Ketone Vapors Research Articles

Organic field-effect transistors with density of states modified by polymer-enhanced solvent vapor annealing

Solvent vapor annealing (SVA) is a post-fabrication process commonly utilized to reduce the structural or energetic disorder of organic semiconductor. In this work, pentacene organic field-effect transistors were treated by different solvent vapors. Methyl ethyl ketone (MEK) vapor was found to substantially improve device performance. The threshold voltage was lowered to be just −0.2 V and the subthreshold swing was steep at 200 mV/dec. Such improvements were interpreted in terms of the density of states. Quantitative analyses indicated that the SVA with MEK reshaped the density of states of the pentacene film; in particular, the localized tail states decreased considerably. Our finding suggests that our SVA method can repair water-induced defects in grain boundaries, which commonly has a negative effect on carrier transport, i.e., lessening charge localization in deep traps and thus ameliorating charge transport in electron devices. Therefore, polymer-enhanced SVA is a powerful post-fabrication technique to manufacturing high-performance organic devices.

Fabrication of a Bending-Insensitive In-Plane Strain Sensor from a Reversible Cross-Linker-Functionalized Silicone Polymer.

A reversibly cross-linkable and transparent polymer featuring stretchability and thermal healability is prepared by introducing Diels-Alder (DA)-reactive moieties into polydimethylsiloxane (PDMS), namely, a healable PDMS (h-PDMS). Inspired by the fact that retro-DA reactions occur even at low temperatures (albeit at a low rate), we maximize the effectiveness of small reactant products, demonstrating that self-healing and self-integration realized by 1-3 min exposure of cured h-PDMS to methyl ethyl ketone (MEK) vapor is more efficient than that achieved by direct sample heating at high temperatures. This technology is first used to uniformly transfer Ag nanowires (Ag NWs) formed on a temporary substrate to the h-PDMS surface, and further MEK vapor treatment allows the transferred NWs to be impregnated below the h-PDMS surface to afford an in-plane strain sensor. Most importantly, the developed method is used to perfectly integrate two identical Ag NW/h-PDMS films and thus place NWs on a neutral plane. Consequently, because of the unique structure in which a percolated network of AgNWs is formed on the interface where the two identical h-PDMS films are chemically integrated, the fabricated sensor is transparent, self-healable, stretchable, and insensitive to bending but sensitively responds to in-plane strain induced by lateral deformation.

Dynamic adsorption–desorption of methyl ethyl ketone on MCM-41 and SBA-15 decorated with thermally activated polymers

Three series of mesoporous adsorbents designed for removal of methyl ethyl ketone vapor (MEK) were synthesized: MCM-41 was decorated with various amounts of novolac resin (Nov) and polyacrylonitrile (PAN), while SBA-15 was modified with PAN. The composites were thermally activated towards an enhancement of MEK adsorption capacity and tested in a fixed bed adsorber. Structural features of parent silicas were investigated by XRD, while textural parameters of the composites were studied by low-temperature nitrogen adsorption. A surface composition was examined by DRIFT and XPS. It was found that decoration of the silica surface with small amounts of PAN improved the monolayer adsorption capacity. The MEK breakthrough curves and desorption profiles were employed for calculation of the monolayer capacity and total pore volume (VtotalMEK). The VtotalMEK for the materials with smaller pores (MCM-41) were comparable to those determined by nitrogen adsorption, whereas respective values for the solids with larger pores (SBA-15) were underestimated. The mechanism of adsorption of MEK onto the adsorbents was elucidated. The MEK molecules were adsorbed solely in the form of keto tautomer. The enhanced MEK adsorption capacity came from the beneficial textural features of the support and the presence of a ladder-type PAN structure containing O-groups.

