Gas Humidity Research Articles

Performance and durability of Ni–Co alloy cermet anodes for solid oxide fuel cells

Ni alloys are examined as redox-resistant alternatives to pure Ni for solid oxide fuel cell (SOFC) anodes. Among the various candidate alloys, Ni–Co alloys are selected due to their thermochemical stability in the SOFC anode environment. Ni–Co alloy cermet anodes are prepared by ammonia co-precipitation, and their electrochemical performance and microstructure are evaluated. Ni–Co alloy anodes exhibit high durability against redox cycling, whilst the current-voltage characteristics are comparable to those of pure Ni cermet anodes. Microstructural observation reveals that cobalt-rich oxide layers on the outer surface of the Ni–Co alloy particles protect against further oxidation within the Ni alloy. In long-term durability tests using highly humidified hydrogen gas, the use of a Ni–Co cermet with Gd-doped CeO2 suppresses degradation of the power generation performance. It is concluded that Ni–Co alloy cermet anodes are highly attractive for the development of robust SOFCs.

Water movement through an anion exchange membrane fuel cell (AEMFC): Influence of gas humidity and flow rate

The water movement between the anodic and cathodic sides of a fuel cell (AEMFCs) motivated the analysis of the effect exerted by the operational conditions on the water direction using a commercial anion exchange membrane (IONOMR®). This work shows the capability to favor the electro-osmotic drag (EOD) or the diffusion water transport mechanisms under different gas flow rates and humidities. Accordingly, the results demonstrated that the EOD predominance was promoted when low symmetric flow rates (125 cm3 min−1 for anode and cathode) were used in the AEMFC, suggesting membrane dehydration. On the contrary, the water diffusion dominance appears under asymmetric flow rates between anode and cathode (125 and 250 cm3 min−1, respectively); under these conditions, the membrane dehydration might be suppressed by anode flooding alleviation. The AEMFC performance was affected by the water transport mechanism, giving lower peak power densities for EOD-dominated systems (35.2 mW cm−2 at 60 °C) than those obtained by diffusion (62.8 mW cm−2 at 60 °C). The most suitable operating condition is under water-diffusion at non-saturated streams (below 65%), where a decrease in performance is experienced as the humidifier temperature increases from 60 °C to 80 °C (supersaturated flow), giving peak power densities of 62.8 and 3.7 mW cm−2, respectively.

Effects of structure and chemistry on electrochemical transport properties of anion exchange membranes for separation of CO2

ABSTRACT The effects of structure, chemistry, and morphology of an anion exchange membrane (AEM) for separation of CO2 from a humidified gas mixture were characterized to determine the influence on the kinetics and transport properties of a membrane electrode assembly (MEA). Supported and unsupported membranes with thicknesses of 30 µm and 50 µm were used to determine through-plane resistance, ion transport capacity, and gas diffusion properties. The effects of membrane saturation on the membrane resistance was characterized by impedance measurements under conditions with varying relative humidity from 0% to 100%. Permeability measurements with varying CO2 concentration from 1% CO2 to 10% CO2 at temperatures of 25°C and 35°C determined changes in the membrane behavior, which could influence the performance of the CO2 separating MEA. This study characterized how AEM properties influence the behavior and performance of an electrochemical separating CO2 MEA suitable for high-humidity, low CO2 concentration environments. Pt and IrO2 electrodes were used evaluate the performance of unsupported and supported membranes within a MEA, characterized by electrochemical impedance spectroscopy (EIS), linear sweep voltammetry (LSV), and constant-current measurements to examine the CO2 electromigration.

