Gas In Presence Research Articles

Effect of toluene on siloxane biodegradation and microbial communities in biofilters

The removal of volatile methyl siloxanes (VMS) from landfill biogas is crucial for clean energy utilization. VMS are usually found together with aromatic compounds in landfill biogas of which toluene is the major representative. In the present study, two biofilters (BFs) packed with either woodchips and compost (WC) or perlite (PER) were used to study the (co–) removal of octamethyltrisiloxane (L3) and octamethylcyclotetrasiloxane (D4) from gas in presence and absence of toluene, used as a representative aromatic compound. The presence of low inlet toluene concentrations (315 ± 19 – 635 ± 80 mg toluene m-3) enhanced the VMS elimination capacity (EC) in both BFs by a factor of 1.8 to 12.6. The highest removal efficiencies for D4 (57.1 ± 1.1 %; EC = 0.12 ± 0.01 gD4 m-3 h-1) and L3 (52.0 ± 0.6 %; EC = 0.23 ± 0.01 gL3 m-3 h-1) were observed in the BF packed with WC. The first section of the BFs (EBRT = 9 min), where toluene was (almost) completely removed, accounted for the majority (87.7 ± 0.6 %) of the total VMS removal. Microbial analysis revealed the impact of VMS and toluene in the activated sludge, showing a clear selection for certain genera in samples influenced by VMS in the presence (X2) or absence (X1) of toluene, such as Pseudomonas (X1 = 0.91 and X2 = 12.0 %), Sphingobium (X1 = 0.09 and X2 = 4.04 %), Rhodococcus (X1 = 0.42 and X2 = 3.91 %), and Bacillus (X1 = 7.15 and X2 = 3.84 %). The significant maximum EC values obtained by the BFs (0.58 gVMS m-3 h-1) hold notable significance in a combined system framework as they could enhance the longevity of traditional physicochemical methods to remove VMS like activated carbon in diverse environmental scenarios.

Sustainable Commitment Scheduling for Power, Heat, and Natural Gas Dispatch

This manuscript presents commitment scheduling of power, heat and natural gas in presence of thermal generating units (TUs), cogeneration units (CUs), heat only units (HUs), solar PV plants, wind turbine generators and PEV parking lot with charging and discharging facility considering carbon capture. Power to gas technology comprising of carbon capture unit, electrolyzer, hydrogen storage unit, and methanation procedure, is used to provide natural gas demand using CO2 taken from TUs, CUs, HUs and hydrogen produced by electrolyzer. Total operative cost of TUs, CUs, HUs plus running cost of WGs and SPs are minimized whilst fulfilling a number of unit commitment constraints as well as generation scheduling constraints. Binary differential evolution along with priority list is applied for solving this problem. Numerical results of the system are comprehended for giving valued particulars for operative problem.

Nucleophilicity mediated interactions of ions with sensor: An anion induced BODIPY based chemodosimeter for sensing of CO2 gas

A BODIPY based chemodosimeter was designed and synthesized for detection of CO2 gas in presence of F−/CN− ion. The changes were observed in the absorption spectra of the probe and corresponding colour changes were clearly distinguished by naked eye. The mechanism of sensing was studied by NMR titration which reveals that unlike previous reports our probe can detect as well as trap CO2 through adduct formation. The sensing of CO2 was also extended to solid state through immobilizing the probe into hydrogel matrix as well as onto silica. Both hydrogel composite and silica loaded with the probe exhibit colour changes upon exposure to CO2. Also, the practical application of the probe was demonstrated through detection and estimation of dissolved CO2 in carbonated beverages. Moreover, the probe can detect F− and CN− through two different mechanisms governed by the nucleophilicity of the anion. The type of interaction of the probe with F− and CN− were elucidated with absorption and NMR study. Both the F− and CN− ions induced quenching of emission of the probe owing to activation of PET (Photo-induced Electron Transfer). The anion induced change in fluorescence intensity of the probe was also demonstrated with theoretical study. Moreover, the practical applicability of the probe for CN− sensing was established through sensing of CN− in 100% aqueous solution.

