Showing papers on "Acetone published in 2018"

Catalysis for the synthesis of methacrylic acid and methyl methacrylate

Abstract: Methyl methacrylate (MMA) is a specialty monomer for poly methyl methacrylate (PMMA) and the increasing demand for this monomer has motivated industry to develop clean technologies based on renewable resources. The dominant commercial process reacts acetone and hydrogen cyanide to MMA (ACH route) but the intermediates (hydrogen cyanide, and acetone cyanohydrin) are toxic and represent an environmental hazard. Esterification of methacrylic acid (MAA) to MMA is a compelling alternative together with ethylene, propylene, and isobutene/t-butanol as feedstocks. Partially oxidizing isobutane or 2-methyl-1,3-propanediol (2MPDO) over heteropolycompounds to MAA in a single-step is nascent technology to replace current processes. The focus of this review is on catalysts and their role in the development of processes herein described. Indeed, in some cases remarkable catalysts were studied that enabled considerable steps forward in both the advancement of catalysis science and establishing the basis for new technologies. An emblematic example is represented by Keggin-type heteropolycompounds with cesium and vanadium, which are promising catalysts to convert isobutane and 2MPDO to MAA. Renewable sources for the MMA or MAA route include acetone, isobutanol, ethanol, lactic, itaconic, and citric acids. End-of-life PMMA is expected to grow as a future source of MMA.

Iron and carbon codoped WO3 with hierarchical walnut-like microstructure for highly sensitive and selective acetone sensor

Abstract: Current metal-oxide-based sensing materials are confronted with several challenges, especially in sensitivity, selectivity and stability, for their application in the breath acetone analysis. Herein, hierarchical walnut-like Fe-C-codoped WO3 microspheres were synthesized and characterized by X-ray diffraction (XRD), Raman spectra, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The amount of Fe doping was optimized based on detecting the acetone responses dependent on the operating temperature. The sensor based on the optimal Fe-C-codoped WO3 (FW3) exhibited high response to acetone and very low responses to NH3, CO, toluene, methanol, ethanol and NO. The results indicate that the optimized material possesses high sensitivity and good selectivity toward acetone vapor. Besides, the FW3 sensor presented superior anti-interferential ability to various mixed-gas systems. More importantly, the responses of the sensor exhibited no obvious fluctuation over 12 weeks, implying good long-term stability of the synthesized material. We suggest that the phase, morphology and the increased number of oxygen vacancies induced by Fe doping are the underlying reason for the improved gas sensing performance of the Fe-C-codoped WO3 microspheres.

Modified TCA/acetone precipitation of plant proteins for proteomic analysis

Abstract: Protein extracts obtained from cells or tissues often require removal of interfering substances for the preparation of high-quality protein samples in proteomic analysis. A number of protein extraction methods have been applied to various biological samples. TCA/acetone precipitation and phenol extraction, a common method of protein extraction, is thought to minimize protein degradation and activity of proteases as well as reduce contaminants like salts and polyphenols. However, the TCA/acetone precipitation method relies on the complete pulverization and repeated rinsing of tissue powder to remove the interfering substances, which is laborious and time-consuming. In addition, by prolonged incubation in TCA/acetone, the precipitated proteins are more difficult to re-dissolve. We have described a modified method of TCA/acetone precipitation of plant proteins for proteomic analysis. Proteins of cells or tissues were extracted using SDS-containing buffer, precipitated with equal volume of 20% TCA/acetone, and washed with acetone. Compared to classical TCA/acetone precipitation and simple acetone precipitation, this protocol generates comparable yields, spot numbers, and proteome profiling, but takes less time (ca. 45 min), thus avoiding excess protein modification and degradation after extended-period incubation in TCA/acetone or acetone. The modified TCA/acetone precipitation method is simple, fast, and suitable for proteomic analysis of various plant tissues in proteomic analysis.

