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A polymeric inclusion membrane using di-(2-ethylhexyl)phosphoric acid (D2EHPA) as carrier, 2-nitrophenyl octyl ether (2NPOE) as plasticizer, and cellulose triacetate (CTA) as base polymer was employed to evaluate the facilitated transport of Cr(III) in aqueous medium. An experimental design strategy based on a Doehlert matrix was used to optimize the membrane composition, using two normalized functions as response variables (Gfeed, Gstrip). The amounts of D2EHPA, NPOE, and CTA used in the experimental design varied within the range 0.03–0.075 g; the concentration of the feed phase used was 6 mg/L Cr(III) at pH 4.0 adjusted with 0.01 mol/L AcOH/AcONa buffer solution; and 1 mol/L HCl was used as the strip phase. The optimal membrane reached a maximum recovery of (96.0 ± 0.6)% after 8 h of pertraction. The effects of pH of the feed phase and the presence of different interfering ions ( SO 4 2 - , Cl - , Na + , K + , and Ca 2 + ) were evaluated as well. Based on liquid–solid extraction experiments, the extraction and transport mechanisms for the system were proposed. [ABSTRACT FROM AUTHOR]

Efficient Ni (II) transport through a polymer inclusion membrane (PIM) was achieved. A central composite design (DCC) coupled to a Derringer's desirability function (DF) was used to optimize membrane composition using Kelex 100 (HQ) as carrier, cellulose triacetate (CTA) as polymer support, and tris(2-ethylhexyl) phosphate (TEHP) as plasticizer. The effect of components' contents in the membrane and the interactions among them on Ni (II) migration was evaluated using two normalized function as response variables (GFeed, GStrip). Using the optimal membrane composition, (96 ± 1.5) % of Ni (II) was detected in the strip solution after 48 h of pertraction. The efficiency factors of the system were determined, i.e., permeability (optimization pH of the aqueous samples and initial metal concentration), selectivity (among Zn (II), Pb (II), Cu (II), Ca (II) and Mg (II)), and stability (reuse capability). Ni (II) transport mechanism was proposed and analyzed as well. [ABSTRACT FROM AUTHOR]

The present study provides an alternative view of the applications of response surface methodology (RSM) coupled to the Derringer's desirability function (DF) to analyze and optimize system's composition to target different environmental applications related to the transport of As (V) through polymer inclusion membranes (PIMs). In this case, membranes contained cellulose triacetate (CTA), as support, trioctylmethylammonium chloride (Aliquat 336 = A336), as carrier, and tris(2-ethylhexyl) phosphate (TEHP), as plasticizer. A four-factor Doehlert design (variables: CTA weight, A336 and TEHP content, and HCl concentration) was employed. Statistical data analyses showed that A336, TEHP, CTA, and different kinds of interactions among them determined As (V) migration, depending on the measured response (PFeed, PStripping, ΔpH, or PIM thickness). For instance, an efficient system able to maximize the permeabilities, without altering the pH of feed solution, is obtained using as composition 22% CTA, 48% A336, and 30% TEHP and 0.1 mol/L HCl solution in the strip phase. If the change of pH is not relevant, 40% CTA and 60% A336 lead to a higher transport when the strip solution conditions are maintained. Furthermore, the composition 46% CTA, 35% A336, and 20% TEHP is suggested for passive sampling devices with speciation capabilities. [ABSTRACT FROM AUTHOR]