Oxygen Absorption Research Articles

3D camera based on laser light absorption by atmospheric oxygen at 761 nm.

A 3D camera based on laser light absorption of atmospheric oxygen at 761 nm is presented. The camera uses a current-tunable single frequency distributed feedback laser for active illumination and a silicon-based image sensor as a receiver. This simple combination enables capturing 3D images with a compact and mass producible set-up. The 3D camera is validated in indoor environments. Distance accuracy of better than 4 cm is demonstrated between 4 m and 10 m distances. Future potential and improvements are discussed.

Unlocking nature's toolbox: Kinetin-producing Priestia flexa VL1 paves the way for efficient bioremediation of chromium-contaminated environments

Elevated levels of hexavalent chromium (Cr(VI)) present a severe environmental threat, leading to soil and water contamination. Traditional reduction methods, including electrochemical, photocatalytic, and microwave catalytic processes, have proven effective but face challenges such as durability, pH sensitivity, temperature constraints, varying Cr(VI) concentrations, oxygen absorption issues, and high operational costs. In contrast, soil bacteria, provide a cost-efficient and impactful solution, offering sustainable outcomes without secondary pollution concerns. Bioremediation, focusing on the microbial reduction of Cr(VI) to Cr(III), emerges as an ecologically-friendly alternative, utilizing bacterial chromium reductase as an abundant and adaptable resource for Cr(VI) remediation. We isolated Priestia flexa VL1 (PFVL1) which reduces Cr(VI) concentrations up to 200 mg/l to Cr(III). Fourier transform infrared (FTIR) spectroscopy and gas chromatography-mass spectrometry (GCMS), revealed kinetin molecules within PFVL1. Distinct expression patterns were observed in the genes responsible for Cr(VI) reduction and kinetin biosynthesis in PFVL1, contingent upon varying dosages. This investigation emphasizes PFVL1's substantial role in advancing Cr(VI) bioremediation through kinetin biosynthesis, contributing to a safer and more sustainable environment.

Study on controlling factors and developing a quantitative assessment model for spontaneous combustion hazard of coal gangue

Developing a quantitative hazard assessment model for spontaneous coal gangue combustion is imperative to ensuring the safety of coal mining operations. In this study, eight types of coal gangue from different coalfields were used to determine the controlling factors for spontaneous combustion. A variety of physical and chemical characterization methods were employed to investigate the physical and chemical characteristics of the samples. Based on the experimental results, six key parameters were identified, namely the aliphatic C–H components, pyrite sulfur content, physical oxygen absorption capacity, ash content, ignition point temperature, and activation energy for thermal decomposition. The results show that the spontaneous combustion hazard of coal gangue is positively correlated with the first three of these and is negatively correlated with the rest. Using the entropy-weight method combined with the analytic hierarchy process, appropriate weighting factors for each parameter were obtained and used to establish a quantitative assessment model for the spontaneous combustion hazard of coal gangue. This model is expected to enhance the current industrial best practices for the prevention and control of spontaneous coal gangue combustion.

Phase transformations in single-layer MoTe2 stimulated by electron irradiation and annealing

Among two-dimensional (2D) transition metal dichalcogenides (TMDs), MoTe2 is predestined for phase-engineering applications due to the small difference in free energy between the semiconducting H-phase and metallic 1T′-phase. At the same time, the complete picture of the phase evolution originating from point defects in single-layer of semiconducting H-MoTe2 via Mo6Te6 nanowires to cubic molybdenum has not yet been reported so far, and it is the topic of the present study. The occurring phase transformations in single-layer H-MoTe2 were initiated by 40–80 kV electrons in the spherical and chromatic aberration-corrected high-resolution transmission electron microscope and/or when subjected to high temperatures. We analyse the damage cross-section at voltages between 40 kV and 80 kV and relate the results to previously published values for other TMDs. Then we demonstrate that electron beam irradiation offers a route to locally transform freestanding single-layer H-MoTe2 into one-dimensional (1D) Mo6Te6 nanowires. Combining the experimental data with the results of first-principles calculations, we explain the transformations in MoTe2 single-layers and Mo6Te6 nanowires by an interplay of electron-beam-induced energy transfer, atom ejection, and oxygen absorption. Further, the effects emerging from electron irradiation are compared with those produced by in situ annealing in a vacuum until pure molybdenum crystals are obtained at temperatures of about 1000 °C. A detailed understanding of high-temperature solid-to-solid phase transformation in the 2D limit can provide insights into the applicability of this material for future device fabrication.