A versatile gas transmission device with precise humidity control for QCM humidity sensor characterizations

Previously, several high-sensitivity and inexpensive humidity sensors with rapid response times have been reported. However, obtaining reliable humidity characteristics of highly sensitive devices, such as quartz crystal microbalance (QCM) sensors, requires the development of new, affordable gas transmission setups. With that in mind, we developed a novel, comprehensive gas transmission system that combined elements from two commonly used systems (saturated salts and gas mixing), which facilitated automatic gas humidity changes, reliable gas flows in closed measurement chambers, and limited the influence of the external atmosphere/pollutants. The gas transmission device performance was tested using a commercial digital hygrometer and highly sensitive QCM coated with graphene oxide for six different humidity sets in range 5.3–82.6% RH. The dynamic repeatability tests proved the superb stability of the system, as QCM frequency deviation did not exceed 2% of frequency shifts among ten switching cycles (one hour each). Therefore, this system allowed a thorough investigation of humidity sensors properties in a controlled environment with a high precision.

Enhanced MEA Performance for an Intermediate-Temperature Fuel Cell with a KH5(PO4)2-Doped Polybenzimidazole Membrane.

This work exhibits an effective approach to enhance the performance of membrane-electrode assembly (MEA) with KH5(PO4)2-doped PBI membrane, by adding phosphoric acid (PA) in the catalyst layer (CL). The ohmic resistance and single-cell performance of the MEA, treated with PA, are reduced by ~80% and improved by ~800%, respectively, compared to that of untreated MEA. Based on the MEA pretreated with PA, the influence of humidity and temperature on the resistance and the single-cell performance are investigated. Under humidified gas conditions, the ohmic resistance of MEA is reduced but the charge transfer resistance is slightly increased. Regarding the effect of temperature, the ohmic resistance of MEA becomes lower as the temperature elevates from 140 to 180 °C, but increases at 200 °C. The maximum peak power density presents at 180 °C and 20% RH with 454 mW cm−2. The peak power density is favored with temperature increase from 140 to 180 °C, but decreases with further increase to 200 °C. Moreover, when dry gas conditions are employed, the output performance is unstable, suggesting that humidification is necessary to inhibit degradation for a long-term stability test.

An IoT Based Worker Safety Helmet Using Cloud Computing Technology

Miner safety and security is a major challenge around the world due to the exposure to toxic gases that are frequently released in underground mines. Miners' health is adversely affected primarily by toxic gases, which endanger the workers' lives. Furthermore, human sensory abilities do not detect these dangerous gases. As a result, this paper proposes a safety monitoring system that includes a temperature sensor, humidity sensor, and gas sensors to detect harmful gases and alert miners to those harmful gases using the smart helmet they wear. These gases are transmitted to the control station via the cloud using Internet of Things devices. The station monitors parameters like temperature, humidity, and toxic gases like methane and carbon monoxide to detect any abnormalities and alert the miner via a buzzer on the helmet. The data is processed by the Thing Speak cloud, which enables users to communicate via internet-connected devices and displays a field graph of the transmitted data.

Fabrication of Low Loading Ag Electrodes for CO2 Reduction Reaction in Zero-Gap Electrolyzer

