Measurement of free glycerol in biofuels

A method has been developed to determine the free glycerol content in esters derived from vegetable oils. After extraction of glycerol, its measurement in small quantities in biofuels (methyl or ethyl esters) is possible by high-pressure liquid chromatography combined with pulsed amperometric detection, HPLC-PAD. The method has proved to be simple, rapid and accurate. The limit of detection is 1 g/g.     

Synthesis and properties of aromatic polyamides with oligobenzamide pendent groups. I. Poly-5-(4-benzoylamino-1-benzoylamino)isophthalamides

A series of polyisophthalamides having pendent oligomeric benzamide groups were prepared by the Yamazaki reaction from common aromatic diamines and 5-(4-benzoylamino-1-benzoylamino)isophthalic acid. The latter was synthesized from 5-aminoisophthalic acid in a three-step synthesis by successive incorporation of benzamido groups. The new polymers were characterized by NMR, DSC, TGA, and WAXD and the properties were compared to those of corresponding unsubstituted polyisophthalamides. All of the polymers were essentially amorphous and their T_gs were about 20°C higher than the reference polymers. Initial thermal decomposition temperatures ranged from 375 to 420°C. All of the polymers were soluble in aprotic polar solvents without added salts. Properties of particular note were: the water uptake, which was particularly high, ranging from 7.5 to 18.2%, and the temporary insolubilization in concentrated sulfuric acid of films of the polymers heated for a short time to ≥ 200°C. © 1995 John Wiley & Sons, Inc.     

Ionic liquid ion sources: characterization of externally wetted emitters

The feasibility of electrostatically extracting and accelerating ions from room temperature ionic liquids in a high vacuum environment is investigated using externally wetted emitters similar to those manufactured for liquid metal ion sources, made out of tungsten wire and electrochemically treated to produce a sharp tip and to increase surface wettability. The ionic liquid EMI-BF4 is used as a prototypical example. The temperature dependence on emission current suggests that liquid flow over the metallic surface is limited by viscosity. Time-of-flight spectrometry indicates that the beam is composed of EMI+ and (EMI-BF4)EMI+ ions in the positive polarity and BF4- and (EMI-BF4)BF4- ions in the negative polarity, and that these ions are emitted with energies very close to their applied potentials. Angular distribution measurements in positive and negative polarities show that ions travel near the propagation axis, diverging by not more than 18 degrees from the centerline. Thanks to the extraordinary variety of ionic liquids it should be possible to generate a correspondingly large number of bipolar nonmetallic ion beams each with unique properties and applicability in fields as diverse as ion lithography, analytical equipment and space propulsion.     

Synthesis and characterization of halogen‐containing poly(ether ketone ketone)s

A series of novel poly(ether ketone ketone)s (PEKKs) were synthesized from diphenyl ether and isophthaloyl chloride derivatives such as 5‐halo‐ and 5‐tert‐butyl‐isophthaloyl chloride. The aromatic electrophilic substitution route to polyketones was a convenient route for the preparation of the polymers in high yields via precipitation polycondensation at a low temperature with aluminum trichloride as a catalyst. High molecular weight PEKKs were achieved with number‐average molecular weights of 15,000–100,000 g/mol for polymers that showed good solubility in organic solvents. The presence of substituents greatly modified the spectroscopic features in comparison with those of unsubstituted isophthaloyl poly(ether ketone ketone)s, particularly for the series containing halogens, for which significant variations of the chemical shifts in both ¹H and ¹³C NMR spectra were observed; these shifts could be related to the nature of the halogen. Thermal properties were also affected by the presence of pendent substituents, with clear enhancements of the glass‐transition temperatures, which could be ascribed to the nature and bulkiness of the substituents. Thermogravimetric analyses showed that the new polymers had good thermal resistance, although an important drop in thermal resistance was observed for polymers bearing large halogen atoms, such as bromine and iodine. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2601–2608, 2002     

Simultaneous determination of pentachlorophenol and carbaryl in water

Summary A rapid method for the simultaneous determination of pentachlorophenol (PCP) and Carbaryl in water is described. A 1 liter water sample is extracted with hexane after acidification with concentrated H₂SO₄. After evaporation to a small volume, the extract is analyzed by gas chromatography-mass spectrometry, operating in the selected ion monitoring mode. Estimated detection limits are 0.08 g L^–1 for PCP and 0.11 g L^–1 for Carbaryl, with recoveries of 96% for PCP and 97% for Carbaryl.