Adsorptive Removal of Fluoride from Water Using Nanomaterials of Ferrihydrite, Apatite, and Brucite: Batch and Column Studies

Abstract

This study investigated the adsorptive removal of fluoride from simulated water pollution using various (hydro)oxide nanomaterials, which have the potential to be used as sorbents for surface water and groundwater remediation. Tested nanomaterials include hematite, magnetite, ferrihydrite, goethite, hematite-alpha, hydroxyapatite (HAP), brucite, and four titanium dioxides (TiO 2 -A [anatase], TiO 2 -B [rutile], TiO 2 -C [rutile], and TiO 2 -D [anatase]). Among 11 (hydro)oxide nanomaterials tested in this study, ferrihydrite, HAP, and brucite showed two to five times higher removal of fluoride than other nanomaterials from synthetic fluoride solutions. Freundlich and Redlich-Peterson adsorption isotherms better described the adsorptive capacity and mechanism than the Langmuir isotherm based on higher R 2 values, indicating better fit of the regression predictions. In addition, the adsorption kinetics were well described by the intraparticle diffusion model. Column studies in a fixed bed continuous flow through system were conducted to illustrate the adsorption and desorption behavior of fluoride on ferrihydrite, HAP, or brucite. Experimental results fitted well with the Thomas model because of the R 2 values at least 0.885 or higher. By comparisons of the adsorption capacity and the rate constant, columns packed with ferrihydrite exhibited not only faster rates but also higher sorption capacity than those packed with *

Dual Role of Microbe–FexSy Interaction to Drive Perfluorooctanoic Acid Multipath Chain Reaction Decay Cycles and Secondary Minerals-Ions (Fe2+/Fe3+) Transformation Cycles

“…α-Fe 2 O 3 ·H 2 O and β-Fe 2 O 3 ·H 2 O led to K d of PFOA increased from 0.292 to 0.437, 0.447 cm 3 ·g –1 (Table ). Previous research has indicated that compared to α-Fe 2 O 3 (0.10 mg·g –1 ), ferrihydrite (Fe 2 O 3 ·nH 2 O) enhanced adsorption potential (0.99 mg·g –1 ) for fluoride . The unique characteristics of ferrihydrite, including its substantial surface area and intricate pore structure, enable it to provide a broad surface and abundant adsorption sites available for PFOA adsorption …”

“…Proposed mechanism of PFOA transport and fate , and minerals transformation , considering the microbe–Fe x S y interaction in four PFOA-ion occurrence environments.…”

“…Previous research has indicated that compared to α-Fe 2 O 3 (0.10 mg•g −1 ), ferrihydrite (Fe 2 O 3 • nH 2 O) enhanced adsorption potential (0.99 mg•g −1 ) for fluoride. 41 The unique characteristics of ferrihydrite, including its substantial surface area and intricate pore structure, enable it to provide a broad surface and abundant adsorption sites available for PFOA adsorption. 42 Furthermore, it has been reported that anions competed for adsorption sites with PFOA.…”

Simultaneous Removal of Arsenate and Fluoride Using Magnesium-Based Adsorbents

“…Wallace et al (2019) investigated F-removal using Mg(OH) 2 -based adsorbents [20]. They conducted fluorine adsorptive removal tests on 11 types of nanomaterials, including brucite (a Mg(OH) 2 -based adsorbent), and reported that brucite was an adsorbent with excellent F-removal performance comparable to that of ferrihydrite and apatite.…”

“…They concluded from batch test results that the F-adsorption behavior fit the Freundlich and Redlich-Petrson models better than the Langmuir model. Desorption tests were also performed during the column tests; however, the F-desorption efficiency (4-9%) was low, suggesting the difficulty in reusing the adsorbent [20].…”