The role of SO{sub 4}{sup 2−} surface distribution in arsenic removal by iron oxy-hydroxides

Journal Article · Thu May 01 00:00:00 EDT 2014 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/J.JSSC.2014.02.026· OSTI ID:22334213

Tresintsi, S. ^[1]; Pliatsikas, N.; Vourlias, G.; Patsalas, P. ^[2]; Mitrakas, M. ^[1]

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1. Analytical Chemistry Laboratory, Department of Chemical Engineering, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece)
2. Laboratory of Applied Physics, Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece)

This study investigates the contribution of chemisorbed SO{sub 4}{sup 2−} in improving arsenic removal properties of iron oxy-hydroxides through an ion-exchange mechanism. An analytical methodology was developed for the accurate quantification of sulfate ion (SO{sub 4}{sup 2−}) distribution onto the surface and structural compartments of iron oxy-hydroxides synthesized by FeSO{sub 4} precipitation. The procedure is based on the sequential determination of SO{sub 4}{sup 2−} presence in the diffuse and Stern layers, and the structure of these materials as defined by the sulfate-rich environments during the reaction and the variation in acidity (pH 3–12). Physically sorbed SO{sub 4}{sup 2−}, extracted in distilled water, and physically/chemically adsorbed ions on the oxy-hydroxide's surface leached by a 5 mM NaOH solution, were determined using ion chromatography. Total sulfate content was gravimetrically measured by precipitation as BaSO{sub 4}. To validate the suggested method, results were verified by X-ray photoelectron and Fourier-transformed infrared spectroscopy. Results showed that low precipitation pH-values favor the incorporation of sulfate ions into the structure and the inner double layer, while under alkaline conditions ions shift to the diffuse layer. - Graphical abstract: An analytical methodology for the accurate quantification of sulfate ions (SO{sub 4}{sup 2−}) distribution onto the diffuse layer, the Stern layer and the structure of iron oxy-hydroxides used as arsenic removal agents. - Highlights: • Quantification of sulfate ions presence in FeOOH surface compartments. • Preparation pH defines the distribution of sulfates. • XPS and FTIR verify the presence of SO{sub 4}{sup 2−} in the structure, the Stern layer the diffuse layer of FeOOH. • Chemically adsorbed sulfates control the arsenic removal efficiency of iron oxyhydroxides.

• OSTI ID: 22334213
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Vol. 213; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
ADSORPTION
ARSENIC
BARIUM SULFATES
CHEMISORPTION
DISTRIBUTION
EFFICIENCY
FOURIER TRANSFORM SPECTROMETERS
FOURIER TRANSFORMATION
INFRARED SPECTRA
ION EXCHANGE CHROMATOGRAPHY
IONS
IRON
IRON SULFATES
LAYERS
PRECIPITATION
REMOVAL
SODIUM HYDROXIDES
SOLUTIONS
X RADIATION
X-RAY PHOTOELECTRON SPECTROSCOPY