In recent years, there has been intense effort directed towards catalyst development and electrode design for electrochemical carbon dioxide reduction reaction (CO2RR) with an objective of achieving high production rate (current density) of desirable products including CO, CH3OH, CH4 and C2+ hydrocarbons. Silver electrocatalyst is reported to exhibit remarkable CO selectivity and high current density, both of which are requisite parameters for CO2RR electrolyzer scale up. Silver is still moderately priced and reduction of Ag loading in CO2RR electrode is one of the technological goals for electrolyzer development.Most of the prior studies on Ag electrodes for CO2RR have utilized Ag nanoparticles, which are typically spray coated on a substrate from Ag or Ag-ionomer suspension resulting in high-Ag loading (> 1 mg/cm2 loading) and hence low mass specific activity (MSA) < 150 mA.mg-1 Ag. In this work, we developed a combined approach for Ag deposition using pulse electrodeposition (PE) and spray coating (SC) with an aim of decreasing Ag loading and increasing MSA. Such electrodes were found to exhibit high current densities and CO selectivity even with low Ag loading (< 0.5 mg/cm2).Specifically, several different gas diffusion electrodes (GDE) prepared by pulse electrodeposition of silver, spray coating of Ag nanoparticles, and combination of the two were prepared by coating of Sigracet gas diffusion layer (GDL). Commercial IrO2 electrode and the fabricated silver electrode were utilized as the anode and cathode, respectively. The anode and the cathode were separated by a polymer electrolyte membrane, which was Sustainion® X37-50 Grade 60- an anion exchange membrane. 10 mM KHCO3 electrolyte was re-circulated at the anode using a pump while humidified CO2 gas was flowed through the cathode. CO2RR tests are performed in a zero-gap electrolyzer setup, at a temperature of 25 °C.The main findings are summarized in the Figure below. The electrode prepared by pulse electrodeposition (PE) exhibits a low areal current density (~30 mA/cm2) but high mass-specific activity of 302 mA.mg-1 Ag. However, the selectivity for CO is low. On the other hand, spray coated (SC) electrodes yield higher CO selectivity and higher areal current density but mass specific activity is lower. By depositing silver sequentially, either pulse electrodeposition (PE) followed by spray coating (SC), i.e. the SC+PE electrode, or SC followed by PE (PE+SC electrode), both the mass-specific and areal current density increased drastically while CO selectivity remained high (99%). In particular, the current densities of the PE and SC electrodes are improved by 2 and 4.5 times, respectively, from 31 and 70 mA.cm-2 up to 136 mA.cm-2 on the SP+PE electrode, at the cell voltage of -3 V. Also, the CO selectivity of the electrodes is improved from 25 % (PE sample) and 81 % (SC sample) up to 99 % on the SC+PE electrode. The optimized electrode provided a catalyst layer with high surface coverage of silver on the GDL substrate at low Ag loadings (<0.5 mg/cm2). Further optimization of electrode is underway including modification of silver deposition and incorporation of ionomer to increase current density while maintaining the CO selectivity and durability of GDE. Details of the electrode fabrication and characterization as well as performance evaluation will be presented at the meeting. Figure 1

Determining the Influence of Catalyst Layer Architecture and Reactant Flow in an MEA for the Electrochemical Nitrogen Reduction Reaction Under Ambient Conditions

Ammonia (NH3) has been increasingly recognized as an advantageous energy/hydrogen carrier beyond agriculture use to assist in the achievement of net-zero and decarbonization goals. For over a century, NH3 production has been dominated by the thermochemical Haber-Bosch process which consumes significant fossil fuel-related energy and feedstocks with a heavy carbon footprint. By contrast, the electrochemical nitrogen reduction reaction (ENRR) presents a sustainable and modular approach to fit remote and small-scale NH3 needs, which has attracted growing interest in recent years. Rational design of electrocatalysts (e.g., introducing defects, size reduction, and heteroatom doping) has been the mainstream approach to address the bottlenecks in the ENRR, especially the low specific activity and poor faradaic efficiency. However, attempts to vary the ENRR electrolytic cell layout/design or the operating conditions have been scarce, and therefore present an opportunity to improve the NH3 electrosynthesis performance by well-thought-out reactor designs coupled with operating conditions.Our study aims to understand the influence of catalyst layer/electrode architectures and reactant mass transfer on the ENRR performance of model catalysts in a membrane electrode assembly (MEA) cell under different flow configurations. On the anode side, a platinum-coated membrane is used to oxidize the humidified H2, which provides sufficient protons for the cathode reactions. On the cathode side, electrocatalysts with commercial availability and reported ENRR activities are applied as the catalyst (e.g., noble metal, transition metal nitrides or dichalcogenides). The catalyst layer is deposited on the gas-diffusion layer and/or the proton-exchange membrane to construct a gas-diffusion electrode (GDE) and/or a catalyst-coated membrane (CCM). Subsequently, the NH3 electrosynthesis performances are evaluated under different cathode flow conditions for the varied catalyst layer architectures. Initially, the N2-saturated aqueous electrolyte (Na2SO4) is recirculated on the cathode side to flood the cathode surface constantly, which resembles the operating condition in the liquid-filled H-cell present in previous ENRR studies. In these cases, the catalytic sites are predominantly covered by proton donors (e.g., hydronium ions or water molecules) without accessing N2 molecules that only dissolve marginally (0.06 mmol/L) in aqueous media. Hence, in contrast with the “liquid-only” flow configuration, humidified N2 gas is supplied alone (“gas-only”) or in combination with the recirculated electrolyte solution (“gas-liquid”) to increase the presence of N2 near catalytic sites. When gaseous N2 is present, the gas outlet pressure (cell back pressure), as well as membrane drying, were observed to affect the current density and operational stability. Additionally, false positives are diligently recognized which arise from residual N-containing species in the MEA and environmental NH3 contamination. Linear scan voltammetry, the routine electrochemical characterization to distinguish potentially ENRR-active electrocatalysts, was found to be particularly susceptible and contribute significantly to erroneous ENRR performance. In short, This work demonstrates the challenge of getting authentic ammonia production in aqueous systems with improved electrolytic cell designs and operating conditions.