Isotropic optical response and edge plasmons in MoS[formula omitted] monolayer induced by oxygen absorption

Defects play a crucial role in altering the electronic and optical characteristics of two-dimensional (2D) semiconductors, which is highly significant for the advancement of next-generation electronic and optoelectronic devices. In this study, we employ first-principles density functional theory (DFT) and time-dependent DFT calculations to explore the impact of oxygen defects on the electronic, optical, and plasmonic properties of monolayer MoS2. Our calculations reveal that the presence of an oxygen defect in the absorption position of the MoS2 monolayer leads to a predominant photoabsorption in the visible region of the electromagnetic spectrum, as well as an isotropic optical response and the emergence of edge plasmons. Conversely, when an oxygen defect is located in the adsorption position of the MoS2 monolayer, it generates deep midgap states within the bandgap, resulting in an anisotropic optical response and the partial decay of edge plasmons. By obtaining a comprehensive understanding of the effects of defects on photoabsorption and plasmonics, our study provides valuable insights for enhancing the performance of optical and plasmonic devices based on 2D materials.

Oxygen absorption/desorption behaviors of Sr0.72Ca0.28Fe1-xAlxO3-δ perovskite oxygen sorbents for air separation

Perovskite-type oxides are extensively studied as oxygen sorbents in pressure swing adsorption (PSA) for air separation at elevated temperatures. However, quantitative analysis of desorption kinetics and the basis of material optimization are rarely reached on a fixed bed. In this study, the effects of Al doping on the oxygen absorption/desorption behaviors of Sr0.72Ca0.28Fe1-xAlxO3-δ (SCFA, x = 0, 0.03, 0.05, 0.07, 0.1) were investigated by temperature programmed desorption (TPD) and fixed bed absorption/desorption experiments. The desorption kinetics were analyzed by a Geometrical contraction model. O2-TPD results show that Al doping reduces the total absorption amount of Sr0.72Ca0.28FeO3-δ (SCF). Through the peak-differentiation-imitating analysis, it was found that the SCFA series materials have three different oxygen desorption sites, and the desorption peak area and temperature corresponding to each site are different. CO2-TPD results reveal that Al doping improves the CO2 resistance of the perovskite oxides. Compared with SCF, Al doped materials show enhanced equilibrium oxygen absorption capacity at temperature higher than 550 °C. The oxygen desorption rates of SCFA series were calculated by fitting the desorption curves with Geometrical contraction model (R2). Both initial oxygen desorption concentration and oxygen desorption rate constants increase with temperature but decrease with the Al doping amount. The similar apparent activation energies of the desorption rate constant of the SCFA series reveal that the desorption mechanism not changes with Al doping. Ideal oxygen production rate, equaling to the multiplication of equilibrium oxygen absorption capacity and the desorption rate constant, is suggested to evaluate the performance of an oxygen sorbent. The x = 0.03 sample shows the highest ideal oxygen production rate among the SCFA series.

