Search results for "Chemical engineering"

Liquid chromatography and characterization of ether-functionalized imidazolium ionic liquids on mixed-mode reversed-phase/cation exchange stationary …

2010

Abstract A new series [CnOmmim]Cl of imidazolium cation-based ionic liquids (ILs), with an ether functional group on the alkyl side-chain, has been prepared. The possibility of analyzing the ionic liquids by high performance liquid chromatography (HPLC) was investigated on mixed-mode reversed/cation exchange stationary phase with the aqueous-acetonitrile mobile phase. Elution parameters, such as retention factor, selectivity and column efficiency, were studied as functions of mobile phase composition and pH. The ILs were characterized by elemental analysis, and infrared, UV and 1H, 13C NMR spectroscopy.

Detectors and Chromatography. Ed. by A.J.C. Nicholson. Pp viii + 198, Australian Scientific Industry Association, ISBN 0 949761 087

1987

Selective gas chromatographic detectors by M. Dressler, Journal of Chromatography Library, 36, Elsevier Science Publishers, Amsterdam, 334 pages, 198…

1987

Isobaric vapor–liquid equilibria for 1-propanol+water+copper(II) chloride at 100kPa

2005

Abstract Isobaric vapor–liquid equilibria for the ternary system 1-propanol + water + copper(II) chloride has been measured at 100 kPa using a recirculating still. The addition of copper(II) chloride to the solvent mixture produced a salting-out effect of the alcohol, but the azeotrope did not tend to be eliminated when the salt content increased. The experimental data sets were fitted with the electrolyte NRTL model and the parameters of Mock's model were estimated. This model has proved to be suitable to represent experimental data in the entire range of compositions. The effect of copper(II) chloride on the vapor–liquid equilibrium of the 1-propanol + water system has been compared with …

A New Simple Static Method for the Determination of Solubilities of Condensed Compounds in Supercritical Fluids

2002

Abstract A simple static method based on gravimetric measurements has been adopted to measure the solubility of benzenecarboxylic acid, 2-hydroxy-benzenecarboxylic acid, 4-hydroxy-benzenecarboxylic acid and 1,8-dihydroxyanthraquinone along several isotherms in the temperature range 318–357 K and the pressure interval 7–23 MPa. Solubility data have been correlated with the Zieger–Eckert approach, using the Fedor atomic and group contribution method to estimate the solubility parameter and the molar volume of the solutes. A good agreement was obtained between data reported in the literature and those determined using the proposed method which allows one to measure solubility mole fraction as …

Study of the effect of the membrane composition on ion transfer across a supported liquid membrane

2003

Abstract The rate of ion transfer across the supported liquid membrane (SLM) is studied in the rotating diffusion cell (RDC), varying the chemical composition of the SLM from net-cloth supported gel membranes to radiation-grafted polymer membranes. Steady-state current–voltage curves are measured as a function of the rotation rate, and values for the standard rate constant, k 0 , are determined for a series of tetraalkylammonium cations from the analysis of the initial slopes and the diffusion limiting currents. The analysis gives values for k 0 of the order of 10 −2 –10 −4 cm s −1 , which is in rather good agreement with the values found in the literature for this type of the system. As co…

Isovaleraldehyde degradation using UV photocatalytic and dielectric barrier discharge reactors, and their combinations

2015

International audience; The abatement of isovaleraldehyde present in air was carried out in UV photocatalytic and dielectric barrier discharge reactors (and their combinations) for concentrations up to 150 mg C m−3 and air flow rates ranging from 4 to 10 m3 h−1. A kinetic study was performed following a Langmuir–Hinshelwood model. Photocatalytic treatment of an isovaleraldehyde and isovaleric acid mixture showed a clear inhibition of isovaleric acid abatement in presence of isovaleraldehyde. Dielectric barrier discharge treatment of isovaleraldehyde showed an increase of removal efficiency with applied voltage and a decrease with air flow rate and inlet concentration. Moreover, introduction…

Comparison of the performance of non-ionic and anionic surfactants as mobile phase additives in the RPLC analysis of basic drugs

2011

Surfactants added to the mobile phases in reversed-phase liquid chromatography (RPLC) give rise to a modified stationary phase, due to the adsorption of surfactant monomers. Depending on the surfactant nature (ionic or non-ionic), the coated stationary phase can exhibit a positive net charge, or just change its polarity remaining neutral. Also, micelles in the mobile phase introduce new sites for solute interaction. This affects the chromatographic behavior, especially in the case of basic compounds. Two surfactants of different nature, the non-ionic Brij-35 and the anionic sodium dodecyl sulfate (SDS) added to water or aqueous-organic mixtures, are here compared in the separation of basic …

Alcoholic nanolime dispersion obtained by the insolubilisation-precipitation method and its application for the deacidification of ancient paper

2017

Abstract Nanolime dispersions for the deacidification of ancient paper constitute a valid alternative to the lime traditional ones. Their efficacy depends on particles size, polydispersity and agglomeration that can be controlled depending on the preparation method. In this work, nanolime preparation by insolubilisation-precipitation method is reported. Nanoparticles dispersed in a water-isopropanol mixture were obtained without any manipulation of the dispersion. The stability of the dispersion together with particle size and morphology were found to be dependent on water to isopropanol molar ratio and on the synthesis temperature. One of the dispersion was applied on a manuscript to asses…

Role of Phase Behavior and Atomization in the Supercritical Antisolvent Precipitation

2003

An experimental study on supercritical antisolvent (SAS) precipitation has been performed to gain insight into the role of phase behavior and atomization in controlling morphology and dimension of precipitates. The mixture yttrium acetate/dimethyl sulfoxide has been used as the main model system and supercritical CO 2 has been used as the antisolvent. Two SAS apparatuses (laboratory and pilot scale) with two injector arrangements and operating with various injector diameters in the range 60-500 μm have been used. The results showed that operating above the mixture critical point (MCP) of the ternary mixture yttrium acetate/dimethyl sulfoxide/ carbon dioxide, sub-micrometric particles are ge…