Evaluation of Structural Properties of Novel Activated Composite Membranes Containing Organophosphorus Extractants as Carriers

Abstract

This paper reports the results obtained by studying the structure of activated composite membranes (ACM) containing organophosphorus extractants as carriers. The porous structure of membrane samples containing different concentrations of di(2-ethylhexyl)phosphoric acid (DEHPA) and di(2-ethylhexyl)dithiophosphoric acid (DTPA) from 0 to 7 × 10 -3 mmol‚cm -2 was characterized by gas adsorption method (BET). The results obtained by the BET technique indicate that both the total pore volume and the specific surface area of ACM samples decrease with the concentration of the carrier in the casting solution. The carrier in the membrane is mainly located in pores having large and medium diameters. The chemical structure of the carriers studied does not influence their distribution in the ACM. These results correlate well with those obtained by using different spectroscopic techniques to evaluate the properties of ACM samples. Thus, a quantitative correlation has been obtained between the carrier content in the membrane and its initial concentration in the modifying solution for both organophosphorus extractants studied by using the ICP technique. Dependencies of this type can serve as a sort of calibration curve to prepare ACM samples with a desired carrier content. X-ray microanalysis (EDS) was used as a nondestructive method for determination of carrier concentration in ACM. Both EDS and impedance spectroscopy (IS) methods were applied to evaluate the changes of internal membrane structure in the course of preparation of ACM samples with different carrier content.

Transport of mercury through liquid membranes containing calixarene carriers

“…Compared to the SLM, the ACM's main advantage is the higher stability imparted by a carrier agent that is included into its solid structure. ACMs have been used for separation of metal ions and some organic molecules particularly amino acids [57][58][59][60][61][62]. The first approach and potential uses of ACM for mercury transport was studied by Paez-Hernandez et al [16].…”

“…In BLMs, R d versus time yields a exponentially decreasing dependence and R a follows a monotonically increasing curve whereas the time dependence of R m does via a maximum value [12,13,[62][63][64][65]. Note, Eqs.…”

Effect of Hydration of Polyamide Membranes on the Surface Electrokinetic Parameters: Surface Characterization by X-Ray Photoelectronic Spectroscopy and Atomic Force Microscopy

“…The composite membranes studied consist of a thin layer of polyamide (≤1 µm) deposited on a polysulfone porous support (26,39). So, the chemical information obtained through XPS analysis is derived only from the near surface of the top layer, and the polysulfone layer is not probed; thus, the main chemical elements studied by XPS were C, N, and O (the polyamide characteristic elements).…”

Application of Electrochemical Impedance Spectroscopy (EIS) and X-Ray Photoelectron Spectroscopy (XPS) to the Characterization of RTILs for Electrochemical Applications

“…Supported liquids membranes (SLMs) basically consist of an organic solvent immobilised in the pores of a support membrane [34]. SLMs has important transport advantages due to the high liquids diffusion rates and selectivity, but stability problems caused by the possible loss of the organic liquid from the porous support (or the formation of emulsions in the pores) have reduce their application in industrial separation processes [35][36].…”