Facile preparation of hierarchical Sb-doped In2O3 microstructures for acetone detection

Abstract: In this work, the peony-like hierarchical Sb-doped In2O3 flowers with different Sb contents have been successfully fabricated via the oxidization conversion of hydrothermally synthesized In2S3 precursors. The results of the sensing properties indicate that the as-fabricated sensors based on 2 mol% Sb-doped In2O3 hierarchical microstructures exhibit high response (64.3 for acetone with 50 ppm), fast response/recovery time (8/27 s), and long term stability characteristics towards acetone gas. Furthermore, selective detection of acetone can be readily achieved with sensors attached with 2 mol% Sb-doped In2O3 even with other common chemicals such as ethanol, methanol, benzene and ammonia around, which provide insights and strategies for developing novel acetone gas sensors used to monitor air-quality and environmental.

Self-template derived ZnFe2O4 double-shell microspheres for chemresistive gas sensing

Abstract: Porous ZnFe2O4 double-shell, york-shell, and solid microspheres are synthesized using a combination of hydrothermal method and thermal treatment (carried out at appropriate temperature determined via gravimetry). The specific surface area is varied by adopting different heating rates during the thermal treatment; double-walled structure is formed at higher heating rates. Gas sensors based on ZnFe2O4 double-shell microspheres showed a promising response (when compared to york-shell and solid microspheres), when tested with ∼20 ppm acetone (Rair/Rgas = 13.6). There is little or no response to interferential gases, including ethanol, methanol, xylene, toluene, benzene, carbon monoxide, hydrogen sulfide and nitrogen dioxide. The gas sensor showed an almost linear response to acetone concentration and a low detection limit for acetone of 0.13 ppm (making it compliant with analytic requirements for acetone-threat or diabetes-breathalyzer tests). The observed gas sensing performance (includes response time ∼6–10 s at 206 °C operating temperature and good cyclability) suggests that the ZnFe2O4 double-shell microspheres presented here are prospective sensing materials for acetone detection.

Acetone Sensing Properties and Mechanism of SnO2 Thick-Films.

Abstract: In the present work, we investigated the acetone sensing characteristics and mechanism of SnO2 thick-films through experiments and DFT calculations. SnO2 thick film annealed at 600 °C could sensitively detect acetone vapors. At the optimum operating temperature of 180 °C, the responses of the SnO2 sensor were 3.33, 3.94, 5.04, and 7.27 for 1, 3, 5, and 10 ppm acetone, respectively. The DFT calculation results show that the acetone molecule can be adsorbed on the five-fold-coordinated Sn and oxygen vacancy (VO) sites with O-down, with electrons transferring from acetone to the SnO2 (110) surface. The acetone molecule acts as a donor in these modes, which can explain why the resistance of SnO2 or n-type metal oxides decreased after the acetone molecules were introduced into the system. Molecular dynamics calculations show that acetone does not convert to other products during the simulation.

Acid-Functionalized Mesoporous Polymer-Catalyzed Acetalization of Glycerol to Solketal, a Potential Fuel Additive under Solvent-Free Conditions

Abstract: A mesoporous phenolsulfonic acid–formaldehyde polymeric acid catalyst was synthesized simply by condensation polymerization of p-phenolsulfonic acid and an aqueous solution of formaldehyde. The acid-functionalized polymer was used as a heterogeneous catalyst for glycerol acetalization with acetone for synthesis of solketal without the requirement of water removal from the reaction mixture. Solketal is extensively used as an additive for the formulation of petrol, diesel, and biodiesel. The effect of reaction parameters, such as the reaction temperature, time, catalyst loading, and glycerol/acetone molar ratio, on the glycerol conversion was exhaustively investigated in detail. Glycerol conversion of 97% and product selectivity of 100% were attained under the optimized reaction conditions: time of 4 h, temperature of 60 °C, catalyst loading of 8 wt %, and glycerol/acetone ratio of 5:1. Recycling of the used catalyst revealed good repeatability without any reactivation until the fourth cycle with a minimal ...