Fe, Ni doped carbon nanofibers as dual functional electrocatalyst prepared by in-situ grown SiO2-protected in nanoconfinement

Fuel cells (FCs) and metal-air batteries (MABs) are promising alternatives to traditional fossil fuels, but the sluggish kinetics and irreversibility of the oxygen evolution/reduction reaction (OER/ORR) currently limit their development. Hence, developing a new bifunctional catalyst for FCs and MABs is essential, as most electrocatalysts are single functional due to their single catalytic sites. In this study, electrospinning and SiO2 coating method are combined to create a dual-atom catalysts (DACs) for ORR and OER, which included the noble-metal-free bi-sites (FeN4, NiN4) anchored carbon nanofiber (CNFs). The SiO2 nanoshells have been in-situ grown on the surface of the pre-oxidation nanofibers and prevent metal atom aggregation owing to nanoconfinement strategy, which has been a Gordian knot for synthesizing DACs. The as-obtained electrocatalyst exhibits distinguished activities for ORR (E1/2 = 0.79 V vs. RHE) and OER (Ej10 = 1.67 V vs. RHE). Furthermore, using the first-principles calculation, the charge redistribution and orbital coupling of Fe center and Ni center elucidate the enhanced catalytic activity of the material: the more positive charges benefit the absorption of oxygen while the negative shift of projected density of state (PDOS) enhance the deabsorption capacity, both of which brought about the enhanced catalytic activity.

A new efficient catalyst: Metal-organic frameworks in electrocatalysis

Global warming and ecological degradation are becoming major environmental problems in the world today. To reduce energy loss and advocate green chemistry, the development of new energy sources is very important. Electrocatalytic technology has low environmental pollution and carbon emission because only electrons are involved and there is no need to add external fuel. And metal-organic framework (MOF), with its porous structure and large surface area, can provide an ideal reaction platform for electrocatalytic reactions. This paper first introduces the discovery and development of MOF materials, followed by a discussion of the current methods for designing MOFs from several perspectives, including pore size, conductivity, and active sites. Then the development of MOF materials with transition metal ions was analysed from the perspective of the elements Fe, Co, and Ni, which exhibit higher reaction rates in comparison with ordinary MOF materials in hydrogen precipitation reaction, oxygen absorption reaction and other reactions. Finally, this paper introduced several synthetic ideas and methods of MOF and reviewed the methods to synthesise MOF electrocatalytic materials.

Planar light induced fluorescence quenching oxygen diffusivity measurement near the gas–liquid interface in aqueous glycerol and aqueous propylene glycol

Experimental diffusivity data for gases in liquid mixtures are still scarce. To measure the diffusivity of dissolved oxygen in aqueous solutions of glycerol and propylene glycol, a planar light induced fluorescence (PLIF) method has been employed. The experimental method developed allows the measurement of the concentration field near the gas–liquid interface. The results show an increased oxygen diffusivity for the aqueous glycerol solution compared to the aqueous propylene glycol solution, corresponding to the lower viscosity of the solvent. Interestingly, during the first few seconds of oxygen absorption, a reduced early diffusivity is found for both experiments compared to later times. The results are compared with selected correlations and available experimental values. In general, the results are in good agreement with the literature data found and the discrepancy between early and later diffusivity is discussed.

Relief from Toxic Effects of Oxygen Using Succinates in Patients with COVID-19 Undergoing High-Flow Oxygen Therapy

