Acetone

About: Acetone is a research topic. Over the lifetime, 9458 publications have been published within this topic receiving 120867 citations. The topic is also known as: propanone & dimethylketone.

Plasma-catalytic removal of a low concentration of acetone in humid conditions

Abstract: A coaxial dielectric barrier discharge (DBD) plasma reactor has been developed for plasma-catalytic removal of low concentration acetone over MOx/γ-Al2O3 (M=Mn, Co, or Cu) catalysts. The effect of relative humidity of air (RH) on the discharge characteristics, acetone removal efficiency, CO2 selectivity, and byproduct formation with and without catalyst has been investigated. The results show that increasing the RH leads to a decrease of the specific energy density (SED) of the DBD, while packing γ-Al2O3 supported metal oxide catalysts into the discharge gap enhances the SED of the discharge. The maximum acetone removal of 75.3% is achieved at an optimum RH of 10% using CoOx/γ-Al2O3 beyond which the removal efficiency of acetone decreases with the increase of the RH. Higher RH inhibits the formation of energetic electrons while water can be adsorbed onto the catalyst surface and block active sites on the catalyst surface. It is found that increasing the air humidity enhances both CO2 selectivity and carbon balance, but decreases the formation of ozone. However, the formation of NOx slightly increases with increasing the gas humidity. In addition, the presence of these catalysts in the discharge significantly decreases the formation of unwanted byproducts (O3 and NOx) and promotes the deep oxidation of acetone towards CO2 with an increased carbon balance.

Carbon dioxide fixation in the metabolism of propylene and propylene oxide by Xanthobacter strain Py2.

Abstract: Evidence for a requirement for CO2 in the productive metabolism of aliphatic alkenes and epoxides by the propylene-oxidizing bacterium Xanthobacter strain Py2 is presented. In the absence of CO2, whole-cell suspensions of propylene-grown cells catalyzed the isomerization of propylene oxide (epoxypropane) to acetone. In the presence of CO2, no acetone was produced. Acetone was not metabolized by suspensions of propylene-grown cells, in either the absence or presence of CO2. The degradation of propylene and propylene oxide by propylene-grown cells supported the fixation of 14CO2 into cell material, and the time course of 14C fixation correlated with the time course of propylene and propylene oxide degradation. The degradation of glucose and propionaldehyde by propylene-grown or glucose-grown cells did not support significant 14CO2 fixation. With propylene oxide as the substrate, the concentration dependence of 14CO2 fixation exhibited saturation kinetics, and at saturation, 0.9 mol of CO2 was fixed per mol of propylene oxide consumed. Cultures grown with propylene in a nitrogen-deficient medium supplemented with NaH13CO3 specifically incorporated 13C label into the C-1 (major labeled position) and C-3 (minor labeled position) carbon atoms of the endogenous storage compound poly-beta-hydroxybutyrate. No specific label incorporation was observed when cells were cultured with glucose or n-propanol as a carbon source. The depletion of CO2 from cultures grown with propylene, but not glucose or n-propanol, inhibited bacterial growth. We propose that propylene oxide metabolism in Xanthobacter strain Py2 proceeds by terminal carboxylation of an isomerization intermediate, which, in the absence of CO2, is released as acetone.

Comparison of Ethanol and Acetone Mixtures for Extraction of Condensed Tannin from Grape Skin

Abstract: Discrepancies in condensed tannin concentrations in grape skin determined by different analytical methods prompted the closer examination of aspects of the methodologies. One of these was the choice of extraction solvent. Condensed tannins were extracted from Shiraz grape skins using a range of aqueous solvent mixtures ranging from zero to 100% acetone and ethanol to examine the relative effectiveness of each solvent mixture and to determine whether different solvent mixtures extracted similar condensed tannin components. Acetone extracted more condensed tannin than ethanol. Mixtures of 50 to 70% acetone were equally effective. The most effective ethanol concentration was 50%. Epicatechin-gallate terminal subunits were not detected by HPLC following acid-catalysed cleavage in any of the extraction solvents. Extension subunit composition was similar between solvents across most mixtures. Polymers were generally shorter in the ethanol extracts than in the acetone extracts. Despite differences in tannin concentration and polymer length, the subunit composition was similar in 50% ethanol and 70% acetone. More tannin and tannins with longer polymer lengths were extracted with 70% acetone than with 50% ethanol. This suggests that all grape skin tannins are similar in composition, varying only in length. Thus, 50% ethanol and 70% acetone would give a fair indication of the grape skin tannin composition extracted into wine. However, both 50% ethanol and 70% acetone may overestimate the amount of tannin that is extracted into wine, as wine typically has a much lower solvent concentration, ranging between 10 and 15% ethanol.