Lean NOx trap catalyst formulation for selective ammonia synthesis from captured NOx

In the Lean NOx Trap (LNT) technology, ammonia (NH3) occurs as reaction intermediate in conversion of trapped nitrogen oxides (NOx) to nitrogen gas (N2) using hydrogen gas (H2) reductant. The use of an LNT for synthesizing NH3 from NOx is potentially an attractive option for small-scale green NH3 production by converting locally produced NOx pollutant to an important chemical. In this work, it is investigated to what extent the product selectivity towards NH3 on the standard model catalyst Pt/BaO/Al2O3 can be maximized depending on reaction conditions for trapping and reducing NOx with H2 in the temperature range of 75–200 °C. The LNT catalyst preparation was varied by using Pt, Pd and bimetallic combinations, as well as different support materials, namely Al2O3, TiO2, ZrO2 and MgO. NOx adsorption and selectivity of captured NOx reduction to ammonia is discussed in terms of texture and the chemical nature of the support. The NH3 selectivity is influenced by the water vapor content in the gas feed. Storage of NOx in absence of water followed by reduction with hydrogen gas in presence of water vapor was found to be the most favorable operation mode of the LNT for NH3 formation. The NH3 selectivity reached 82% at 150 °C. Explanations for the role of water and in this catalytic chemistry are offered and its consequences for catalyst preparation are discussed. The optimum water content of the reacting gases is predicted to be strongly dependent on catalyst preparation.

Exploring porphyrins induced carbon nanocone TM-PICNC (TM = Sc2+, Ti2+, V2+, Cr2+, Fe2+, Co2+, Ni2+, Cu2+, and Zn2+) as a highly sensitive sensor for CO2 gas detection in presence O2 and H2O molecules: a computational study

This study investigated the adsorption of CO2 molecules on transition metal ions (TM) porphyrins induced carbon nanocone (TM-PICNC) (TM = Sc2+, Ti2+, V2+, Cr2+, Fe2+, Co2+, Ni2+, Cu2+, and Zn2+) using density functional theory (DFT) to determine the stabilities, energetic, structural, and electronic properties. The results showed that the CO2 molecule is adsorbed on TM-PICNC with adsorption energies ranging from 0.03 to −12.12 kcal/mol. The weak interactions of CO2 gas with Cr, Ni, Cu, and Zn-PICNC were observed, while strong adsorption was found on Sc, Ti, and V-PICNC. The Ti, V, and Cr-PCNC structures were shown to have a suitable energy gap (Eg) for sensing ability because of the effective and physical interaction between these structures and CO2 gas, leading to a short recovery time. DFT calculations also revealed that V-PCNC had a high %ΔEg (about %56.79) and hence high sensitivity to CO2 gas, making it a promising candidate for having good sensing ability to CO2 gas in presence of O2 and H2O gas.

Representative operating scenario selection with algebraic multi-grid clustering for integrated energy systems planning

Recent shifts towards higher renewable penetration in power systems, has resulted in increasing gas-fired generation capacity in systems without hydro or other fast responding alternatives, implying increased electricity and gas infrastructure interdependency. Furthermore, highly efficient combined heat and power (CHP) units lead to heat and electricity interdependency. It is crucial to consider these interdependencies in the expansion planning of energy systems for an effective and reliable investment planning and policy design. In this paper, the problem of integrated expansion planning of electricity, heat, and gas in presence of demand and wind uncertainty is addressed. Representative operating scenario selection with algebraic multi-grid clustering is used to model wind and demand uncertainties, and to address computational complexity of a central planning model. The simulation results on a modified IEEE-118 bus test system with a 14-node gas network shows that the algebraic multi-grid clustering outperforms the classical methods such as kmeans by following the benchmark case more closely.

Discovering the impact of targeted defects in SP-MOF for CO2 capture from flue gas in presence of humidity through computational modelling

The imperfections in crystalline porous solid materials through defects and further accelerating the separation performances of MOFs are growing interest in recent times. Herein, a novel class of [Cu(SiF6)(4,4′-bipyridine)2] square pillared (SP) material is used to analyse the impact of targeted defect amendment for CO2 capture from flue gas via specific force field-based molecular simulation. Additionally, the performances of CO2 separation from flue gas composition in the presence of humidity are more realistically predicted with the aid of a theoretically modelled breakthrough curve from their co-adsorption isotherms.

