Methanol Vapor Research Articles

Thermodynamics of the interaction between Keplerate-type polyoxometalate {Mo72Fe30} and vitamin B1

The thermodynamics of the interaction between the nanocluster iron-molybdenum Keplerate-type polyoxometalate {Mo72Fe30} and thiamine hydrochloride (vitamin B1) was studied. This system is considered as a model for new types of targeted drug delivery systems. We evaluated the thermodynamic characteristics of the interaction between {Mo72Fe30} and B1 using experimentally measured sorption parameters for methanol vapour and the enthalpy of the interaction with liquid methanol for the initial compounds ({Mo72Fe30}, B1) and the {Mo72Fe30}+B1 conjugate. It was determined that the energetically unfavourable interaction of the components is due to entropy's predominant contribution to the Gibbs energy. Using X-ray analysis, it was shown that the increase in entropy is associated with one of the components (thiamine hydrochloride) losing its crystal structure.

π-Electronic Coassembled Microflake Sensors with Förster Resonance Energy Transfer Enhanced Discrimination of Methanol and Ethanol.

In the field of fluorescence-based gas sensing, it is very difficult to realize the distinction of the molecules with similar chemical properties and slight structural differences (e.g., methanol and ethanol). Herein, we fabricated coassemblies of energy-donor molecule 1 (M1) and energy-acceptor molecule 2 (M2) with different molar ratios. These materials can selectively differentiate methanol and ethanol by regulating the distance of exciton migration of donor M1 by embedding energy-acceptor M2. More importantly, methanol can also be detected from the mixture vapors of methanol and ethanol. These results provide a new approach for developing fluorescence sensors that are highly sensitive to molecules with very small difference in the chemical structures.

Methanol-induced luminescence vapochromism based on a Sb3+-doped organic indium halide hybrid

Ion doping has been demonstrated as a practical approach to achieving highly efficient luminescence in both inorganic phosphors and organic-inorganic hybrids. The as-formed doping species show great potential in optoelectronic applications due to their high photoluminescence quantum yield (PLQY) and excellent stability. Herein, we report highly emissive Sb3+-doped indium halides (C6H18N2)InCl5·H2O:Sb (C6H18N22+ = N,N,N′,N′-tetramethylethane-1,2-diammonium) prepared by solution evaporation methods with an emission that peaked at 565 nm and a PLQY of 74.6%. Photophysical characterizations and density functional theory computational studies verify the broadband emission originating from a self-trapped exciton. Interestingly, a drastic red shift of the emission peak from 565 to 663 nm with yellow luminescence turning to red is observed once the (C6H18N2)InCl5·H2O:Sb hybrid is exposed to methanol vapor. Moreover, when the methanol-exposed hybrid is put in air, the emission reverts to 565 nm in several minutes. Single-crystal X-ray diffraction studies show a subsequent structure distortion upon the coordination of methanol to the Sb(III) center, which is responsible for the drastic red shift of the emission. Encouragingly, we found that (C6H18N2)InCl5·H2O:Sb exhibits a specific response to methanol vapor after screening a series of volatile organic compounds with different polarities. Besides, a negligible change of the emission intensity is observed after several cycles of uptaking and releasing methanol. The high fatigue resistance and specific solvent response of the Sb3+-doped indium halide make it a very promising methanol detector.

Water Vapor Adsorption Capacity Loss of Molecular Sieves 4A, 5A, and 13X Resulting from Methanol and Heptane Exposure.

Zeolite-based molecular sieves are applied in industrial dehydration units for their high water uptake capacities and extremely low equilibrium pressure of water vapor. During their operational life, they tend to lose their water vapor adsorption capacity slowly. To optimize the usage of molecular sieves in dryer units, it is vital to understand the mechanism(s) leading to deactivation. In this work, the capacity loss was studied by exposing LTA- and FAU-type zeolites to methanol and heptane vapors under relatively harsh conditions using repetitive adsorption/regeneration cycles. A simple microflow unit was designed and used for the deactivation experiments. The water vapor adsorption capacity of the resulting samples was measured using a gravimetric analyzer. In addition, they were characterized by classic XRD, 13C NMR, and TGA techniques. The crystallinity of fresh and spent zeolite XRD patterns was not drastically affected even after exposure to the contaminants. It was found that methanol easily gave rise to a severe loss of water vapor adsorption capacity, much more so than heptane. Water vapor uptake in the methanol exposed samples is ∼50% lower than that for the fresh zeolites. This is attributed to nonvolatile, residual hydrocarbons.