Activated carbons modified by magnesium oxide as highly efficient sorbents for acetone

Abstract: Porous activated carbon modified with MgO was synthesized by an evaporation-induced self-assembly (EISA) method for its application to acetone capture. The textural and chemical characteristics of five modified activated carbon composites (AC–MgO) were characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy and nitrogen adsorption isotherm measurements. The adsorption behaviors of samples for acetone were investigated and correlated to their physical and chemical properties. Density functional theory was also employed to calculate the charge transfer, the equilibrium distance, and the adsorption energy of acetone adsorbed on a carbon surface functionalized with crystalline MgO. An AC–MgO-10% sample with balanced surface area, microporosity and MgO content exhibited the highest acetone adsorption capacity (432.7 mg g−1). The results indicate that an appropriate MgO content on AC can effectively improve the adsorption capacity of acetone ascribed to strong chemisorption between MgO nanoparticles and acetone molecules.

Nitrogen-Containing Functional Groups-Facilitated Acetone Adsorption by ZIF-8-Derived Porous Carbon.

Abstract: Nitrogen-doped porous carbon (ZC) is prepared by modification with ammonia for increasing the specific surface area and surface polarity after carbonization of zeolite imidazole framework-8 (ZIF-8). The structure and properties of these ZCs were characterized by Transmission electron microscopy, X-ray diffraction, N₂ sorption, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. Through static adsorption tests of these carbons, the sample obtained at 600 °C was selected as an excellent adsorbent, which exhibited an excellent acetone capacity of 417.2 mg g-1 (25 °C) with a very large surface area and high-level nitrogen doping (13.55%). The microporosity, surface area and N-containing groups of the materials, pyrrolic-N, pyridinic-N, and oxidized-N groups in particular, were found to be the determining factors for acetone adsorption by means of molecular simulation with density functional theory. These findings indicate that N-doped microporous carbon materials are potential promising adsorbents for acetone.

Ethyl cellulose, cellulose acetate and carboxymethyl cellulose microstructures prepared using electrohydrodynamics and green solvents

Abstract: Cellulose derivatives are an attractive sustainable material used frequently in biomaterials, however their solubility in safe, green solvents is not widely exploited. In this work three cellulose derivatives; ethyl cellulose, cellulose acetate and carboxymethyl cellulose were subjected to electrohydrodynamic processing. All were processed with safe, environmentally friendly solvents; ethanol, acetone and water. Ethyl cellulose was electrospun and an interesting transitional region was identified. The morphological changes from particles with tails to thick fibres were charted from 17 to 25 wt% solutions. The concentration and solvent composition of cellulose acetate (CA) solutions were then changed; increasing the concentration also increased fibre size. At 10 wt% CA, with acetone only, fibres with heavy beading were produced. In an attempt to incorporate water in the binary solvent system to reduce the acetone content, 80:20 acetone/water solvent system was used. It was noted that for the same concentration of CA (10 wt%), the beading was reduced. Finally, carboxymethyl cellulose was electrospun with poly(ethylene oxide), with the molecular weight and polymer compositions changed and the morphology observed.

CeO2-based mixed potential type acetone sensor using La1-xSrxCoO3 sensing electrode

Abstract: In this article, CeO2-based mixed potential type gas sensor attached with sensing electrodes (SEs) consisting of perovskite-type La1-xSrxCoO3 (x = 0.1, 0.2, 0.3 and 0.5) composite oxides has been developed for acetone detection. The effect of different Sr2+ doping content in La1-xSrxCoO3 oxide material and calcination temperature on acetone sensing characteristics was investigated. It was seen that the sensor using La0.8Sr0.2CoO3 calcined at 1000 °C as SE gave the largest sensing signal to acetone in the concentration range of 1–50 ppm at 600 °C among these sensors. The response value (ΔV) of the sensor was sectionally linearly changed with the logarithm of acetone concentration within the ranges of 1–5 ppm and 5–50 ppm, and the sensitivities were −26 and −49 mV/decade, respectively. In addition, it is noteworthy that the response of the sensor to 1 ppm acetone was approximately −8.7 mV. The sensor also exhibited consistent response and recovery characteristics in five cycles, indicating the sensing device had good reproducibility. Besides, the sensor exhibited the highest response to 10 and 50 ppm acetone and less effective response to other tested gases, it indicates that the sensor has good selectivity. Furthermore, the long-term stability for the sensor to 20 ppm acetone was good because that only a slight attenuation in the sensing response was observed during 30 days. The sensing characteristics of the sensor attached with La0.8Sr0.2CoO3-SE sintered at 1000 °C to acetone were explained in terms of electrocatalytic activity changes induced by effects of doped Sr divalent cation.

