Separation and spectrophotometric determination of very low levels of Cr(VI) in water samples by novel pyridine-functionalized mesoporous silica

A modified SBA-15 mesoporous silica was developed, as an adsorbent, for the removal of Cr(VI) ions from natural-water samples. The effects of experimental parameters, including pH of solution, sample and eluent flow rate, the eluent composition, the eluent volume, and the effect of coexisting ions o...

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Bibliographic Details
Published in:International journal of environmental analytical chemistry 2012-04, Vol.92 (4), p.509-521
Main Authors: Ebrahimzadeh, Homeira, Asgharinezhad, Ali A, Tavassoli, Najmeh, Sadeghi, Omid, Amini, Mostafa M, Kamarei, Fahimeh
Format: Article
Language:English
Subjects:
Adsorption
Aqueous solutions
chromium
Cr(VI)
detection limit
Ions
potassium chloride
py-SBA-15
pyridine-functionalized mesoporous silica
separation and preconcentration
Silica
sodium carbonate
wastewater
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Summary:A modified SBA-15 mesoporous silica was developed, as an adsorbent, for the removal of Cr(VI) ions from natural-water samples. The effects of experimental parameters, including pH of solution, sample and eluent flow rate, the eluent composition, the eluent volume, and the effect of coexisting ions on the separation and determination of Cr(VI), were investigated. It was shown that Cr(VI) was selectively adsorbed from aqueous solution at pH 3, but Cr(III) could be adsorbed from solution at alkaline pH range. The retained Cr(VI) was eluted with 0.5 mol L⁻¹ KCl solution in 0.1 mol L⁻¹ Na₂CO₃ subsequently. Under the optimum conditions, the modified mesoporous silica (py-SBA-15) with a high pore diameter exhibited an adsorption capacity of 136 mg g⁻¹ and a lower limit of detection than 2.3 µg L⁻¹ by using diphenylcarbazide as a chromophorous reagent for the determination of Cr(VI) ions. A preconcentration factor as high as 200 was calculated for Cr(VI). The loaded py-SBA-15 can be reactivated with recovery of more than 98.5% over at least eight cycles. The relative standard deviation (RSD) for Cr(VI) ion recovery was less than 1.8%. Validation of the outlined method was performed by analysing a certified reference material (BCR 544). The proposed method was applied to determine Cr(VI) value in natural and waste water samples successfully.
ISSN:1029-0397
0306-7319
1029-0397
DOI:10.1080/03067319.2011.603081