A solvent driven dual responsive actuator based on MOF/polymer composite

The dual-responsive actuator which response to external stimulus with deformation and discoloration simultaneously gained considerable attention for their application such as soft robot. Inspired by the soft MOF (Metal-Organic framework)/polymer solvent driven actuator based on flexible MOF which can expand/contract with the gain and loss of solvent molecules, and also the structural color films with inverted opal structure, a monolayer solvent driven dual-responsive actuator based on MOF/polymer composite, namely MIL-88A/CB(carbon black)/PVDF, has been successfully prepared through the casting and etching method. The MIL-88A/CB/PVDF film can respond to the change of ambient solvent atmosphere with the whole or part of the composite film exhibiting a synergistic coupling of the surface color change and the out-of-plane motion under the driven of the methanol vapor. The bending deformation of 730° can be quickly achieved in about 1.66 s and the color change covers a wide range with three high saturation color (red, green and blue) which can be observed with different view angles. In addition, some simple devices including smart flower, inchworm walker, and visual gas sensor were designed based on this material. This work is the first example which apply MOF to solvent driven dual response materials with simultaneous deformation and discoloration, which opens up a new application field for MOF, and also provides a new perspective for the preparation of smart materials.

Solvent-Mediated Proton-Transfer Catalysis of the Gas-Phase Isomerization of Ciprofloxacin Protomers.

Understanding how neutral molecules become protonated during positive-ion electrospray ionization (ESI) mass spectrometry is critically important to ensure analytes can be efficiently ionized, detected, and unambiguously identified. The ESI solvent is one of several parameters that can alter the dominant site of protonation in polyfunctional molecules and thus, in turn, can significantly change the collision-induced dissociation (CID) mass spectra relied upon for compound identification. Ciprofloxacin─a common fluoroquinolone antibiotic─is one such example whereby positive-ion ESI can result in gas-phase [M + H]+ ions protonated at either the keto-oxygen or the piperazine-nitrogen. Here, we demonstrate that these protonation isomers (or protomers) of ciprofloxacin can be resolved by differential ion mobility spectrometry and give rise to distinctive CID mass spectra following both charge-directed and charge-remote mechanisms. Interaction of mobility-selected protomers with methanol vapor (added via the throttle gas supply) was found to irreversibly convert the piperazine N-protomer to the keto-O-protomer. This methanol-mediated proton-transport catalysis is driven by the overall exothermicity of the reaction, which is computed to favor the O-protomer by 93 kJ mol-1 (in the gas phase). Conversely, gas phase interactions of mobility-selected ions with acetonitrile vapor selectively depletes the N-protomer ion signal as formation of stable [M + H + CH3CN]+ cluster ions skews the apparent protomer population ratio, as the O-protomer is unaffected. These findings provide a mechanistic basis for tuning protomer populations to ensure faithful characterization of multifunctional molecules by tandem mass spectrometry.

IR SPECTRA STUDY: ADVANTAGES OF METHANOL VAPOR FEEDING FOR NAFION® MEMBRANE STRUCTURE

This paper presents the IR-spectroscopy investigation of interaction between polymer protonconducting membranes (Nafion® brand) and various solvents. The solvent effect on the formed membrane structure is determined. The advantages of saturating membranes with methanol vapors over dipping into water/water-methanol mixture for membrane properties as a solid polymer electrolyte in the fuel cell are shown. An original method of feeding methanol vapors to a fuel cell by a hydrogen flow is proposed. Keywords: membrane, solid polymer el

Selective detection of methanol vapour from a multicomponent gas mixture using a CNPs/ZnO@ZIF-8 based room temperature solid-state sensor.

Methanol vapour is harmful to human health if it is inhaled, swallowed, or absorbed through the skin. Solid-state gas sensors are a promising system for the detection of volatile organic compounds, unfortunately, they can have poor gas selectivity, low sensitivity, an inferior limit of detection (LOD), sensitivity towards humidity, and a need to operate at higher temperatures. A novel solid-state gas sensor was assembled using carbon nanoparticles (CNPs), prepared from a simple pyrolysis reaction, and zinc oxide@zeolitic imidazolate framework-8 nanorods (ZnO@ZIF-8 nanorods), synthesised using a hydrothermal method. The nanomaterials were characterized using scanning electron microscopy, transmission electron microscopy, powder X-ray diffraction, X-ray photoelectron spectroscopy Raman spectroscopy, and Fourier transform infrared spectroscopy. The ZnO@ZIF-8 nanorods were inactive as a sensor, the CNPs showed some sensor activity, and the CNPs/ZnO@ZIF-8 nanorod composite performed as a viable solid-state sensor. The mass ratio of ZnO@ZIF-8 nanorods within the CNPs/ZnO@ZIF-8 nanorod composite was varied to investigate selectivity and sensitivity for the detection of ethanol, 2-propanol, acetone, ethyl acetate, chloroform, and methanol vapours. The assembled sensor composed of the CNPs/ZnO@ZIF-8 nanorod composite with a mass ratio of 1.5 : 6 showed improved gas sensing properties in the detection of methanol vapour with a LOD of 60 ppb. The sensor is insensitive to humidity and the methanol vapour sensitivity was found to be 0.51 Ω ppm−1 when detected at room temperature.