Transects of urban CO2 measurements on a bicycle‐based atmospheric sensor

It is well known that CO2 is one of the main greenhouse gases. The traffic of non-electric vehicles is the main contributor to the emissions of this gas in the cities, enhancing the urban heat island effect and increasing the dangers of global warming. The changes in the amount of CO2 across the city occur on a small urban scale, easily measured by a person moving around the city, whether it be walking or cycling. A handheld CO2 sensor capable of recording this gas, temperature, atmospheric pressure, and relative humidity was mounted on a bicycle to analyse local variations of this gas across a couple of cycling route transects in Barcelona city and a municipality within its metropolitan area. The results presented here show local CO2 variability, with some changes in concentration of up to 90ppm over distances of a few hundred metres (less than 1km). The influence of parks, urban forests, and gardens in absorbing the gas has also been identified. The measurements obtained with this technique demonstrate that using a bicycle as a scientific vehicle is a viable way to analyse the CO2 distribution in urban and suburban areas.

Concurrent Synthesis of Functional SnO2/SnO Composite for Proton Conductive Sensor and Photo-Catalytic Treatment

The hybrid materials have great significance in gas detection, photocatalysis and humidity sensing. In this paper, the SnO2/SnO material was successfully obtained by annealing Sn6O4(OH)4 at 350°C. The Sn6O4(OH)4 sample was synthesized by the co-precipitation method. The XRD analysis confirmed the formation of SnO2 and SnO phases and XPS analysis validated the results of XRD analysis (presence of the Sn2+ and Sn4+ states). The N2 adsorption-desorption isotherm revealed the mesoporous characteristic of the material along with 41.386 m2 g−1 BET surface area and 3.794 nm average pore diameter. As a sensing application, a sensor based on SnO2/SnO material was fabricated on the interdigitated electrodes and investigated under combined atmospheres of humidity levels (11%RH—33%–95%RH—11%RH) and ammonia (200–1200 ppm). The response and recovery times for the maximum response (under 11%RH–95%RH—11%RH and 1200ppm NH3) were 7 s and 26 s, respectively. The experimental observations confirmed that the resistance of the sensor depends on the concentration of H2O and NH3, both form the conjugate acid-base pair and which is responsible for the response of the sensor. Moreover, SnO2/SnO material as a catalyst possessed the good results for the degradation of MB (96%) and MO (84%) under visible light source.

Semi-dry carbonation of recycled concrete paste

Demolished concrete is a large carbon sink which has not been utilized yet. Carbonation of hydrated cement paste from old concrete can effectively store CO2, and in addition, the resulting carbonated cement paste can be used as a pozzolanic material in new composite cements. This concept reduces the CO2 footprint of cement and promotes circularity and recycling. This work investigates a semi-dry gas-solid process for the carbonation of recycled cement paste. Decreasing gas humidity and hence the content of water adsorbed on the solid cement grains limits the transport of reactants from the dissolving hydrates and the overall reaction kinetics. It also leads to co-precipitation of the carbonation products, i.e., calcium carbonate and the alumina-silica gel, into a single dense matrix within the original grains. A decreasing water availability increases also the complexity and heterogeneity of the microstructure formed, since calcium carbonate precipitates as different polymorphs, including an amorphous form, and because the final phase assemblage comprises intermediate phases such as decalcified C-(A)-S-H, remains of the original hydrates in addition to the final carbonation products.