Challenges in the interpretation of gas core levels for the determination of gas-solid interactions within dielectric porous films by ambient pressure XPS

Near ambient pressure XPS in nitrogen atmosphere was utilized to investigate gas-solid interactions within porous SiO2 films ranging from 30 to 75 nm thickness. The films were differentiated in terms of porosity and roughness. The XPS N1s core levels of the N2 gas in presence of the SiO2 samples showed variations in width, binding energy and line shape. The width correlated with the surface charge induced in the dielectric films upon X-ray irradiation. The observed different binding energies observed for the N1s peak can only partly be associated with intrinsic work function differences between the samples, opening the possibility that the effect of physisorption at room temperature could be detected by a shift in the measured binding energy. However, the signals also show an increasing asymmetry with rising surface charge. This might be associated with the formation of vertical electrical gradients within the dielectric porous thin films, which complicates the assignment of binding energy positions to specific surface-related effects. With the support of Monte Carlo and first principles density functional theory calculations, the observed shifts were discussed in terms of the possible formation of transitory dipoles upon N2 physisorption within the porous SiO2 films.

The hydrate-based separation of hydrogen and ethylene from fluid catalytic cracking dry gas in presence of n-octyl-β-d-glucopyranoside

Hydrate-based gas separation (HBGS) needs a kinetic promoter to increase its economic value. The kinetic promoters for HBGS should have low foaming ability, high performance on increasing the conversion rate of the water into hydrate (RWH) and little thermodynamic inhibition on hydrate formation. However, no reported kinetic promoter meets all above requirements at same time. According to the experimental results in this work, n-octyl-β-d-glucopyranoside (OGP) met all those requirements of HBGS. For that reason, OGP was proposed as a new kinetic promoter for HBGS, and its effects on HBGS were revealed by investigating the HBGS of hydrogen and ethylene from fluid catalytic cracking dry gas in presence of OGP in this work. OGP enhanced the HBGS performance by increasing RWH from less than 64% to higher than 84%. By one-step separation, the hydrogen concentration was increased from 26.0 mol% to about 46.8 mol% while the ethylene concentration was increased from 52.0 mol% to about 74.4 mol%. The effect of the initial OGP concentration in liquid phase (wp,0) on HBGS increased with the increase in RWH, and the optimum wp,0 was 0.20 mass%. The processing capacity of the OGP solution in the HBGS was about 350 NL feed gas/L. OGP enhanced the promotion of increasing pressure on the HBGS performance. A new model was proposed to predict the thermodynamic equilibrium hydrate formation pressures of the experimental systems: the maximum relative deviation is 5.08% and the average relative deviation is 2.61%.

Synthesis of N-Bases from Primitive Earth Gases in presence and absence of Metal Ferrocyanides

The action of heat on Acetylene, Ammonia and Water vapour in presence and absence of metal ferrocyanides at 90±5°C under simulated sea beach conditions has been investigated for the plausible formation of nucleic acid bases. Paper chromatography (PC) and High-Performance Liquid Chromatography (HPLC) analysis of the reaction concentrate heated up to 200hrs revealed purine and pyrimidine bases viz. cytosine, uracil, adenine, thymine and hypoxanthine were formed and confirmed with the data of authentic samples.

Supramolecularly assembled isonicotinamide/reduced graphene oxide nanocomposite for room-temperature NO2 gas sensor

Herein, room-temperature NO 2 gas sensor based on supramolecularly assembled isonicotinamide–graphene oxide nanocomposite (Iso-rGO) and Iso-rGO/Carbon felt (CF) electrode was prepared and studied. The morphology of the synthesized Iso-rGO nanocomposite was studied by field emission scanning electron microscopy (SEM), which revealed the uniform coating of isonicotinamide over the surface of the composite. Further studies confirmed the supramolecular functionalization assembly of isonicotinamide onto the surface of GO. The prepared nanocomposite was used as functional electrode material to fabricate room-temperature NO 2 gas sensor. The fabricated electrode (Iso-rGO/CF) exhibited excellent reductive behavior of NO 2 gas at room-temperature. The fabricated sensor exhibited a linear range from 1–30 ppm and a low detection limit (LOD) of 1 ppm towards NO 2 gas. The NO 2 sensitivity of the Iso-rGO/CF electrode is well correlated with online gas chromatography which demonstrate high sensitivity and good stability for more than 30 days. The observed results revealed that the proposed Iso-rGO/CF electrode could be a suitable sensor electrode for the sensitive detection of gaseous NO 2 in the real samples. • Synthesis of supramolecularly assembled isonicotinamide/ reduced graphene oxide (Iso-rGO) nanocomposite. • Fabrication of room-temperature NO 2 gas sensor based on Iso-rGO nanocomposite. • The fabricated Iso-rGO/CF electrode based NO 2 sensor exhibited a linear dynamic range of 1–30 ppm and low limit of detection (LOD) of 1 ppm. • The developed sensor demonstrates good selectivity towards NO 2 gas in presence of other interfering gases such as CO 2 , acetone, N 2 O, SOx, Phenol and dichloromethane.