Liberal oxygen therapy for COVID-19 causes hyperoxemia in most patients and reduces their survival rate. Even moderate hyperoxemia reduces oxygen delivery, and high levels of oxygen in central venous blood increase mortality in COVID-19 patients. These facts occur due to the manifestation of toxic effects of oxygen (vasoconstriction, bronchoconstriction) requiring the use of medications that reduce toxic effects. The aim of the study was to assess the ability of succinate preparations to eliminate the toxic effects of oxygen affecting central hemodynamics and blood oxygenation in patients with COVID-19. Material and methods. The effect of medicines containing succinates (Cytoflavin and Reamberin) in stopping the manifestations of hyperoxia in 51 surviving patients with the novel coronavirus infection who received high-flow oxygen therapy (HFOT) was analyzed in a retrospective study. Results. Monitoring of heart rate, respiratory rate, SpO₂, PaO₂ and PaO₂/FiO₂ during HFOT within 12 hours from the start of oxygen therapy showed an indirect, but statistically significant effect of stopping the toxic effects of oxygen. This was expressed in a decrease in tachycardia and tachypnea [to 86.7–115.0 (at P<0.001) and 22–24 (P<0.001), respectively] against the background of concomitantly administered succinate preparations, that provided effective oxygen absorption and contributed to the effective elimination of hypoxia and hypoxemia (an increase in PaO₂/FiO₂ to 196.0 [(184.2–249.0) at P<0.001], which was confirmed by a dynamic decrease in the level of lactate (to 2.6±0.8 mmol/l at P<0.001). Conclusion. The results obtained indirectly confirm the protective effect of succinates, which are more pronounced in Citoflavin, but require additional confirmation of the hypothesis of succinate effectiveness in stopping the toxic effects of oxygen in further studies.

Mass transfer enhancement and hydrodynamic performance with wire mesh coupling solid particles in bubble column reactor

It is of vital significance to investigate mass transfer enhancements for chemical engineering processes. This work focuses on investigating the coupling influence of embedding wire mesh and adding solid particles on bubble motion and gas–liquid mass transfer process in a bubble column. Particle image velocimetry (PIV) technology was employed to analyze the flow field and bubble motion behavior, and dynamic oxygen absorption technology was used to measure the gas–liquid volumetric mass transfer coefficient kLa. The effect of embedding wire mesh, adding solid particles, and wire mesh coupling solid particles on the flow characteristic and kLa were analyzed and compared. The results show that the gas–liquid interface area increases by 33% to 72% when using the wire mesh coupling solid particles strategy compared to the gas–liquid two-phase flow, which is superior to the other two strengthening methods. Compared with the system without reinforcement, kLa in the bubble column increased by 0.5–1.8 times with wire mesh coupling solid particles method, which is higher than the sum of kLa increases with inserting wire mesh and adding particles, and the coupling reinforcement mechanism for affecting gas–liquid mass transfer process was discussed to provide a new idea for enhancing gas–liquid mass transfer.

The Rate of the Oxygen Absorption by the Styrene Epoxide–p-Toluene Sulfonic Acid Double System Depending on the Structure of the Aliphatic Tail of the Alcohol Solvent

The Rate of the Oxygen Absorption by the Styrene Epoxide–p-Toluene Sulfonic Acid Double System Depending on the Structure of the Aliphatic Tail of the Alcohol Solvent

Catechu (Senegalia catechu) based oxygen scavenger for active food packaging: A sustainable alternative

For the first time, a novel oxygen scavenging system (OSS) based on Acacia catechu (AC) and calcium carbonate (CC) was developed, and its oxygen scavenging ability was evaluated. At day 0, the oxygen content in the sample vials was 20.9%, which decreased to 12.7% and 8.3% over 20 days at 25 °C and 60 °C, respectively. The effect of concentrations of both components was analyzed by comparing final oxygen values (%) for AC1-CC1 to AC5-CC1 and control samples. The highest reduction (%) was recorded in samples AC1-CC1, which had an equal mass of both components compared to all other samples stored at the same temperature. The developed OSS demonstrated an oxygen absorption capacity of 10 ± 1.13 mL O2/g and 15.56 ± 0.51 mL O2/g at 25 °C and 60 °C respectively, whereas the reported oxygen scavenging rate for the same is 0.5 ± 0.05 mL O2/(g day) and 0.77 ± 0.02 mL O2/(g day). The observed rate constant values increased with increasing temperature from 0.02113 to 0.02350 (h−1) at 25 °C and 60 °C. Therefore, the findings of the present study demonstrated that AC–CC–based OSS with moisture activation is a suitable natural alternative to chemical-based oxygen scavengers for long-term stored foods with a moderate to high susceptibility towards oxygen.