Oxidative removal of hexane from the gas stream by dielectric barrier discharge reactor and effect of gas environment

The removal of hexane from a gas stream using a dielectric barrier discharge (DBD) reactor was conducted at ambient temperature and atmospheric pressure. The role of N2, dry and humidified air carrier gases were investigated in terms of removal efficiency and product selectivity. The oxygen concentration was also varied over the range of 0 – 21% at constant power and residence time in an N2O2 mixture for further insight into oxygen's role. A semi-empirical model of NTP-decomposition in the presence of O2, N2 and H2O is proposed. It was observed that hexane removal efficiency and product selectivity increased with increasing plasma power, regardless of the carrier gas used. The maximum removal efficiency (hexane) was 94.4% in the humidified air carrier gas. The introduction of water vapour with a relative humidity of 25% at 20 °C in the plasma DBD system significantly increased the hexane removal efficiency and CO2 selectivity (84.7%) while eliminating the production of solid residue and O3. This was probably due to the action of OH radicals. Increasing O2 concentration from 0 to 21% increased the removal efficiency and CO2 selectivity due to the generation of oxygen radicals. The results imply that the decomposition of hexane by non-thermal plasma DBDs is dominated by the effect of OH and O radicals. A semi-empirical model shows that the non-thermal plasma decomposition of hexane is first order. The DBD reactor has been demonstrated to be an effective and promising technology for removing hexane emissions from air streams. The effects of N2, O2 and H2O have been quantified, and mechanisms for their action proposed.

Unprecedented Wavelength Dependence of an Antimony Chalcohalide Photovoltaic Device

AbstractThe output of a photovoltaic (PV) device follows the Shockley diode equation, where its open‐circuit voltage (VOC) is marginally modulated by the photocurrent density and light intensity. Herein, an unprecedented wavelength‐dependent photovoltaic effect (WDPE) in antimony chalcoiodide (SbSI) and SbSI:Sb2S3 devices is reported, which demonstrate a rapid, reversible change of VOC by changing irradiation wavelength. The VOC in a SbSI:Sb2S3 device is varied from 0.35 to 0.47 V under 375 and 515 nm light without a change of photocurrent. Such a dramatic shift in VOC is not observed in silicon, perovskites, or organic solar cells. WDPE allows for a wavelength‐recognizable single‐junction photodetector without using a color filter, and is not explained by the conventional diode model. Based on the time‐resolved evaluations of charge carriers, the interfacial metastable trap of a hot carrier generated by short‐wavelength light as the origin of the observed anomalous behavior is identified. Interestingly, the trap states and photocurrent kinetics are affected by humidity and ammonium gas, which provide another multifunctional aspect of the WDPE. These findings provide deep insight into PV physics and a new way to detect color using a single cell.

