پديدآورندگان :
Yaftian Mohammad Reza yaftian@znu.ac.ir Department of Chemistry, The University of Zanjan; 45371-38791 Zanjan, Iran / School of Chemistry, The University of Melbourne, Victoria 3010, Australia; , Almeida M. I. G. S. School of Chemistry, The University of Melbourne, Victoria 3010, Australia , . Cattrall R. W School of Chemistry, The University of Melbourne, Victoria 3010, Australia , Kolev S. D. School of Chemistry, The University of Melbourne, Victoria 3010, Australia
چكيده فارسي :
Even though supported liquid membrane (SLM)-based separations are alternative to solvent extraction, they suffer from poor stability due to leaching of the organic phase into the adjacent liquid phases. Polymer inclusion membranes (PIMs), a relatively recently developed liquid membranes, are known to be more stable than SLMs because the membrane liquid phase is entangled within the polymer chains. PIMs are composed of an extractant, a base polymer, and, in some cases, a plasticiser. They are typically prepared by casting a solution of all membrane components in a volatile solvent and allowing the solvent to evaporate slowly. PIMs have been applied in extraction and transport processes of a variety of analytes, paper-based sensing, passive samplers and in on-line separation for the selective determination of ions in FIA systems.[1]The gradual depletion of vanadium containing ore reserves and the increased industrial consumption of this metal, have promoted researchs for its recycling from secondary sources, such as spent hydrodesulfurisation catalysts. Beside the economically importance of vanadium recovery, the determination of V(V), as a pollutant, is also essential. Although, spectrophotometric methods are most frequently used for the V(V) determinations, the reagents used in these methods are not generaly selective and therefore an appropriate separation step should be introduced to allow reliable determination of V(V).The first part of this communication is devoted to describe the development and application of a poly(vinylidene-fluoride-co-hexafluoropropylene) (PVDF-HFP)-based PIM containing trihexyltetradecyl-phosphonium chloride (Cyphos® IL 101) as extractant, for the selective extraction of V(V) from sulfate solutions. A PIM composition containing Cyphos® IL 101, PVDF-HFP and 2-nitrophenyloctyl ether (35:55:10 wt% ratio) was able to efficiently extract V(V) from 0.2 M sulfate solutions, at pH 2.3. It was suggested that the presence of sulfate promoted the formation of VO2SO4-, which was extracted via an anion exchange mechanism with Cyphos® IL 101. The loaded PIMs could be quantitatively back-extracted with 6 M H2SO4. The selectivity of the PIM towards V(V) was tested with a mixture of Mo(VI), Al(III), Co(II), Cu(II), Fe(III), Mn(II), and Ni(II). The interference of Mo(VI) was resolved by designing a two-step procedure.[2] The optimized PIM was stable for at least five extraction/back-extraction cycles.The study was followed by introducing a FIA system that incorporates the developed PIM in an extraction cell [3] for the on-line selective separation of V(V) which was followed by its spectrophotometric determination using xylenol orange. The developed method was applied to the determination of V(V) in various samples. Univariate sequential optimization of the various parameters controlling the FIA system, was carried out. Under optimal conditions the system was characterized by a linear concentration range of 0.5–8.0 mg/L, detection limit of 0.08 mg/L and sample throughput of 4 h−1. The RSD at the 3 mg/L level of V(V) was 2.9% (n=8). The membrane was stable, which was reflected by the standard deviation value for determinations over three consecutive days (24 determinations of 3 mg/L V(V)) of 3.6%. The developed FIA system was applied to the determination of V(V) in water and dietary supplements samples and a good agreement with ICP-OES was observed.