Insight into thermal effect on the surface properties and potentials of MnO2 (α, β, ɣ) as electrocatalysts for the oxygen reduction reaction

The purpose of the work is to study the thermal behavior of MnO2 (α, β, γ) nanomaterials as well as their performance in oxygen reduction reaction (ORR) before/after thermal treatment. After thermal treatment, oxygen vacancies were introduced in all MnO2 nanomaterials that were confirmed by the high angle annular dark field (HAADF), electron energy loss spectroscopy (EELS), and X-ray photoelectron spectroscopy (XPS), etc. Furthermore, the conductivities of MnO2 (α, β, γ) nanomaterials improved after 300 °C, particularly γ-MnO2 with a five-times increase over the pristine γ-MnO2 nanomaterials. As catalysts for ORR, the specific current density and charge transfer was improved in α-MnO2 and γ-MnO2 after heat treatment, which was closely related to the increased content of Mn3+ and surface absorption oxygen (Oads). However, it was observed that the ORR activity of β-MnO2 was slightly decreased, which could be due to its lower absorption of oxygen. These results revealed that the difference in ORR activities among the three MnO2 materials can be attributed to variations in Mn3+ content, Oads content, conductivity, and the influence on morphology of thermal annealing. The overall ORR performance is influenced by a complex interplay of these factors, highlighting the importance of considering multiple aspects when studying and optimizing ORR catalysts based on MnO2 materials.

Ceramic Conversion Treatment of Commercial Pure Titanium with a Pre-Deposited Vanadium Layer

Titanium is characterized by poor wear resistance which restricts its application. Ceramic conversion treatment (CCT) is used to modify the surface; however, it is a time-consuming process. In this work, a thin vanadium layer was pre-deposited on the commercial pure titanium (CPTi) samples’ surface, and it increased the oxygen absorption significantly and assisted in obtaining a much thicker oxide layer than those samples without a V layer at the treatment temperatures of 620 °C and 660 °C. The oxidation of the samples pre-deposited with the V layer had a much higher oxidation rate, and V was evenly distributed in the oxide layer. After CCT, all samples had a low wear volume and stable coefficient of friction in comparison to the untreated CPTi sample. A slightly higher wear area in the wear track was observed on the V pre-deposited samples than those samples without vanadium, especially those with a thicker oxide layer (>4 µm). This might be associated with defects in a thicker oxide layer and insufficient support from a shallower oxygen diffusion zone or hard debris created at the initial stage. Vanadium in the oxide layer reduced the contact angles of the surface and increased the wettability significantly.

Spectres of Covid: A Survey of Post - Recovery Impacts of Covid on Oxygen Absorption

Spectres of Covid: A Survey of Post - Recovery Impacts of Covid on Oxygen Absorption

The Radical-Chain Oxidation of Tetrahydrofuran Inhibited by Tocopherol and Ascorbic Acid

The effect of ascorbic acid and α-tocopherol on the radical chain oxidation of tetrahydrofuran was studied at a temperature of 309 K. The reaction was initiated by 2,2'-azo-bis-isobutyronitrile. The process rate was monitored by the oxygen absorption. The rate constant of the tetrahydrofuran peroxyl radical reaction with α-tocopherol were measured k7 = (2.9 ± 0.6) × 105 l mol–1 s–1. The effect of an aqueous solution ascorbic acid on the oxidation rate of tetrahydrofuran was studied. The rate constant of the tetrahydrofuran peroxyl radical reaction with ascorbic acid were measured k7 = (10.2 ± 1.0) × 104 l mol–1 s–1. The effect of ascorbic acid on the tetrahydrofuran oxidation inhibited by α-tocopherol is considered. It has been shown that when both inhibitors are used together, the induction period is equal to the sum of the induction periods of individual compounds. The effective inhibition rate constant in this case is equal to k7 = (2.5 ± 0.5) × 105 l mol–1 s–1.