Elimination of ketone vapors by adsorption on spherical MCM-41 and MCM-48 silicas decorated with thermally activated poly(furfuryl alcohol)

Spherical MCM-41 and MCM-48 silicas with different arrangements of mesopores were synthesized in a water–alcohol solution of surfactant by the hard-templating method. The pore structure and morphology of the obtained materials were confirmed by powder X-ray diffraction (XRD), low-temperature adsorption of nitrogen and scanning electron microscopy (SEM). The surface of mesoporous silicas was decorated with small amounts of poly(furfuryl alcohol) (PFA), which was introduced by the precipitation polymerization and subsequently thermally activated at 523 K to form stable CO surface species detected by FTIR spectroscopy. The adsorption capacity of the PFA/silica composites in the elimination of various ketone (acetone, methyl-ethyl ketone and methyl-isobutyl ketone) vapors was compared to the effectiveness of pristine silicas. It was found that the modification of silicas by thermally degraded PFA enhanced their adsorption capacity. This effect was attributed to the appearance of another type of surface centers (namely carbonyl groups), which beside silanols interact with ketone molecules via hydrogen bonds. DRIFT spectra showed that a ketone molecule is bonded on silanol species in its keto form, whereas on carbonyl functionalities in enol one.

Effect of Transition Metals on the Electrical Conductivity Response of dPPV/Zeolite Y Composites toward Ketone Vapors

ABSTRACTDoped poly(p‐phenylene vinylene) (dPPV) is mixed with modified zeolite Y to improve the selective and sensitive response of zeolite Y toward three different ketone vapors (acetone, methyl ethyl ketone, and methyl iso‐butyl ketone), which are known as the toxic components. Zeolite Y (Si/Al 5.1, Na+) or NaY is ion exchanged with transition cations, Cu2+, Ni2+, and Fe2+, at 80% cation exchanged to prepare 80CuNaY, 80NiNaY, and 80FeNaY. In this work, the effects of transition cations, ketone vapor type, and ketone vapor concentration are systematically investigated. The highest electrical conductivity response and sensitivity toward acetone vapor at the vapor concentration of 30,000 ppm is obtained with 80CuNaY, whereas 80FeNaY shows the lowest values due to the electrostatic interaction between the zeolite framework and the cation. dPPV is mixed with 80CuNaY and exposed to the three ketone vapors. The electrical conductivity response and sensitivity of the composites toward acetone exhibits the highest values, whereas with MIBK they show the lowest value. After mixing of 80CuNaY with dPPV, the minimum vapor concentration toward acetone vapor decreases from 9 to 5 ppm. The response of the composite is irreversible as evidenced by Fourier transform infrared and atomic force microscopy techniques.

Effective sensing of RDX via instant and selective detection of ketone vapors

Sensing a cyclic ketone frequently used as a solvent in the production of plastic explosives allows us to rapidly and effectively detect RDX. We explain the effects of the electron and energy transfer processes on the fluorescence response of a sensory material in this study.

Sensitive and Selective Responses of Poly(Para-Phenylene Vinylene)/Zeolite Y-Based Sensors Toward Ketone Vapors

Poly (p-phenylene vinylene) doped with H2SO4 is mixed into zeolite Y matriced to improve the electrical conductivity responses toward ketone vapors. The effect of cation type, cation concentration, and ketone vapor type on the electrical conductivity response toward ketone vapors of dPPV_zeolite Y composites is investigated. The sensitivities of the composites increase linearly with increasing surface area and decreasing cationic radius of the cation in zeolite Y. The highest sensitivity is obtained with the dPPV_[90] Y when exposed to acetone, whereas in MIBK shows the lowest sensitivity The interactions between the ketone molecules and the composites are investigated though the FTIR.

Poly(p-phenylene vilnylene)/zeolite Y composite as a ketone vapors sensor: effect of alkaline cation

This work is an attempt to improve the selectivity and sensitivity response of zeolite Y towards 3 different types of ketone vapors (acetone, MEK and MIBK) which are known to be toxic and flammable substances. The effects of cation type, cation concentration, ketone vapor type, and cyclic interval were investigated. Three different cations were exchanged in zeolite Y at 50 % mole: NaY, 50KNaY, 50MgNaY and 50CaNaY for the zeolite Y at a fixed Si/Al ratio of 5.1. 50KNaY sample exhibits the highest electrical conductivity sensitivity. This arises from the electrostatic interaction between the cation and the zeolite framework, which affects the adsorption properties of zeolite. The dPPV was mixed with 80KNaY matrix at 10 % v/v and was exposed to 3 different ketone vapors. The highest electrical conductivity sensitivity belongs to the acetone exposure, whereas the MIBK exposure shows the lowest value, as a result of the smaller acetone size. The sensitivity of the composite is higher than that of pure zeolite Y by an order magnitude. For the cyclic interval, the electrical conductivity response decreases with increasing number of the interval due to the interaction between the active site and ketone vapors. The response of samples is irreversible as evidenced by FTIR.

