Preconcentration and separation of Cr(III) and Cr(VI) using sawdust as a sorbent |
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Authors: | Email author" target="_blank">Saima?Q?MemonEmail author M?I?Bhanger M?Y?Khuhawar |
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Institution: | (1) Center of Excellence in Analytical Chemistry, University of Sindh, Jamshoro, Pakistan;(2) M. A. Kazi Institute of Chemistry, University of Sindh, Jamshoro, Pakistan |
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Abstract: | A simple, inexpensive method based on solid-phase extraction (SPE) on sawdust from Cedrus deodera has been developed for speciation of Cr(III) and Cr(VI) in environmental water samples. Because different exchange capacities
were observed for the two forms of chromium at different pH—Cr(III) was selectively retained at pH 3 to 4 whereas Cr(VI) was
retained at pH 1—complete separation of the two forms of chromium is possible. Retained species were eluted with 2.5 mL 0.1 mol L−1 HCl and 0.1 mol L−1 NaOH. Detection limits of 0.05 and 0.04 μg mL−1 were achieved for Cr(III) and Cr(VI), respectively, with enrichment factors of 100 and 80. Recovery was quantitative using
250 mL sample volume for Cr(III) and 200 mL for Cr(VI). Different kinetic and thermodynamic properties that affect sorption
of the chromium species on the sawdust were also determined. Metal ion concentration was measured as the Cr(VI)–diphenylcarbazide
complex by UV–visible spectroscopy. The method was successfully applied for speciation of chromium in environmental and industrial
water samples. |
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Keywords: | Preconcentration Separation Chromium Sawdust Sorption thermodynamics |
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