The water sorption behavior of representative pyridinium-based ionic liquid (IL), 1-hexylpyridinium hexafluorophosphate ([C6Py][PF6]), was studied over the whole range of the water activity a using a continuous gravimetric method. The analysis of the water sorption isotherm using the combination of a two-mode sorption (i.e. Henry-clustering) allowed to better understand [C6Py]PF6]-water interactions. At low and intermediate activity (a <= 0.8), the water molecules revealed a very low affinity to [C6Py][PF6] and, consequently, the water uptake was rather low. On the contrary, at high water activity (a > 0.8), the water uptake increased exponentially and the water clustering easily occurred. The constant of the Henry-clustering equation as well as the water clustering mechanism in [C6Py][PF6] were discussed and compared to those of imidazolium-based ILs: 1-hexyl-3-methylimidazolium hexafluorophosphate [C(6)C(1)im][PF6] (water-immiscible IL) and 1-butyl-3-methylimidazolium tetrafluoroborate [C(4)C(1)im][BF6] (water-miscible IL). It is shown that the sorption of water molecules by pyridinium-based ILs is controlled not only by the anion's nature, but also by the cation's nature. Moreover, the Zimm-Lundberg theory was used to determine the water mean cluster size (MCS) in [C6Py] [PF6]. [C(6)C(1)im][PF6] and [C(4)C(1)im][BF4]. The MCS results confirmed the strong capacity of water molecules to be aggregated in [C(6)PA[PF6]. In order to have a deeper insight into the water molecular state, infrared spectroscopy measurements were carried out as a function of the relative humidity value and the obtained results were correlated with the results of water sorption isotherms. It is found that at high water activity (a > 0.8), sorbed water molecules are strongly linked with ILs by hydrogen bonds and, therefore, are easily aggregated. (C) 2019 Published by Elsevier B.V.

The present study focuses on the chemical and physical characterization of the water-soluble fraction of the Commiphora Africana exudate. The chemical analysis proved that this fraction is mainly composed of carbohydrates and hydrophobic amino acids. Size exclusion chromatography (SEC) revealed the presence of three distinct polysaccharide populations that are all bonded to protein. In addition, both SEC and rheology demonstrated that the gum owns highly compact structure that suggests an AGP-like polymer. Commiphora Africana gum exhibits excellent surface activity at concentration 2 orders of magnitude lower than the reference, acacia gum and was attributed to the fact that the three populations contribute to the surface tension lowering. This remarkable property has been confirmed by preliminary experiments on model emulsions and suggests a very promising application in formulation. (C) 2017 Elsevier Ltd. All rights reserved.

The present study focuses on the chemical and physical characterization of the water-soluble fraction of the Commiphora Africana exudate. The chemical analysis proved that this fraction is mainly composed of carbohydrates and hydrophobic amino acids. Size exclusion chromatography (SEC) revealed the presence of three distinct polysaccharide populations that are all bonded to protein. In addition, both SEC and rheology demonstrated that the gum owns highly compact structure that suggests an AGP-like polymer. Commiphora Africana gum exhibits excellent surface activity at concentration 2 orders of magnitude lower than the reference, acacia gum and was attributed to the fact that the three populations contribute to the surface tension lowering. This remarkable property has been confirmed by preliminary experiments on model emulsions and suggests a very promising application in formulation.