Bi-hierarchical porous Pt microspheres grown on Ti wire with TiO2nanotubes layer for selective alcohol sensing

ABSTRACTThis study focuses on the synthesis of bi-hierarchical porous Pt microspheres directly on titania nanotube arrays grown on a Ti wire for their application as a one-electrode selective alcohol sensor. We evaluate the synthesis conditions, morphology, structure of the obtained material using scanning, transmission electron microscopy and electron diffraction. The sensor performance is assessed in a one-electrode configuration, using thermocycling protocols both to heat and acquire a signal that we further process with a machine learning algorithm for selective determination of alcohols. We found that reduction of Pt precursor by formic acid facilitates the appearance of quasi-1D Pt structures without using any surfactant. High excess of formic acid yields the formation of quasi-dendritic Pt structures with the overall morphology of a sphere and channels whose diameter remains one of the TiO2 nanotubes. Our data suggest the growth of Pt spheres to be diffusion controlled with constant or decreasing nucleation rate that should include assembling of Pt nanorods. The fabricated sensors based on the synthesized structures show a chemiresistive response to methanol, ethanol and isopropanol vapors in the mixture with air, which we selectively determine using only one sensor.

A Novel Gas Sensor Based on Activated Charcoal and Polyaniline Composites for Selective Sensing of Methanol Vapors

A Novel Gas Sensor Based on Activated Charcoal and Polyaniline Composites for Selective Sensing of Methanol Vapors

High-sensitivity room temperature p-doped and undoped GaN thin film resistive gas sensor

The behaviour and performance of p-doped GaN and undoped GaN thin film in the presence of methanol gas were studied. GaN thin films were grown using metal organic chemical vapour deposition (MOCVD), which were then fabricated into resistive sensors. Gas-sensing characterisation with the in-house gas chamber demonstrates that the resistive sensors based on undoped and p-doped GaN exhibit high sensitivity and fast response to methanol vapour in less than a minute, as well as excellent stability in room temperature operations. Without high temperature measurements, both undoped and p-doped GaN resistive sensors exhibit significant resistance variation and response over time when exposed to methanol, albeit with distinct properties. Here we demonstrate the comparison between the two and their sensing capabilities of both p-doped GaN and undoped GaN thin film resistive sensors.

Methanol sensing characteristics in undoped and (Zn, Mn) doped Fe(phen)2(NCS)2 spin-crossover thin films

The methanol sensing properties of spin-crossover (SCO) complex Fe(phen)2(NCS)2 thin, as well as those of thin films doped with Zn or Mn are demonstrated here. The synchrotron x-ray diffraction (SXRD) data clearly confirms the crystal structure of the SCO complex. The microstructure studied by transmission electron microscopy (TEM) clearly shows the formation of cuboid-shaped growth of nanocrystals and is similar for all the samples. The optical photographs of the samples show an evident change in color from reddish-purple color to pink upon exposure to methanol vapor. The optical absorption band (∼540 nm) in the presence of methanol of the SCO films is shifted to a longer wavelength with exposure time. The methanol sensitivity of SCO films is further investigated using electrical resistance measurements, which reveal that the response differs between Zn and Mn doped films and undoped ones. The difference in electronegativity of metals plausibly alters the polaron hopping transport in the SCO films and explains the observed variation of resistance with methanol exposure. The data suggest that using spin-crossover materials may be pretty important in designing smart sensors in the future.

Wearable Motion Smartsensors Self-Powered by Core-Shell Au@Pt Methanol Fuel Cells.

A wearable self-powered sensor is a promising frontier in recent flexible electronic devices. In this work, a wearable fuel cell (FC)-type self-powering motion smartsensor has been fabricated, particularly in choosing methanol vapor as a target fuel for the first time. The core-shell structure of Pt@Au/N-rGO and the porous carbon network act as methanol oxidation and oxygen reduction reaction catalysts, with a highly conductive alkaline hydrogel as a solid-state electrolyte. As a result, a wearable FC for a self-powered sensing system demonstrates excellent sensing performance toward 2-20% (v/v) methanol vapor with a maximum power density of 2.26 μW cm-1 and good mechanical behaviors during the bending or twisting process. Significantly, this wearable FC device could power strain sensors of human motion, and real-time signals can be easily remotely detected via a cellphone. With attractive biocompatibility and self-powering performance, wearable FCs for a self-powering system would provide new opportunities for next-generation flexible smartsensing electronics and initiate a developed self-powering platform in future practical application of wearable smart monitoring.