Progress and prospects of research on hydrogen sensors

<p indent="0mm">The development of hydrogen energy industry is of great significance to the construction of a clean, low-carbon, safe and efficient modern energy system, the realization of the “dual carbon” goal and the high-quality economic development. The safe use of hydrogen has always been a concern. Hydrogen sensors can quickly and accurately measure hydrogen concentration, and effectively prevent hydrogen leakage, explosion and other safety problems in the process of production, storage, transportation and use. In recent years, with the popularization and application of hydrogen energy and the rapid development of Internet of Things technology, the requirements for hydrogen sensors in security, remote monitoring and distributed measurement are increasing. In this paper, the principle, applicability and research status of different types of hydrogen sensors are reviewed and analyzed, and the development trend of hydrogen sensors is forecasted. Hydrogen sensors can be divided into catalytic, electrical, optical fiber, acoustic and other types according to sensing principles. The catalytic hydrogen sensor has simple structures, fast response and high sensitivity. However, the catalytic hydrogen sensor is greatly affected by the temperature and humidity, and it has poor gas selectivity and high working temperature, which leads to potential safety hazards. The electrical hydrogen sensor has simple structures, long service life, and is easy to be integrated and miniaturized. However, electrical signals are prone to environmental interference and lead to signal drift, and electrical sparks may be generated during the detection of electrical signals, which can cause explosions in the detection of combustible gas. Compared with traditional electrical sensors, fiber optic hydrogen sensors have higher security and anti-interference, and are convenient to realize distributed measurement and other excellent performance, which has become a research hotspot. The fiber optic hydrogen sensor is small in size, intrinsically safe, anti-electromagnetic interference, and it can realize distributed spatial multi-point measurement. However, it is difficult to achieve commercial production due to its high cost, complex signal processing and expensive instruments for detection. The acoustic hydrogen sensor has high sensitivity and fast response time, but is greatly affected by temperature and humidity. The future challenges and opportunities for hydrogen sensors are also discussed in the last section. Under the background of Internet of Things and the era of big data, the research of hydrogen sensors will be gradually toward miniaturization, integration and distributed sensing. Moreover, it is necessary to realize hydrogen detection at high temperature and humidity. Future research in this field may focus on the following four aspects: (1) Reducing the cross sensitivity of temperature, humidity and other gases; (2) new hydrogen-sensitive materials such as nanomaterials and graphene; (3) performance optimization of hydrogen sensors at high temperature; (4) signal detection and demodulation device of fiber optic sensors.

Monitoring of Heated Wire Humidifier Hygrometric Performances With Heater Plate Temperature.

Under-humidification and associated complications may occur with heated humidifiers. Hygrometric performances of heated wire humidifiers are reduced by high ambient and high outlet ventilator temperatures. Currently, there is no reliable monitoring tool to evaluate humidification performances of heated wire humidifiers in the daily practice. We sought to demonstrate the relation between humidity delivered by heated wire humidifiers and different parameters that could be used to monitor humidity of gas delivered to subjects. On a bench test, we measured heater plate temperature, inlet chamber temperature, and delivered humidity with MR850 system. Temperature displayed on the humidifier was also recorded. The measurements were performed at different ambient temperatures and five minute ventilation levels (5, 7.5, 10, 12.5, 15 L/min). Inlet chamber temperatures varied from 20-40°C. In each condition, hygrometric measurements with the psychrometric method were performed at steady state. We performed 279 measurements at steady state including all conditions. We found a good correlation between heater plate temperature and absolute humidity delivered (R2 = 0.82). This relationship was hardly affected by ambient temperature, but minute ventilation had more effect. For different minute ventilations, the correlation between heater plate temperature and absolute humidity delivered was very good with coefficient of determination R2 from 0.87-0.98. Heater plate temperature > 62°C was a good predictor of absolute humidity delivered > 30 mg H2O/L (area under the curve = 0.96, sensibility 79%, specificity 94%). No correlation existed between humidity delivered and the outlet chamber temperature (displayed on the humidifier). In this bench study, we have shown a good correlation between heater plate temperature and humidity delivered with a heated wire humidifier. This means that a "hidden" hygrometer is built into the heated wire humidifier. Heater plate temperature should be used as a surrogate of humidity to improve the humidification monitoring.

Modeling the flow rate of dry part in the wet gas mixture using decision tree/kernel/non-parametric regression-based soft-computing techniques