Thermal transformation of polyacrylonitrile deposited on SBA-15 type silica

Thermogravimetry, diffuse reflectance infrared Fourier transform spectroscopy, and X-ray photoelectron spectroscopy (XPS) were used for the studying of thermally induced structural changes of polyacrylonitrile (PAN) deposited on the surface of SBA-15 type mesoporous silica. Polymer was introduced onto the support by the precipitation polymerization of acrylonitrile in aqueous suspension of SBA-15. Low temperature transformation (to 723 K) of the deposited PAN was analyzed. It was found that at about 523 K, exothermic cyclization of polymer chains to the so-called ladder form of PAN occurred. However, the total cyclization of PAN required higher carbonization temperatures, at which gradual dehydrogenation followed by graphitization was initiated. XPS revealed that the cyclic form of PAN and a relatively large amount of carbonyl species, formed during the carbonization of the PAN/SBA-15 composite at 623 K, were responsible for the high sorption capacity in the methyl–ethyl ketone (MEK) vapor elimination. The efficiency in the MEK adsorption was also influenced by the content of PAN-derived carbon deposited on the SBA-15 surface.

Removal of benzene and methyl ethyl ketone vapor: Comparison of hypercrosslinked polymeric adsorbent with activated carbon

A novel hypercrosslinked polymeric adsorbent (HY-1) with high surface area and specific bimodal pore size distribution in the regions of micropore (0.5–2.0 nm) and meso-macropore (30–70 nm) was prepared. Adsorption properties of benzene and methyl ethyl ketone (MEK) vapors onto HY-1 were investigated and compared with a commercial microporous activated carbon (m-GAC). The equilibrium adsorption data showed that the adsorption capacities of benzene and MEK on HY-1 were larger than those of m-GAC at the higher relative pressure. The Dubinin–Radushkevich (D–R) equation was found to fit the experimental data well. The isosteric enthalpy of adsorption for benzene and MEK were calculated. The m-GAC exhibited much higher values of Δ H st for the VOCs than HY-1 at the whole loading studied, which can lead to significant temperature rises during the adsorption step. The results of dynamic experiments revealed that HY-1 had a good dynamic adsorption capacity with a longer breakthrough time and shorter length of mass transfer zone due to its specific bimodal property. Therefore, HY-1 will be a particularly efficient and competitive adsorbent for VOCs recovery, especially at medium-high concentrations.

Removal of methyl–ethyl ketone vapour on polyacrylonitrile-derived carbon/mesoporous silica nanocomposite adsorbents

Mesoporous silica supports (MCM-41, SBA-15 and silica gel) were modified by the introduction of controlled amounts of polymer-derived carbon. Precipitation polymerization of polyacrylonitrile in the aqueous suspension of a silica material was used as a deposition method. The samples of PAN/silica composites were studied by thermal analysis, performed in air and inert atmosphere, in order to determine the amount of a deposited polymer and its thermal stability. The effect of surface area of a silica support and the monomer concentration in the mother solution on the effectiveness of deposition was revealed. The PAN/silica composites were transformed into C/SiO 2 adsorbents by carbonization carried out at 623 K. Texture (low-temperature sorption of N 2), surface structure (FTIR-DRIFT) and morphology (SEM) of the carbonized samples were investigated. The adsorption tests in the elimination of methyl–ethyl ketone from gas phase were performed under dynamic conditions. The MCM-41-based composites containing highly dispersed carbon layers on the surface appeared to be the most promising adsorbents for a commercial application. Moreover, these materials exhibited a high stability in the adsorption–desorption runs repeated ten times suggesting the possibility of regeneration of the adsorbent bed without a significant loss in the adsorption effectiveness.