Electrical conductivity based ammonia, methanol and acetone vapour sensing studies on newly synthesized polythiophene/molybdenum oxide nanocomposite

Polythiophene (PTh) and polythiophene/molybdenum oxide nanocomposites (PTh/MoO 3 ) were synthesized by an in-situ chemical oxidative method. The successful synthesis of both the materials was confirmed by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The thermal stability of the materials was examined in terms of conductivity retention under isothermal and cyclic aging conditions. PTh/MoO 3 showed much greater conductivity retention (i.e., thermal stability) than pristine PTh under both conditions. PTh/MoO 3 showed 18.22 times greater electrical conductivity than pristine PTh at room temperature. The sensing properties of PTh and PTh/MoO 3 were tested against ammonia, methanol, and acetone vapour at room temperature. The percent sensing response (%) of the PTh/MoO 3 sensor was found to be about 1.64, 1.44, and 1.48 times greater than the PTh sensor towards ammonia, methanol, and acetone at 1 M, respectively. The PTh/MoO 3 sensor showed 1.48, 1.60, and 1.72 times greater reproducibility than the PTh-based sensor towards ammonia, methanol, and acetone, respectively. Thus, at a 1 M concentration of ammonia, methanol, and acetone, the PTh/MoO 3 sensor performed much better than the PTh sensor in terms of the sensing response and reproducibility. Furthermore, the PTh/MoO 3 sensor showed a maximum and minimum sensing response towards ammonia and acetone, respectively.

The Effect of Current Density on the Properties of Porous Silicon Gas Sensor for Ethanol and Methanol Vapour Detection

In this paper, Gas sensors for ethanol and methanol were created utilizing porous silicon (PSi).n-type silicon was employed for all PSi samples, photo-electrochemical etching technique (PECE) was used to prepare porous surface. The intensity of the three etchings current densities was 12, 24 and 30 mA / cm2, with 40% hydrofluoric acid concentration (HF) and a time of etching 10 minutes. Porous silicon (100) has been strictly studied by the structure and formation of surface bonding of the PSi layer; the structural properties, morphological characteristics, pore diameter, and roughness were described using X-ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM). All PSi samples were applied as a sensor for ethanol and methanol at room temperature. The results showed that the best sensitivity of PSi was to ethanol gas compared to methane under the same used conditions at etching current density 30mA/cm2, reaching about 1.809 at a concentration of 500 ppm. From these results, the PSi layers act as high-quality, low-cost gas sensors. It can be used as a replacement for expensive material that is used as gas sensors, which operate at low temperatures, including room temperature. The interest in this material is due to study the effect of extremely high surface to volume ratio (increasing surface area), and easy manufactured and compatibility with modern silicon microelectronics manufacturing technologies.

Numerical analysis of the effect of swirl angle and fuel equivalence ratio on the methanol combustion characteristics in a swirl burner

The outstanding advantages of methanol such as low pollutant emissions of nitrogen oxides (NOx) and carbon monoxide (CO) make it a promising clean-burning fuel. Despite, the latent heat of vaporization of methanol is 3.70 times that of gasoline, the low heating value of methanol is one of the most critical barriers to its effective utilization in industrial applications. Thus, the methanol burner needs to be effectively designed to determine the desired combustion characteristics and the optimal design of this type of clean burner. Hence, this study presents a computational fluid dynamic analysis on the combustion characteristics of a methanol swirling burner with two layers of swirling blades. A particular focus of this study is emphasized on the effects of different swirling blade angles (45°+45°, 60°+60°, and 45°+60°) and various equivalence ratios (0.5, 0.75, 1.0, 1.25, and 1.75) on the combustion characteristics and pollutants formation of the swirl burner. The velocity and temperature profiles, combustion characteristics, and concentrations of major combustion species are analyzed in detail. The results show that the blade angle arrangement of 45°+ 60° exhibits the best combustion characteristics in comparison with the other blade angle arrangements. It is also found that the BA3 with an equivalent ratio in the range of 1.0–1.25 shows the best performance in the emissions of NOx and CO compared with other combinations of swirling blade arrangements and equivalence ratios. More specifically, the optimal equivalence ratio ranges from 1.0 to 1.25 at which the NOx and CO emissions are measured to be 27.0 and 11.0 mg/m3, respectively.