Owing to its importance in extraction of natural gas from underground gas storage as well as its crucial role in determination of final gas mixture in the production facilities of gas/oil industry, the dry content of wet gas mixture needs to be calculated precisely. The present study explores the potential of different soft-computing techniques in estimation of the dry gas flow rate (kg/h) (output variable) of wet gas mixture based on two input variables of wet gas flow rate (kg/h) and absolute gas humidity (g/m3). Decision tree-based methods (M5P tree, random forest (RF), random tree (RT), and reduced error pruning tree (REPT) models), kernel function-based approaches (Gaussian process regression (GPR) and support vector machines (SVM)), and non-parametric regression-based technique (multivariate adaptive regression splines (MARS)) were implemented for the first time to estimate the dry gas flow rate, and their respective prediction performances were analyzed statistically. Coefficient of correlation (CC), Nash–Sutcliffe efficiency (NSE), root mean square error (RMSE), mean absolute error (MAE), Legates and McCabe's index (LMI), and Willmott's Index (WI) were used as the statistical indicators for validating the performance of each soft-computing model. While M5P model (MAE = 122.2382 kg/h, RMSE = 580.5626 kg/h, CC = 0.9875 for the testing data set) was better than other tree-based models (MAE = 363.2802–542.6119 kg/h, RMSE = 871.9363–1025.3444 kg/h, CC = 0.9587–0.9706 for the testing data set) and MARS model (MAE = 128.0083 kg/h, RMSE = 622.9515 kg/h, CC = 0.9852 for the testing data set), the statistical indicators approved the superiority of the radial basis kernel function-based GPR model (GPR-RBKF) model (MAE = 163.3266 kg/h, RMSE = 483.1359 kg/h, CC = 0.9915 for the testing data set) over other implemented models in predicting the dry gas flow rate. The findings highlighted the potential of soft-computing methodologies in precise estimation of dry gas flow rate in wet gas mixture, particularly, in situations where the measurement of such parameters with traditional deterministic models is practically not possible.

Influence of Sample Gas Humidity on Product Ion Formation in High Kinetic Energy Ion Mobility Spectrometry (HiKE-IMS).

High Kinetic Energy Ion Mobility Spectrometers (HiKE-IMS) chemically ionize gaseous samples via reactant ions and separate the generated ions by their motion in a neutral gas under the influence of an electric field. Operation at reduced pressures of 10-40 mbar allows for reaching high reduced electric field strengths (E/N) of up to 120 Td. At these high E/N, the generated ions gain the namesake high kinetic energies, leading to a decrease in cluster size of the reactant ions by increasing the reaction rate of collision-induced cluster dissociation of hydrates. In positive ion polarity and in purified air, H3O+(H2O)n, NO+(H2O)n, and O2+•(H2O)p are the most abundant reactant ions. In this work, we investigate the effect of varying sample gas humidity on product ion formation for several model substances. Results show that increasing the sample gas humidity at high E/N of 120 Td shifts product ion formation from a charge transfer dominated reaction system to a proton transfer dominated reaction system. For HiKE-IMS operated at high E/N, the reduction in cluster size of reactant ions allows ionization of analytes with low proton affinity even at high relative humidity in the sample gas of RH = 75% at 303.15 K and 1013.25 hPa. In contrast to conventional IMS, where increasing the sample gas humidity inhibits ionization for various analytes, increasing sample gas humidity in HiKE-IMS operated at 120 Td is actually beneficial for ionization yield of most analytes investigated in this work as it increases the number of H3O+(H2O)n.

Evaluating the performance of Cr-Soc-MOF Super-Adsorbents for CO2 capture from flue gas under humid condition through molecular simulation