Highly sensitive acetone sensors based on flame-spray-made La2O3-doped SnO2 nanoparticulate thick films

Abstract: In the present work, flame-spray-made La2O3-doped SnO2 nanoparticles with 0.1−2 wt% La contents were systematically studied for acetone detection. The particle and sensing film properties were characterized by X-ray diffraction, nitrogen adsorption, electron microscopy, energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. The sensing films were tested towards 0.1–400 ppm acetone at operating temperatures ranging from 150 to 400 °C in dry air. Gas-sensing results demonstrated that the SnO2 sensing film with the optimal La content of 0.5 wt% exhibited a very high response of 3626 toward 400 ppm acetone with a short response time of 2.8 s at the optimal operating temperature of 350 °C. Moreover, the sensors displayed high acetone selectivity against SO2, H2S, NO2, C6H6, C7H8, C8H10 and CH2O. Therefore, the La2O3-doped SnO2 sensors are promising for sensitive and selective detections of acetone at low concentrations.

Zinc Oxide Coated Tin Oxide Nanofibers for Improved Selective Acetone Sensing.

Abstract: Three-dimensional hierarchical SnO2/ZnO hetero-nanofibers were fabricated by the electrospinning method followed with a low-temperature water bath treatment. These hierarchical hollow SnO2 nanofibers were assembled by the SnO2 nanoparticles through the electrospinning process and then the ZnO nanorods were grown vertically on the surface of SnO2 nanoparticles, forming the 3D nanostructure. The synthesized hollow SnO2/ZnO heterojunctions nanofibers were further employed to be a gas-sensing material for detection of volatile organic compound (VOC) species such as acetone vapor, which is proposed as a gas biomarker for diabetes. It shows that the heterojunction nanofibers-based sensor exhibited excellent sensing properties to acetone vapor. The sensor shows a good selectivity to acetone in the interfering gases of ethanol, ammonia, formaldehyde, toluene, and methanol. The enhanced sensing performance may be due to the fact that n-n 3D heterojunctions, existing at the interface between ZnO nanorods and SnO2 particles in the SnO2/ZnO nanocomposites, could prompt significant changes in potential barrier height when exposed to acetone vapor, and gas-sensing mechanisms were analyzed and explained by Schottky barrier changes in SnO2/ZnO 3D hetero-nanofibers.

Catalytic conversion of organosolv lignins to phenolic monomers in different organic solvents and effect of operating conditions on yield with methyl isobutyl ketone

Abstract: Catalytic depolymerization of organosolv lignin to phenolic monomers with zeolites was investigated under various operating conditions. H-USY (Si/Al molar ratio = 5) outperformed H-USY with Si/Al ratios of 50 and 250, H-BEA, H-ZSM5, and fumed SiO2 to produce the highest phenolic monomer yield from a commercial organosolv lignin in methanol at 300 °C for 1 h. It was then further investigated in the presence of acetone, ethyl acetate, methanol, and methyl isobutyl ketone (MIBK) on the depolymerization of organosolv bagasse lignin (BGL). The total highest phenolic monomer yield of 10.6 wt % was achieved with MIBK at 350 °C for 1 h with a catalyst loading of 10 wt %. A final total phenolic monomer yield of 19.4 wt % was obtained with an initial H2 pressure of 2 MPa under similar processing conditions. The main phenolic monomers obtained are guaiacol (7.9 wt %), 4-ethylphenol (6.0 wt %), and phenol (3.4 wt %). The solvent properties were used to account for the differences in phenolic monomer yields obtained w...