Synthesis of carbon/α-Al2O3 composite adsorbents for the elimination of methyl-ethyl ketone vapour

α-Al 2 O 3 has been modified by the deposition of different amounts of polyacrylonitrile (PAN) via precipitation radical polymerization in an aqueous suspension. Carbonization of the product performed in an inert atmosphere at 350 °C resulted in obtaining of a carbon layer supported on the surface of α-Al 2 O 3 . The content of carbon in the composites was determined by temperature-programmed oxidation, whereas textural properties of the synthesized samples were studied by low-temperature sorption of N 2 (BET). The carbon/α-Al 2 O 3 composites appeared to be effective adsorbents of methyl ethyl ketone vapour.

Adsorption properties of carbonized polyacrylonitrile deposited on γ-alumina and silica gel by precipitation polymerization

The precipitation polymerization method was used for the deposition of various contents of polyacrylonitrile on two oxide-type supports (γ-alumina and silica gel). The synthesized materials were characterized by thermal analysis performed in inert and oxidizing atmospheres. The mechanism of polyacrylonitrile decomposition was proposed. In order to gain effective adsorbents of volatile organic compounds the polyacrylonitrile/support composites were carbonized at elevated temperatures. The texture and morphology of the calcined materials were examined by low-temperature sorption of N 2 and scanning electron microscopy, respectively. An influence of thermal treatment conditions and carbonaceous species loading on adsorption capacity of methyl-ethyl ketone vapour was also determined. Attenuated total reflection Fourier transform infrared spectroscopy measurements revealed that the ladder-type polyacrylonitrile species formed above 250 °C and stable up to about 350–400 °C are the most effective sites for methyl-ethyl ketone sorption. The carbonaceous species dispersion was found to be an additional factor influencing the adsorption capacity of the carbonized polyacrylonitrile/support composites.

Determination of Linear Short Chain Aliphatic Aldehyde and Ketone Vapors in Air Using a Polystyrene-coated Quartz Crystal Nanobalance Sensor

A polystyrene coated quartz crystal nanobalance (QCN) sensor was developed for use in the determination of a number of linear short-chain aliphatic aldehyde and ketone vapors contained in air. The quartz crystal was modified by a thin-layer coating of a commercial grade general purpose polystyrene (GPPS) from Tabriz petrochemical company using a solution casting method. Determination was based on frequency shifts of the modified quartz crystal due to the adsorption of analytes at the surface of modified electrode in exposure to various concentrations of analytes. The frequency shift was found to have a linear relation to the concentration of analytes. Linear calibration curves were obtained for 7-70 mg l(-1) of analytes with correlation coefficients in the range of 0.9935-0.9989 and sensitivity factors in the range of 2.07-6.74 Hz/mg l(-1). A storage period of over three months showed no loss in the sensitivity and performance of the sensor.

Biological treatment of toluene, acetone, and methyl ethyl ketone vapors with a biofilter packed with glass packing materials

Biological treatment of toluene, acetone, and methyl ethyl ketone vapors with a biofilter packed with glass packing materials

Destruction of methyl ethyl ketone vapor by ozone on activated carbon

This study attempts to combine the technologies of adsorption of volatile organic compounds (VOCs) on activated carbon and the oxidation of the VOCs by ozone (O 3). In the adsorption/oxidation process, the effects of ozone on the adsorption characteristics of methyl ethyl ketone (MEK) vapor on activated carbon are investigated. The kinetic parameters of the reaction for MEK vapor and O 3 on activated carbon are also determined. The results show that the destructive efficiencies of MEK by 1000 ppmv O 3 on activated carbon are from 12.4% to 48.5%. From the power law kinetic model, the apparent kinetic constant, k, is obtained with a value of 0.0438 h −1. Moreover, from the analytical results of the Arrhenius equation, the activation energy, E a, is found to be 5.12 kcal/mol and the value of rate constant, A, is 189.54 h −1. From the Langmuir–Hishelwood model [Escobar, P., Beroy, Q., Iritia, P.P., Huerta, J.H., 2004. Kinetic Study of the Combustion of Methyl–Ethyl–Ketone over α-Hematite Catalyst. Chem. Eng. J. 102, 107] the values of the kinetics parameters k ′ LH and k LH were 0.035 and 0.6183, respectively. Finally, the modified Wheeler equation [Busmundrud, O., 1993. Vapour Breakthrough in Activated Carbon Beds. Carbon 31, 279; Wood, G., Moyer, E.S., 1989. A Review of the Wheeler Equations and Comparison of Its Applications to Organic Vapor Respirator Cartridges Breakthrough Data. Am. Ind. Hyg. Assoc. J. 50, 400; Yoon, Y.H., Nelson, J.J., 1984. Application of Gas Adsorption Kineties I. A Theoretical for Respirator Cartridge Service Life. Am. Ind. Hyg. Assoc. J. 45, 509] in combination with the power law kinetic model or Langmuir–Hishelwood is used to predict the breakthrough curves. The destruction of MEK can be effectively promoted as the bed height of activated carbon and the concentration of ozone increase. When the ozone concentration is increased to 7800 ppmv and the amount of activated carbon is increased to 5 g the destructive efficiency of MEK is still greater than 95% even after a prolonged operational time. From the results of this study, an adsorption process in combination with ozone oxidation shows potential for the control of VOCs and odor.