One of the major criticisms for gas separation by utilizing Metal Organic Framework (MOF) porous material for all classes of adsorbents is their very poor performance under humidified gas streams. Very few MOFs show better CO2 separation from N2 mixture in the presence of moisture. Conversely, plenty of MOFs demonstrated good CO2 capture from dry gas streams. In order to explore the potential characteristics of gas separation under humid conditions by coordinatively unsaturated metal organic framework (CUS-MOF) with square octahedral (Soc) topology were exercised single component (CO2, N2) adsorption and co-adsorption (CO2/N2) in the presence of moisture at 298 K with pressure ranging from 0 to 10 bar. Herein, we investigated five exceptional Cr-Soc-MOFs similar to the experimentally established iso-structural topology by differing the polynuclear aromatic ring size and N-heteroatom to their pore wall. The specific interaction of guest molecules to the coordinatively unsaturated metal site (CUS), i.e., rigid μ3-oxygen-centered tri-nuclear metal carboxylate, of Cr-Soc-MOF-n series were identified with Density Functional Theory (DFT) calculations, this energy profile was used to derive specific force field. Further, Grand canonical Monte Carlo (GCMC) simulation was employed with DFT-derived force field to identify suitable CO2 capture for Cr-Soc-MOFs in the presence of moisture. Interestingly, the Cr-Soc-MOFs with larger pore volume were retained not only CO2 uptake in the range of 23 – 35 wt% but also selectivity about 20 – 50 range even up to 70% of RH. Importantly, we introduced a mathematical tool to theoretically analyze the dynamic co-adsorption in the form of breakthrough curve measurement from CO2/N2 simulated co-adsorption by mimicking the real flue gas condition, also working capacity (ΔN), Regenerability (R%) and Adsorbent Performance Indicator (API) of Cr-Soc-MOF-n series were investigated. The CO2 separation performances of Cr-Soc-MOF-n series suggested that the polynuclear aromatic ring to their pore wall withstand CO2 uptake in the presence of humidity rather than N-heteroatom decorated Cr-Soc-MOF due to its high pore volume and the accommodation of extra aromatic ring in their pore channels.

High-rate microbial electrosynthesis using a zero-gap flow cell and vapor-fed anode design

Microbial electrosynthesis (MES) cells use renewable energy to convert carbon dioxide into valuable chemical products such as methane and acetate, but chemical production rates are low and pH changes can adversely impact biocathodes. To overcome these limitations, an MES reactor was designed with a zero-gap electrode configuration with a cation exchange membrane (CEM) to achieve a low internal resistance, and a vapor-fed electrode to minimize pH changes. Liquid catholyte was pumped through a carbon felt cathode inoculated with anaerobic digester sludge, with humidified N2 gas flowing over the abiotic anode (Ti or C with a Pt catalyst) to drive water splitting. The ohmic resistance was 2.4 ± 0.5 mΩ m2, substantially lower than previous bioelectrochemical systems (20–25 mΩ m2), and the catholyte pH remained near-neutral (6.6–7.2). The MES produced a high methane production rate of 2.9 ± 1.2 L/L-d (748 mmol/m2-d, 17.4 A/m2; Ti/Pt anode) at a relatively low applied voltage of 3.1 V. In addition, acetate was produced at a rate of 940 ± 250 mmol/m2-d with 180 ± 30 mmol/m2-d for propionate. The biocathode microbial community was dominated by the methanogens of the genus Methanobrevibacter, and the acetogen of the genus Clostridium sensu stricto 1. These results demonstrate the utility of this zero-gap cell and vapor-fed anode design for increasing rates of methane and chemical production in MES.

A Smart Helmet for Secure Monitoring of Miner Data to Improve Safety

Abstract: In recent times, mining has been a dangerous activity taking a severe toll on the lives of miners. Underground mining hazards include gas poisoning, suffocation, roof collapse, and gas explosion. This project aims to develop a smart helmet based on Zigbee wireless technology to build wireless sensor networks for real-time surveillance and monitoring hazardous gases and abnormal levels of temperature and humidity in the mine. These three parameters are continuously being detected using the gas sensor(s), temperature and humidity sensor, and if the predefined limit is crossed, a buzzer and LED will be initiated. Two infrared sensors, one inside and one on the surface of the helmet, are placed to check if the helmet is properly placed and to detect collision from falling debris, respectively. These values are continuously being transmitted to the control room for monitoring. In case of any hazardous situation, the led and buzzer are activated in the control room as well as on the miner’s helmet. The helmet is powered by the energy generated from piezoelectric sensors placed in the miner’s shoes, which work on the principle of vibration detected from the miner’s movement. The safety measures included in our project can drastically help us avoid mining accidents and thus saving invaluable lives. Keywords: Smart helmet, Zigbee Technology, Gas sensor, Temperature and Humidity sensor, Infrared Sensor, Coal mines, Safety