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Fast, green and effective chromium bio-speciation using Sepia pharaonis endoskeleton nano-powder
Khedri, N.; Ramezani, Z. & Rahbar, N.
Abstract
The development of a fast, effective, simple and
low-cost procedure for chromium speciation is an analytical
challenge. In this work, a new and simple method for
speciation and determination of chromium species in different
matrices was developed. Sepia pharaonis
endoskeleton nano-powder was used as an adsorbent for
the dispersive micro-solid-phase extraction. Finally, the
desorbed chromium was determined using a graphite furnace
atomic absorption spectrometer. The experimental
results showed that Cr(III) could be quantitatively extracted
by the adsorbent, while Cr(VI) adsorption was negligible.
Concentrated H2SO4 and ethanol reduced Cr(VI)–
Cr(III), and total chromium content was assessed as Cr(III).
Then, the Cr(VI) concentration in the sample was calculated
as the difference. The optimum conditions were
obtained in terms of pH, adsorbent amount, contact time,
and type, concentration and volume of eluent. Under the
optimum conditions that involved the speciation of chromium
ions from 25 mL of the water samples at pH 7.0
using 0.025 g of the adsorbent with contact time of 5 min,
the method was validated in terms of linearity, precision
and accuracy. The calibration curve was linear over the
concentration range of 0.01–25.00 µg L-1 for Cr(III). The
obtained limit of detection for the proposed method was
0.003 µg L-1. The maximum adsorption capacity of the
adsorbent was found to be 995.57 mg g-1. The proposed
method was validated by the speciation of Cr(III) and
Cr(VI) in different real water and wastewater samples with
satisfactory results.
Keywords
Chromium; Speciation; Nano-powder; Cuttlefish endoskeleton; Sepia pharaonis
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