Calorimetric investigation of the interaction of carbon nanotubes with polystyrene

AbstractA simple, scalable procedure that does not require covalent modification of the filler or specialized high shear mixers is described for preparing well‐dispersed carbon nanotube composites. Excellent particle dispersions of multiple‐walled carbon nanotubes (NTs) and carbon black (CB) in polystyrene (PS) are obtained by coating the particles with a <2‐nm layer of PS adsorbed from dilute solution, prior to incorporation in the composite. Improved mechanical properties of composites containing coated particles, especially NT, are demonstrated by dynamic mechanical analysis at low frequency and low amplitude. Formation of a partially immobilized region of polymer surrounding the particles is quantified using flow microcalorimetry with ethyl acetate or methyl ethyl ketone vapor to measure the increase in solvation enthalpy in this region. This calorimetric method is applied to both composites and compacted powder mixtures of NT or CB with PS. The response of integral heat of vapor sorption as a function of particle loading in powder mixtures is similar to percolation curves reported for mechanical and electrical properties of composites. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1821–1834, 2006

Easy Ketimine Formation Assisted by Heteropolynuclear Gold−Thallium Complexes

Treatment of the heterometallic complexes [AuTl(C6X5)2(L1)] (X = Cl (1a), F (1b), L1 = ethylenediamine) with ketones at room temperature yields stable amine−imine or diimine complexes with the new ligands bound to the thallium centers. Besides their reactivity in solution, both amine complexes 1a and 1b react in the solid state with ketone vapors at room temperature in a few seconds.

Equilibrium Adsorption of Phenol-, Tire-, and Coal-Derived Activated Carbons for Organic Vapors

Adsorption isotherms for alkane, aromatic, and ketone vapors were determined for activated carbon fiber cloth, tire-derived activated carbon and coal-derived activated carbon adsorbents. Physical and chemical properties of the vapors and adsorbents were used to interpret these results that were obtained from 20 to 50°C, with a more limited data set at 125 and 175°C and relative pressures between 0 and 0.99. Fitted isotherms using the Freundlich and Dubinin–Radushkevich adsorption models had mean total relative errors <5.6 and 9.2% for the microporous and mesoporous/macroporous adsorbents, respectively, at the temperature range from 20 to 50°C. The predictive direct quantitative structure activity relationship model had mean total relative errors <9.7 and 61% for the microporous and mesoporous/macroporous adsorbents, respectively, at the temperature range from 20 to 50°C without requiring experimental input.

Transient-state behavior of a biofilter removing mixtures of vapors of MEK and MIBK from air

In the work reported here, selected aspects of the dynamic behavior of biofilters for waste air treatment have been investigated. Emphasis was placed on transient state elimination of mixtures of methyl ethyl ketone (MEK) and methyl isobutyl ketone (MIBK) vapors and on explanation of the observed phenomena. The initial startup, the response of the biofilter to step changes in the pollutant loadings, responses to pollutant pulses, restarting after starvation, and the influence of step changes in gaseous phase oxygen partial pressure are presented and discussed.