continental outflow from polluted regions like the US East Coast.

Enhancement in carbon monoxide sensing performance by reduced graphene oxide/trimanganese tetraoxide system

The article reports enhanced sensing response of reduced graphene oxide (rGO)-trimanganese tetraoxide (Mn3O4) nanocomposite gas sensor towards carbon monoxide (CO) at 298 K in a humid background. The outstanding performance of this sensor is mainly due to its high gas absorbing nature owing to uniform morphology and increased conductivity of rGO-Mn3O4 network. The sensor exhibits high sensitivity, good stability, quick response and rapid recovery. Furthermore, rGO-Mn3O4 sensor is showing better response time and reduced recovery time. The sensor response time for 50 ppm of CO is 3 s at 298 K, whereas for 20 ppm, it is 8 s. Gas sensing response at room temperature is around 70 % for 50 ppm of CO. The sensor also showed enhanced sensing at 473 K for low concentration (4 ppm of CO) with response time of 2 s and recovery time 5 s, respectively. Humidity independent sensor signal along with reduced response time, especially at a low operating temperature makes this sensor a very promising material for CO detection in conditions of variable humidity.

Impact of biomass burning on a metropolitan area in the Amazon during the 2015 El Niño: The enhancement of carbon monoxide and levoglucosan concentrations

Extreme droughts associated with changes in the climate have occurred every 5 years in the Amazon during the 21st century, with the most severe being in 2015. The increase in biomass burning (BB) events that occurred during the 2015 drought had several negative socioeconomic and environmental impacts, one of which was a decrease in the air quality. This study is an investigation into the air quality in the Manaus Metropolitan Region (MMR) (central Amazon, Brazil) during the dry (September to October) and wet (April to May) seasons of 2015 and 2016. A strong El Niño event began during the wet season of 2015 and ended during the wet season of 2016. Particulate matter samples were collected in the MMR during 2015 and 2016, and analyses of the satellite-estimated total carbon monoxide (CO) column and observed levoglucosan concentrations were carried out. Levoglucosan has been shown to be significantly correlated with regional fires and is a well-established chemical tracer for the atmospheric particulates emitted by BB, and CO can be treated as a gaseous-phase tracer for BB. The number of BB events increased significantly during the El Niño period when compared to the average number during 2003–2016. Consequently, the total CO column and levoglucosan concentration values in the MMR increased by 15% and 500%, respectively, when compared to the normal conditions. These results indicate that during the period that was analyzed, the impacts of BB were exacerbated during the strong El Niño event as compared to the non-El Niño period. In this study, we provided evidence that the air quality in the MMR will degrade in the future if droughts and BB occurrences continue to increase.

A latitudinal survey of CO, OCS, H2O, and SO2 in the lower atmosphere of Venus: Spectroscopic studies using VIRTIS‐H

The high‐resolution channel (R ≃ 2000) of the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) instrument (VIRTIS‐H) aboard Venus Express has provided numerous spectra of the nightside infrared thermal emission in the 2.3‐μm window. Mixing ratios of various minor species in the 30–40 km range could therefore be inferred using this spectral window at higher latitudes accessible to the spacecraft but which cannot be observed from Earth. The previously known enhancement in carbon monoxide (CO) toward high latitudes is confirmed and extended up to 60° with a mixing ratio varying from 24 ± 3 to 31 ± 2 ppmv at 36 km. Measurements of carbonyl sulfide (OCS) also agree with the previously suspected latitudinal variations that are anticorrelated with those of CO, ranging between 2.5 ± 1 and 4 ± 1 ppmv at 33 km. New constraints were also derived on the mean abundance of water vapor (H2O, 31 ± 2 ppmv) and sulfur dioxide (SO2, 130 ± 50 ppmv) in the probed altitude range. CO and OCS variations are interpreted as caused by large‐scale vertical motions, an explanation under current testing by various chemical and dynamical modeling. In such a case, these variations may help constrain the chemical time scale of those species in the lower troposphere.

Effects of biomass burning on summertime nonmethane hydrocarbon concentrations in the Canadian wetlands

Approximately 900 whole air samples were collected and assayed for selected C2‐C10hydrocarbons and seven halocarbons during the 5‐week Arctic Boundary Layer Expedition (ABLE) 3B conducted in eastern Canadian wetland areas. In more than half of the 46 vertical profiles flown, enhanced nonmethane hydrocarbon (NMHC) concentrations attributable to plumes from Canadian forest fires were observed. Urban plumes, also enhanced in many NMHCs, were separately identified by their high correlation with elevated levels of perchloroethene. Emission factors relative to ethane were determined for 21 hydrocarbons released from Canadian biomass burning. Using these data for ethane, ethyne, propane,n‐butane, and carbon monoxide enhancements from the literature, global emissions of these four NMHCs were estimated. Because of its very short atmospheric lifetime and its below detection limit background mixing ratio, 1,3‐butadiene is an excellent indicator of recent combustion. No statistically significant emissions of nitrous oxide, isoprene, or CFC 12 were observed in the biomass‐burning plumes encountered during ABLE 3B. The presence of the short‐lived biogenically emitted isoprene at altitudes as high as 3000 m implies that mixing within the planetary boundary layer (PBL) was rapid. Although background levels of the longer‐lived NMHCs in this Canadian region increase during the fire season, isoprene still dominated local hydroxyl radical photochemistry within the PBL except in the immediate vicinity of active fires. The average biomass‐burning emission ratios for hydrocarbons from an active fire sampled within minutes of combustion were, relative to ethane, ethene, 2.45; ethyne 0.57; propane, 0.25; propene, 0.73; propyne, 0.06;n‐butane, 0.09;i;‐butane, 0.01; 1‐butene, 0.14;cis‐2‐butene, 0.02;trans‐2‐butene, 0.03;i‐butylene, 0.07; 1,3‐butadiene, 0.12;n‐pentane, 0.05;i‐pentane, 0.03; 1‐pentene, 0.06;n‐hexane, 0.05; 1‐hexene, 0.07; benzene, 0.37; toluene, 0.16.