Fluoride Adsorption Onto Granular Ferric Hydroxide: Effects of Ionic Strength, PH, Surface Loading, and Major Co-Existing Anions
Fluoride adsorption onto granular ferric hydroxide (GFH) was investigated using batch methods, under various ionic strength, pH, surface loading, and major co-existing anion conditions. Adsorption of fluoride on GFH included an initial fast adsorption phase followed by a slow adsorption phase. within the pH range of 2-11, fluoride adsorption equilibrium was not affected by ionic strength, but was significantly affected by pH. Maximum adsorption was achieved in the pH range of 3-6.5. under the same pH condition, fluoride adsorption followed the Freundlich isotherm, indicating that the GFH surface was heterogeneous. X-ray photoelectron spectroscopy (XPS) and attenuated total reflection-infrared (ATR-IR) spectroscopy data showed evidence for fluoride sorption on the GFH surface via inner-sphere complexation accompanying increased hydrogen bonding and surface hydroxylation. Major anions, including phosphate, bicarbonate, sulfate, and chloride, reduced fluoride adsorption in the following order: H2PO4- > HCO3- > SO42- > Cl-.
Y. Tang et al., "Fluoride Adsorption Onto Granular Ferric Hydroxide: Effects of Ionic Strength, PH, Surface Loading, and Major Co-Existing Anions," Journal of Hazardous Materials, Elsevier, Nov 2009.
The definitive version is available at http://dx.doi.org/10.1016/j.jhazmat.2009.06.079
Civil, Architectural and Environmental Engineering
China Scholarship Council
Missouri University of Science and Technology. Environmental Research Center
University of Missouri Research Board
Keywords and Phrases
XPS; Granular Ferric Hydroxide; Ionic Strength; pH; Adsorption; Fluorides; X-ray photoelectron spectroscopy
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