Low Temperature Catalytic Oxidation of Binary Mixture of Toluene and Acetone in the Presence of Ozone

Abstract: This work reports on gas phase catalytic ozonation of a binary mixture of toluene and acetone and compares it with catalytic ozonation of single component acetone and toluene. Catalytic ozonation was conducted at 25–90 °C on MnOx/γ-Al2O3 catalyst. XANES and EXAFS were used to identify formal oxidation state of Mn and local structure of manganese oxide in the catalyst. Absorption energy of Mn K-edge of the catalyst was determined to be 6553.86 eV indicating that the majority of manganese in the catalyst was in 3+ oxidation state. Catalytic ozonation in the mixture was favourable for removal of toluene, and repressive for removal of acetone. This was due to (a) lower apparent activation energy of catalytic ozonation of toluene (Ea, Toluene = 31 kJ mol−1 < Ea, Acetone = 40 kJ mol−1) that led to higher reactivity of toluene with active oxygen species, and (b) inhibitory effect of accumulated carbonaceous byproducts on the acetone removal. Increase of reaction temperature enhanced conversion of both compounds, decreased the gap between toluene and acetone conversions, and improved COx yield. Overall degradation pathway of toluene and acetone in the mixture was determined by identifying the reaction intermediates and carbonaceous deposits on the catalyst. The observed mixture effects helped to understand potentials and limitations of catalytic ozonation in treating mixture of VOCs, which will aid in developing commercial air treatment systems.

MEMS-Based Acetone Vapor Sensor for Non-Invasive Screening of Diabetes

Abstract: Acetone vapor sensing is important for environmental monitoring and non-invasive screening of diabetes mellitus (DM). Inhaling higher than 176 parts per million (ppm) acetone concentrations affects the respiratory system, while acetone in exhaled breath correlates with blood glucose and exhaling more than 1.8 ppm indicates the person is in danger of DM. DM is currently diagnosed invasively by measuring glucose level in blood, which is painful, and therefore inconvenient. This paper reports MEMS sensor device functionalized with blend of Chitosan/Polyethylene glycol polymers for acetone vapor sensing for possible non-invasive screening of diabetes. The sensor was experimentally tested using synthetic acetone vapor, and found to give linear response for 0.05–5 ppm acetone in air, with a sensitivity of 21 mV/ppm, good repeatability, response, and reversibility. Cross-sensitivity for 2-propanol and methanol was examined, where the responses of the sensor to 1 ppm concentration in air of these two analytes were found to be 24% and 33%, respectively, less compared to its response to the same concentration of acetone.

Carbon Nanotube/Cellulose Acetate Thermoelectric Papers

Abstract: Free-standing single-walled carbon nanotube (SWCNT)/cellulose acetate composite films were fabricated by a simple bar-coating method. As a paste solvent, acetone, a low-boiling-point solvent, was u...

Modified TCA/acetone precipitation of proteins for proteomic analysis

Abstract: Protein extracts obtained from cells or tissues often need to remove interfering substances for preparing high-quality protein samples in proteomic analysis. A number of protein extraction methods have been applied to various biological samples, especially TCA/acetone precipitation and phenol extraction. TCA/acetone precipitation, as a common method, is thought to minimize protein degradation and proteases activity as well as reduce contaminants like salts and polyphenols. However, the TCA/acetone precipitation relies on the completely pulverizing and repeatedly rinse of tissue powder to remove the interfering substances, which is laborious and time-consuming. In addition, a prolonged incubation in TCA/acetone or acetone can lead to the modifications and degradation of proteins, and the precipitated proteins are more difficult to re-dissolve. We have described a modified TCA/acetone precipitation of plant proteins for proteomic analysis. Proteins of cells or tissues were extracted using SDS-containing buffer, precipitated with equal volume of 20% TCA/acetone, and washed with acetone. Compared to classical TCA/acetone precipitation, this protocol generates comparable yields, spot numbers, and proteome profiling, but takes less time (ca. 45 min), thus avoiding excess protein modification and degradation after extended-period incubation in TCA/acetone or acetone. The modified TCA/acetone precipitation method is simple, fast, and suitable for various plant tissues in proteomic analysis.