New Insights on the Effects of Water on Polymer Inclusion Membranes Containing Aliquat 336 Derivatives as Carriers

Abstract

Surface characterization of polymer inclusion membranes (PIMs) using the polymers cellulose triacetate and polyvinyl chloride, containing different ionic liquids (ILs) as carriers, has been performed. Three different ILs have been tested: commercial trioctyl methylammonium chloride (Aliquat 336–AlqCl−) and two derivatives bearing the counter anion NO3− or SCN− (AlqNO3 and AlqSCN, respectively). Surface analysis was performed by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) for both dry membranes and PIMs immersed for 4 days in ultrapure water to investigate the effect of the interaction of water with the membrane’s morphology and composition. XPS analysis of the PIMs revealed that immersion in ultrapure water causes a decrease in the atomic concentration percentage (A.C.%) of the specific IL atoms (Cl, S, and N) when compared with dry samples. Moreover, SEM images of the PIMs containing the IL AlqNO3 showed an alteration in the morphology of the membrane due to water contact at surface level, whereas no changes were observed at a bulk level. These changes in the surface composition of the water equilibrated PIMs may be associated with the solubilization of the IL in the water solution, which, therefore, may affect the reactivity of the membrane’s surface. To better understand this effect, PIMs containing both AlqCl and AlqNO3 as carriers were used for arsenic (V) transport. It was found that AlqCl was the most effective IL and that the effectivity of the PIM on As(V) removal was not affected after five cycles of the membrane’s reuse.

MID-FTIR-PLS Chemometric Analysis of Cr(VI) from Aqueous Solutions Using a Polymer Inclusion Membrane-Based Sensor

“…The broad band in the FTIR spectra with the maximum located near 3500 cm −1 can be attributed both to hydroxyl stretching in CTA [ 47 ] and to stretching vibrations of adsorbed water in Aliquat 336 [ 22 , 28 , 48 , 49 ]. Fontàs et al have found that modifications in the surface composition of water-equilibrated Aliquat 336-PIMs may be associated with the solubilization of the extractant in the water solution, which, therefore, may affect the reactivity of the membrane’s surface, but not the bulk properties of the membrane itself [ 50 ]. Such Aliquat 336 solubilized molecules may form micelles at the PIM [ 34 ], containing hydrated nonpolar cavities, such that the Me 3 N + headgroup in Aliquat 336 and the HCrO 4 − anion likely form solvent-separated ion pairs at the micelle surface [ 51 ].…”

Modification of the Physical Properties of a Nafion Film Due to Inclusion of n-Dodecyltriethylammonium Cation: Time Effect

“…Figure 2e presents the evolution of the N 1s contribution over the exchange time, where a peak assigned to the protonated nitrogen of DTA + is observed at 402.5 eV (N A ). Another peak attributed to the hydration of matrix impurities at around 400.0 eV (N B ) is also detected, and its intensity increases with the immersion time [38]. The atomic concentration percentages (A.C.%) of the different elements detected on the surface of the Nafion and Nafion-DTA + (t) films were obtained by analyzing the corresponding core-level spectrum curves shown in Figure 2, and are presented in Table 1.…”

Physicochemical Characterization of a Cellulosic Film Modified with Two Room-Temperature Ionic Liquids

“…. ) are commonly used in such applications, but trioctylmethylammonium chloride (or AliquatCl) and its derivatives (AliquatNO 3 or AliquatSCN), n-dodecyltriethylammonium chloride (or DTACl) and many others ILs are also usually considered [13][14][15]. In fact, a significant aspect of ILs is the possibility of tailoring their physicochemical properties via the selection of the cation/anion, which enables researchers to obtain ILs with the most adequate characteristics for a specific application.…”