The aim of the work is to study the impact of the cold plasma treatment on the elaboration and stability of the supported ionic liquid membranes (SILMs). The porous support was prepared from Matrimid 5218 by the water vapor induced phase inversion. The porous structure characterized by SEM showed a spongy, interconnected and relatively symmetrical structure with macropores ranging between 10 and 15 pm. A porous Matrimid membrane was treated with either hydrophobic (CF4) or hydrophilic (N-2 or O-2) plasma using a radio frequency discharge according to the optimum plasma parameters for each gas. The porous membrane was then impregnated with [C(4)C(1)im][BF4] and [C(4)C(1)irn][PF6] using the direct immersion method. An acceleration of the room temperature ionic liquid (RTIL) impregnation in the case of N-2 and O-2 plasma treatments was observed due to both the grafted polar functions on the surface and the increase of surface roughness. On the other hand, the nonpolar surface functionalization after the CF4 plasma treatment slowed and delayed the RTIL impregnation. The SILMs were composed of,-60% of the RTIL phase, and no effect of the plasma treatments on the RTIL uptake mass was found. The bubble point method was used to evaluate the SILM stability. Although the bubble point pressure was independent of the plasma treatments, the retention of the RTIL phase inside the membrane was found to be improved. (C) 2017 Elsevier B.V. All rights reserved.

Surface functionalization of polyimide films was carried out by cold plasma treatment using a radio frequency discharge and the optimum plasma conditions were evaluated by water contact angle measurements. The relationship between gas permeation behaviour and surface modification of the films was discussed.

Supported ionic liquid membranes (SILMs) were prepared by immobilizing the room temperature ionic liquids (RTILs) ([C(4)C(1)im][BF4] and [C(n)C(1)im][PF6] (n=4 and 6)) in a porous Matrimid membrane. The Matrimid membrane was prepared by water vapor induced phase inversion, and its porous structure was characterized by SEM. After immersion of the porous Matrimid membrane in RTILs, the prepared SILMs were composed of 60% of RTIL phase. From the bubble point Lest, the SILMs displayed an excellent retention of their RTIL phase, and thus showed a good stability in the face of increased pressure on one of their faces.The feasibility of the prepared SILMs for the separation of water and volatile organic compounds (VOCs) such as ethanol and cyclohexane by vapor permeation was investigated. For this purpose, a preliminary study of water and VOC vapor sorption in RTILs was necessary to determine the affinity between each solute and RTILs. Only [C(4)C(1)im][BF4] showed both the best sorption capacities and the good sorption selectivities. The vapor permeation measurements were therefore carried out only through the SILMs impregnated with [C(4)C(1)im][BF4]. The SILM permeability was found to increase in the same sorption affinity order as for [C(4)C(1)im][BF4], i.e. cyclohexane < ethanol < water (in molar unit); moreover, the best ideal selectivities of the SILM based on [C4C1-im][BF4] were related to the separation of cyclohexane with alpha(water/cyclohexane) = 371 and alpha(ethanol/cyclohexane) = 217. Moreover, the SILMs retained most of their [C(4)C(1)im][BF4] phase regardless of the vapor used, and thus showed satisfactory stability as well as durability under the permeation conditions used. (C) 2014 Elsevier B.V. All rights reserved

Supported ionic liquid membranes (SILMs) were prepared by impregnating a porous Matrimid (R) membrane with protic room-temperature ionic liquids (RTILs): 1-n-methylimidazolium dibutylphosphate ([C-1 im][DBP]), 1-n-butylimidazolium dibutylphosphate ([C(4)im][DBP]) and 1-n-butylimidazolium bis(2-ethylhexyl)phosphate (C(4)im[BEHP]). After immersion of the porous Matrimid (R) membrane in each RTIL, the prepared SILMs were composed of 53 +/- 3% of RTIL phase. The control of the full impregnation of the porous Matrimid (R) membrane by the RTILs was verified by FTIR spectroscopy. From the bubble point test, the SILMs displayed a good retention of their RTIL phase and, thus, showed a good stability against the increased pressure on one of the faces. The ionic conductivity of SILMs, used as electrolyte membranes for proton exchange membrane fuel cell (PEMFC) was measured by impedance spectroscopy. Unlike the Nafion (R) the conductivity of the SILMs still increases at high temperatures (> 80 degrees C). The [C(4)im][DBP]-impregnated SILM showed the best result in terms of conductivity (2.010(-2) S/cm at 115 degrees C). Moreover, all SILMs showed satisfactory stability since they retained a large amount of the RTIL phase in the membrane pores. (C) 2014 Elsevier Ltd. All rights reserved.