Organic compound gas detector based on polylactic acid/poly (styrene‐co‐acrylonitrile)/multi‐walled carbon nanotube blend composite with co‐continuous microstructure

AbstractA conductive polymer composite (CPC) based on polylactic acid (PLA)/poly (styrene‐co‐acrylonitrile) (SAN)/multi‐walled carbon nanotubes (MWNT) blend was prepared and used as a sensitive layer for detecting methanol, ethanol, toluene, and water vapor. The response behavior of polymer blend nanocomposite in comparison with PLA‐MWNT and SAN‐MWNT sensitive layers was studied as well as the influence of solution blending on the morphology, electrical behavior, and performance parameters of prepared sensitive layers. The scanning electron microscopy micrograph results showed that the PLA/SAN solution blended with a 50/50 wt% ratio had formed the co‐continuous morphology. In addition, the electrical conductivity investigation revealed that the percolation threshold of sensitive layers decreased from 1.5 vol%, related to PLA‐MWNT, to 0.8 vol%, related PLA/SAN blend nanocomposite. Thermodynamic investigation revealed that, in the solution blended conductive composites, MWNTs are preferentially localized in the PLA phase. The relative response (Rrel) of blended conductive composite, in comparison with PLA‐MWNT, was increased toward ethanol and toluene vapor while it was decreased against the methanol vapor. The sensitivity behavior of polymer blend composite was investigated based on the double percolated conductive network as well as the thermodynamic parameters such as Flory‐Huggins interaction parameter and solubility parameters.

Desolvation–Solvation-Induced Reversible On–Off Switching of Two Memory Channels in a Cobalt(II) Coordination Polymer: Overlay of Spin Crossover and Structural Phase Transition

Desolvation–Solvation-Induced Reversible On–Off Switching of Two Memory Channels in a Cobalt(II) Coordination Polymer: Overlay of Spin Crossover and Structural Phase Transition

Performance evaluation of a trickling bioreactor treating methanol vapor under one- and two-liquid phase conditions

This study compared the performance of a trickling bioreactor (TBR) for methanol removal with and without the addition of silicone oil as a non-aqueous phase. Due to an adaptation process based on activated sludge, the acclimation period was as short as 16 days. First, TBR was run under one-liquid phase (OLP) condition at empty bed gas residence time (EBRT) of 120 s, while methanol inlet concentration varied from 0.25 to 15.1 g m −3 . The results showed that OLP-TBR could be a promising approach when facing with methanol shock loads with average removal efficiencies (REs) over 80%. For OLP operation, the maximum elimination capacity (EC) was 411 g m −3 h −1 at a methanol inlet loading rate (ILRs) of 453 g m −3 h −1 . Then, silicone oil (10% v/v ) was added to TBR to provide two-liquid phase (TLP) condition, under methanol inlet concentrations of 0.55-9.2 g m −3 and two different EBRTs of 120 and 60 s. For the TLP operation, a maximum EC of 416 g m −3 h −1 was obtained for an ILR of 474 g m −3 h −1 under EBRT of 60 s. The addition of silicone oil negatively affected the TBR performance, particularly for methanol inlet concentrations higher than 5 g m −3 . Based on 16S rDNA analysis, Citrobacter koseri LMG 5519(T), Leifsonia shinshuensis JCM 10591(T), and Pandoraea pnomenusa DSM 16536(T) were identified as the methanol degrading species. • Methanol removal in one and two-liquid phase O/TLP-TBRs was studied. • Maximum elimination capacity (EC) was 411 g m -3 h -1 in OLP-TBR. • TLP operation slightly decreased TBR performance at inlet concentrations> 5 g m -3 . • Dominant bacteria in TBR was identified by 16S rDNA analysis. • Methanol mineralization to CO 2 decreased in TLP-TBR with more biomass formation.

Design and synthesis of new conjugated copolymer for methanol sensing application

A conjugated copolymer comprised of aniline and pyrrole was synthesized by oxidative polymerization technique and the copolymer/ZnO nanocomposite thin films were prepared. The composite showed good sensing towards methanol vapours at room temperature. Composite showed faster response and good recovery on exposure to methanol vapours. The composite showed enhanced sensing response for methanol, higher than the pure polymer at room temperature. The nanocomposite exhibited excellent reproducibility, reversibility and with the highest selectivity of 0.1168 towards 100 ppm of methanol vapour. The research finding indicated that this polymer nanocomposite may be a potential candidate as methanol sensor.