Chromium speciation using aqueous biphasic systems: Development and mechanistic aspects
Autor: | Roselaine C. da Cunha, Luis Henrique Mendes da Silva, Pamela R. Patrício, Maria do Carmo Hespanhol da Silva, Silvia J. R. Vargas, Yara Luiza Coelho |
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Rok vydání: | 2016 |
Předmět: |
Chromium
Green chemistry 021110 strategic defence & security studies Aqueous solution Ethylene oxide Speciation Extraction (chemistry) Inorganic chemistry 0211 other engineering and technologies chemistry.chemical_element Aqueous biphasic system Filtration and Separation 02 engineering and technology Electrolyte 021001 nanoscience & nanotechnology Fluorescence Fluorescence spectroscopy Analytical Chemistry Separation process chemistry.chemical_compound chemistry 0210 nano-technology |
Zdroj: | LOCUS Repositório Institucional da UFV Universidade Federal de Viçosa (UFV) instacron:UFV |
ISSN: | 1383-5866 |
Popis: | The two principal oxidation states of chromium diverge significantly in their biological and toxicological properties, and it is very important to distinguish between them. Develop procedures that are efficient, fast, easier and cheaper for chromium speciation is an analytical challenge. Chromium speciation was investigated using aqueous biphasic systems (ABS) formed by polyethylene oxide (PEO1500) or a triblock copolymer (L64), an electrolyte (Li 2 SO 4 , Na 2 SO 4 , MgSO 4 , C 6 H 5 Na 3 O 7 , or C 4 H 4 Na 2 O 6 ) and water, without the presence of any extractant. Cr(III) was favorably partitioned to the electrolyte-rich phase (ERP) of the ABS, whereas the Cr(VI) was preferentially concentrated in the macromolecule-rich phase (MRP) in most analyzed ABS. The fluorescence spectroscopy data revealed that the Cr(III) and Cr(VI) separation process is governed by specific interactions between the ethylene oxide segments in the macromolecules and the Cr(VI) species, which do not occur for Cr(III) species. The extraction percentage (% E ) of chromium species from the ERP to the MRP was affected by pH, tie-line length (TLL), electrolyte nature, and macromolecule hydrophobicity. For the ABS comprising of PEO1500 + Na 2 SO 4 + H 2 O, TLL = 50.89% (m/m), 25 °C and pH 2.0, the % E values for Cr(III) and Cr(VI) were 0.0100 and 99.9%, respectively. The speciation of Cr(III) and Cr(VI) that was achieved in this ABS resulted in an excellent separation factor ( S Cr(VI),Cr(III) ) of 1.00 × 10 8 . |
Databáze: | OpenAIRE |
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