Time-dependent electrical and electroluminescence properties of In-substituted CaSnO3 and CaSnO3:Pr thin films prepared by a chemical solution deposition method

CaSnO3, CaSn0.9In0.1O3−δ, and Ca0.995Pr0.005Sn0.9In0.1O3−δ thin films sandwiched between (In0.975Sn0.025)2O3−δ thin-film electrodes were prepared by a chemical solution deposition method. The electric and electroluminescence properties were investigated by applying dc (direct current) voltages to the films. No appreciable current was detected for the CaSnO3 thin film. When constant dc voltage was applied to the CaSn0.9In0.1O3−δ and the Ca0.995Pr0.005Sn0.9In0.1O3−δ thin films, current was close to zero just after applying the voltage, increased with increasing time at the beginning, reached a maximum at a certain time, and then decreased with increasing time. The current increased by annealing at 673 K in air and decreased reversibly by quenching from 1323 K. Ca0.995Pr0.005Sn0.9In0.1O3−δ thin film showed reddish white electroluminescence due to f-f transitions of Pr3+ ions. The time dependence of the luminance was similar to that of the current. The results were discussed in relation to oxygen absorption and desorption at high temperatures and electromigration of oxygen vacancies at room temperature.

Study on Thermal Behavior Characteristics and Microstructure Evolution Mechanism of Residual Coal Combustion Process in Deep High Initial Temperature Environment

ABSTRACT The shallow coal seam resources are gradually reduced, the depth of coal seam mining is increased, and the underground temperature is increased, which makes the risk of residual coal fire increase year by year. In order to explore the transformation path of functional groups during oxidation and the caloric release characteristics of residual coal in deep coal mine, the microcosmic changes of coal oxidation process in deep mine were analyzed by in situ diffuse reflectance (In situ FTIR) and electron spin resonance (EPR) experiments, and macroscopic characteristics such as characteristic temperature of residual coal were tested by synchronous thermal analysis experiment. In FTIR results, it is observed that hydroxyl groups, active aliphatic hydrocarbon structures, and active oxygen-containing groups are key chemical structures involved in the oxidation process of residual coal, displaying a strong correlation transformation phenomenon. This can be described as follows: oxygen absorption led to a negative correlation between aliphatic hydrocarbon structures and hydroxyl groups, while the conversion of aliphatic hydrocarbon structures into carboxyl and aldehyde groups resulted in a negative correlation between aliphatic hydrocarbons, carboxyl groups, and aldehyde groups. Active oxygen-containing functional groups showed a positive correlation. With the increased of free radical concentration, the type of free radicals increased and the linewidth (ΔH) increased. The high-temperature environment intensified thermal behavior tendencies, increased the number of active structures, and raised the risk of spontaneous combustion. The research results provided a theoretical basis for understanding the process of coal spontaneous combustion, and had important reference value for ensuring the safe mining of deep coal seams and implementing effective disaster prevention measures.

Study on staged heat transfer law of coal spontaneous combustion in deep mines

The environmental conditions in the mining region were severely impacted by the high temperature and buried depth of residual coal, which considerably enhanced the likelihood of spontaneous coal combustion and worsened the coal's pyrolysis behavior. Therefore, the change laws of mass and heat during coal oxidation were investigated using industrial analysis and synchronous thermal analysis, and reaction models of coal samples at various phases of oxidation were derived using the Bagchi technique. The findings indicated that the activation energy during the stage of water loss and weight loss increased with the coal's water content, while the activation energy of coal in the early stage of oxidation combustion increased with lower ash percentage and higher carbon content. Additionally, the stages of water loss and weight loss and the stage of oxygen absorption and weight increase in the stable exothermic process of coal samples showed a positive correlation between DTG and DSC. The reaction models for the oxidation and combustion stages were both consistent with the number 7 reaction mechanism. The study's findings may serve as a theoretical roadmap for the further investigation and development of flame retardant avoidance strategies for residual coal oxidation in deep mines.