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A novel, nearly isothermal, nonselective-membrane separation process, membrane vapor extraction (MVE), efficiently recovers butanol from a dilute aqueous solution, for example, from a fermentation broth (Liu et al., 2015). In MVE, feed and solvent liquids are not in contact; they are separated by vapor. Therefore, compared to conventional extraction, MVE avoids formation of difficult-to-separate emulsions. In MVE, a semi-volatile aqueous solute (e.g., butanol) vaporizes at the upstream side of a membrane, diffuses as a vapor through the membrane pores, and subsequently condenses and dissolves into a high-boiling nonpolar solvent, favorable to the solute but not to water. Design analysis of a 1.5-m long, 30-m2membrane-area countercurrent MVE unit for processing 2-wt% aqueous butanol by dodecane solvent at 40 °C indicates over 90% recovery of the feed butanol with essentially no water loss and with very low energy requirement (Liu et al., 2015). The separation factor is over 1500. However, the published design study gives no experimental evidence for the calculated MVE separation. Here, we present experimental data to validate the MVE process. We use an omniphobic (i.e., hydrophobic and oleophobic), 0.2-µm pore-diameter Versapor®200 R membrane (Pall Corporation, Exton, PA) housed in a 6-cm wide by 10-cm long plate-and-frame channeled flow cell with 0.8-cm gap thickness. Membrane transfer area is 28 cm2. The membrane flow cell is designed for minimal axial concentration change and is operated in the transient mode between two recirculating flow loops. 2-wt% aqueous butanol is extracted into dodecane or mesitylene at 25 or 40 °C. Also, 1.5-wt% furfural is extracted into dodecane at 40 °C. Since vapor transport across the membrane contributes minimal resistance, MVE performance is governed by mass transfer through feed and solvent boundary layers. Mass-transfer coefficients are determined from the Graetz-Lévêque analysis of laminar thin-slit flow

A novel, nearly isothermal, nonselective-membrane separation process, membrane vapor extraction (MVE), efficiently recovers butanol from a dilute aqueous solution, for example, from a fermentation broth (Liu et al., 2015). In MVE, feed and solvent liquids are not in contact; they are separated by vapor. Therefore, compared to conventional extraction, MVE avoids formation of difficult-to-separate emulsions. In MVE, a semi-volatile aqueous solute (e.g., butanol) vaporizes at the upstream side of a membrane, diffuses as a vapor through the membrane pores, and subsequently condenses and dissolves into a high-boiling nonpolar solvent, favorable to the solute but not to water. Design analysis of a 1.5-m long, 30-m2membrane-area countercurrent MVE unit for processing 2-wt% aqueous butanol by dodecane solvent at 40 °C indicates over 90% recovery of the feed butanol with essentially no water loss and with very low energy requirement (Liu et al., 2015). The separation factor is over 1500. However, the published design study gives no experimental evidence for the calculated MVE separation. Here, we present experimental data to validate the MVE process. We use an omniphobic (i.e., hydrophobic and oleophobic), 0.2-µm pore-diameter Versapor®200 R membrane (Pall Corporation, Exton, PA) housed in a 6-cm wide by 10-cm long plate-and-frame channeled flow cell with 0.8-cm gap thickness. Membrane transfer area is 28 cm2. The membrane flow cell is designed for minimal axial concentration change and is operated in the transient mode between two recirculating flow loops. 2-wt% aqueous butanol is extracted into dodecane or mesitylene at 25 or 40 °C. Also, 1.5-wt% furfural is extracted into dodecane at 40 °C. Since vapor transport across the membrane contributes minimal resistance, MVE performance is governed by mass transfer through feed and solvent boundary layers. Mass-transfer coefficients are determined from the Graetz-Lévêque analysis of laminar thin-slit flow

Our nitration results consistently demonstrate difficulties with the conventional nitronium ion scheme for mixed acid nitration. Ion molecule studies showed that the Wheland intermediate to aromatic nitration is not formed from the reaction NO(+2)+ArH, but rather from NO2+ArH+, a result consistent with electron transfer in aromatic nitration. In accord with this observation, we have found that the naphthalene radical cation, prepared independently and isolated as the crystalline salt and dissolved in nitromethane, reacts with NO2 in that medium to give nitronaphthalene with an alpha/beta ratio of about 50. In sulfuric acid media, we have measured directly the rates of nitronium ion formation and its rection with water over a range of acidities using 14N nmr spectroscopy. We also studied reactive aromatic hydrocarbons including mesitylene and p-xylene in fresh, NOx-free acid solution, but in the absence of NOx scavengers such as urea. In electrochemical studies in nitric acid, we have demonstrated the first electrochemical synthesis of TNT. The process takes place at room temperature in NO2/HNO3 media.

The efficiency of electronic energy transfer from the liquids benzene, toluene, p-xylene and mesitylene to p-terphenyl were determined both for UV excitation in the first absorption band and for Cs-137 gamma excitation. In addition, the efficiency with which oxygen quenches the transport process was determined for both modes of excitation. Both energy transfer and oxygen quenching constants are larger than would be pre dicted on the basis of a diffusion limited rate. Dilution of the aromatic liquids with hexane reduced the rate of energy transfer. Mechanisms of energy transfer utilizing the states of the bulk solvent are briefly reviewed. Relative scintillation efficiencies were determined for solutions of p-terphenyl in benzene, toluene, p xylene and mesitylene. The constructio- the fluorimeter is described and the emission spec trum of pure liquid benzene presented.

© 2014 Elsevier B.V. All rights reserved. Enthalpies of solution at infinite dilution of 48 organic solutes in mesitylene and 81 organic solutes in p-xylene were measured using isothermal solution calorimeter. Enthalpies of solvation for 92 organic vapors and gaseous solutes in mesitylene and for 130 gaseous compounds in p-xylene were determined from the experimental and literature data. Abraham model correlations are determined from the experimental enthalpy of solvation data. The derived correlations describe the experimental gas-to-mesitylene and gas-to-p-xylene solvation enthalpies to within average standard deviations of 1.87 kJ mol-1 and 2.08 kJ mol-1, respectively. Enthalpies of X-H⋯π (X-O, N, and C) hydrogen bond formation of proton donor solutes (alcohols, amines, chlorinated hydrocarbons etc.) with mesitylene and p-xylene were calculated based on the Abraham solvation equation. Obtained values are in good agreement with the results determined using conventional methods.

© 2014 Elsevier B.V. All rights reserved. Enthalpies of solution at infinite dilution of 48 organic solutes in mesitylene and 81 organic solutes in p-xylene were measured using isothermal solution calorimeter. Enthalpies of solvation for 92 organic vapors and gaseous solutes in mesitylene and for 130 gaseous compounds in p-xylene were determined from the experimental and literature data. Abraham model correlations are determined from the experimental enthalpy of solvation data. The derived correlations describe the experimental gas-to-mesitylene and gas-to-p-xylene solvation enthalpies to within average standard deviations of 1.87 kJ mol-1 and 2.08 kJ mol-1, respectively. Enthalpies of X-H⋯π (X-O, N, and C) hydrogen bond formation of proton donor solutes (alcohols, amines, chlorinated hydrocarbons etc.) with mesitylene and p-xylene were calculated based on the Abraham solvation equation. Obtained values are in good agreement with the results determined using conventional methods.