The one-dimensional Bose gas with strong two-body losses: the effect of the harmonic confinement

We study the dynamics of a one-dimensional Bose gas in presence of strong two-body losses. In this dissipative quantum Zeno regime, the gas fermionises and its dynamics can be described with a simple set of rate equations. Employing the local density approximation and a Boltzmann-like dynamical equation, the description is extended to take into account an external potential. We show that in the absence of confinement the population is depleted in an anomalous way and that the gas behaves as a low-temperature classical gas. The harmonic confinement accelerates the depopulation of the gas and introduces a novel decay regime, which we thoroughly characterise.

The Propagation of Hydromagnetic Cylindrical Shock Waves in Weak Magnetic Field, With A Self-Gravitating Gas

<p>The effects of overtaking disturbances behind the flow on the propagation of diverging cylindrical shock Waves through an ideal gas in presence of a magnetic field having =constant= and an Initial density distribution where is a constant, is the density at the plane / exes of symmetry: The analytical formula for flow variables representing both the position form viz; weak and strong cases at shock waves have been obtained. Their numerical estimates at permissible shock front locations have been obtained.</p> <p>There numerical estimates at permissible shock front location's have been Calculated and compared with earlier result describing in Free Propagation through figures. After inclusion of E.O.D. noted that there is no change at flow variable with parameters and . However, the trends of variation with propagation distance r, for shock strength, shock velocity and particle velocity are not change in case of weak shock with work Magnetic field<strong>(wswmf).</strong></p>

An improved correlation for gas release from nitride fuels

An improved correlation for gas release from nitride fuels is elaborated. Introducing empirical activation energies for migration of fission gases in presence of solid fission products and oxide impurities, it becomes possible to better reproduce existing experimental data sets for gas release in sodium and helium bonded rods. The suggested approach may assist in resolving the previously poorly understood dispersion in measured gas release for identical irradiation conditions.

Conductometric NOx sensor based on exfoliated two-dimensional layered MnPSe3

Nitrogen dioxide (NO2) and nitric oxide (NO) collectively called NOx are toxic gases which are emitted during combustion process. Selective detection of NOx at low concentration is essential for human health and environment monitoring. The present study has explored the use of 2D few-layer manganese phosphoselenide (MnPSe3) towards selective and reversible NOx (NO2 and NO) sensing under ambient conditions. Few layer MnPSe3 obtained by solvent exfoliation of bulk material is used as uniform thin film for NOx gas sensing. The sensor shows responses of 685% and 137% for the detection of 1 ppm of NO2 and NO gas respectively. The total NOx (sum of NO and NO2) at different ratios of the constituents can be detected as well. The response follows Langmuir-type behavior with high selectivity towards NOx-based gases in presence of H2, O2, CO, CO2 and C2H2. The sensor is completely reversible with fast response and recovery times under ambient conditions. Temperature dependent studies indicate that the sensor response increases upto a certain temperature and then decreases in presence of humidity. The effect of humidity is studied as well.

Deformation of the Fermi surface of a spinless two-dimensional electron gas in presence of an anisotropic Coulomb interaction potential

We consider the stability of the circular Fermi surface of a two-dimensional electron gas system against an elliptical deformation induced by an anisotropic Coulomb interaction potential. We use the jellium approximation for the neutralizing background and treat the electrons as fully spin-polarized (spinless) particles with a constant isotropic (effective) mass. The anisotropic Coulomb interaction potential considered in this work is inspired from studies of two-dimensional electron gas systems in the quantum Hall regime. We use a Hartree–Fock procedure to obtain analytical results for two special Fermi liquid quantum electronic phases. The first one corresponds to a system with circular Fermi surface while the second one corresponds to a liquid anisotropic phase with a specific elliptical deformation of the Fermi surface that gives rise to the lowest possible potential energy of the system. The results obtained suggest that, for the most general situations, neither of these two Fermi liquid phases represent the lowest energy state of the system within the framework of the family of states considered in this work. The lowest energy phase is one with an optimal elliptical deformation whose specific value is determined by a complex interplay of many factors including the density of the system.

Recent Advances in Plasma/Nanoparticles Treatments of Textile Fibers

A general review on natural and synthetic fabrics treatments with low-temperature plasma using various gases in presence of different types of nanoparticles is given. The effect of using plasma/nanoparticles on the surface morphology, physical and mechanical properties of the treated fabrics is declared. Using combined plasma and nanoparticles treatments show a noticeable effect and great enhancement on many properties of all textile fibers. Improvement of functional properties of textile materials is considered crucial to the textile industry. Dyeing and printing improvement could be achieved and it was found to depend on the types of plasma and nanoparticles used. Scanning electron microscopy showed that the surface characteristics of all fabrics were changed while the bulk properties were mainly maintained unchanged. Textile industries see a promising future for plasma/ nanoparticles technology, with the environmental and energy conservation benefits, in developing high-performance materials for the world market.

The hydrate-based gas separation of hydrogen and ethylene from fluid catalytic cracking dry gas in presence of Poly (sodium 4-styrenesulfonate)

The effects of the influential factors (initial promoter concentration in liquid phase, initial ratio of the volumes of gas to liquid (IFL) and temperature) on the hydrate-based gas separation (HBGS) and their relationships with the conversion rate of the water into hydrate (RHW) were experimentally investigated. Poly (sodium 4-styrenesulfonate) (PSS) was first-time used in HBGS. After one-stage HBGS, hydrogen can be concentrated from 26.0 mol% to more than 45.9 mol% in the residual gas and ethylene can be concentrated from 52.0 mol% to more than 72.6 mol% in the dissociated gas. PSS had low foaming ability, it effectively decreased the gas–liquid interfacial tension and had little effect on the thermodynamic equilibrium hydrate formation condition. PSS had little effect on the separation performance when RHW was about 13% whereas it significantly improved the separation performance when RHW was higher than 59%, the optimum PSS concentration was 0.2 mass%. In the separation in presence of PSS, the increase in IFL did not cause a decrease in the separation performance until IFL increased to more than 300 NL/L. The positive effect of decreasing temperature on HBGS decreased with the increase in RHW, and it disappeared in the HBGS using pure water when RHW was higher than 57.0% whereas it still existed in the HBGS using PSS solution when RHW was 67.8%. An innovative model was established to predict the equilibrium hydrate formation pressure, and the average relative deviation was 2.6%, with the maximum relative deviation being 5.5%.

Ultracold gases in presence of time-dependent synthetic gauge field

We analyze the effect of a time-dependent synthetic magnetic field on the Mott-Insulating (MI) to superfluid (SF) phase transition of a system of bosons via a site decoupling mean-field approach. The synthetic field is incorporated through Peierls coupling that induces a phase shift in the hopping matrix of the Bose-Hubbard model (BHM). We observe that the behavior of critical hopping strength, Jc, vary differently for different time-dependent synthetic fields. The Mott insulating lobe either stabilizes or contracts depending on the nature of the tuning of the time-dependent synthetic field. Also the inclusion of time in the synthetic field destroys the lattice periodicity, however with proper tuning of the time variation of the gauge field, the periodicity can be restored back. Hence the periodicity of the one-dimensional superfluid order parameter is very sensitive to the variation of the time-dependent field. Further, the order parameter either becomes site dependent or independent depending on the nature of the tuning of the these fields. The time-dependent synthetic magnetic field also induces an asymmetry in the discrete energy spectrum of the system which is also clear from the vanishing ‘Butterfly’ pattern of the single particle energy spectrum.

Isothermal Motion of Hydromagnetic Cylindrical Shock Waves in Self Gravitating Rotating Gas

In this paper the Chisnell2 Chester1 Whitham3 (CCW1-3) method has been used to study the isothermal propagation of cylindrical hydromagnetic diverging shock waves in self gravitating rotating gas in presence of constant axial magnetic field. Assuming density decreasing atmosphere and exploring magnetic field as weak and strong, the analytical expressions have been derived for both weak and strong shocks and finally the effects of overtaking disturbances behind the flow on the motion of shock have also been included