Kinetics and equilibrium studies on Mg–Al oxide for removal of fluoride in aqueous solution and its use in recycling

Kameda, Tomohito; Oba, Jumpei; Yoshioka, Toshiaki

doi:10.1016/j.jenvman.2015.03.043

Cited by 17 publications

(3 citation statements)

References 25 publications

(19 reference statements)

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“…Figure a shows that the sorption of F – on 2:1 MgAl LDH at pH 7 was initially fast, with ∼20.5 mg F – /g sorbed within the first 60 min, followed by a slow equilibration time of up to 480 min (Figure a). This process could be fitted better by the pseudo-2nd-order rate equation − ( R 2 = 0.99) than by the pseudo-1st-order rate equation. To quantitatively evaluate the sorption capacity, the isotherm of F – sorption by 2:1 MgAl LDH was determined at pH 7 (Figure b) and was better fitted to the Langmuir model than to the Freundlich model.…”

Section: Resultsmentioning

confidence: 96%

Enhanced Fluoride Uptake by Layered Double Hydroxides under Alkaline Conditions: Solid-State NMR Evidence of the Role of Surface >MgOH Sites

Ren

Zhou

Liu

et al. 2021

Environ. Sci. Technol.

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Layered double hydroxides (LDHs) are potential low-cost filter materials for use in fluoride removal from drinking water, but molecular-scale defluoridation mechanisms are lacking. In this research, we employed 19F solid-state NMR spectroscopy to identify fluoride sorption products on 2:1 MgAl LDH and to reveal the relationship between fluoride sorption and the LDH structure. A set of six 19F NMR peaks centered at −140, −148, −156, −163, −176, and −183 ppm was resolved. Combining quantum chemical calculations based on density function theory (DFT) and 19F{27Al} transfer of populations in double resonance (TRAPDOR) analysis, we could assign the peaks at −140, −148, −156, and −163 ppm to Al–F (F coordinated to surface Al) and those at −176 and −183 ppm to Mg–F (F coordinated to surface Mg only). Interestingly, the spectroscopic data reveal that the formation of Al–F is the predominant mode of F– sorption at low pH, whereas the formation of Mg–F is predominant at high pH (or a higher Mg/Al ratio). This finding supports the fact that the F– uptake of 2:1 MgAl LDH was nearly six times that of activated alumina at pH 9. Overall, we explicitly revealed the different roles of the surface >MgOH and >AlOH sites of LDHs in defluoridation, which explained why the use of classic activated alumina for defluoridation is limited at high pH. The findings from this research may also provide new insights into material screening for potential filters for F– removal under alkaline conditions.

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Section: Resultsmentioning

confidence: 96%

Enhanced Fluoride Uptake by Layered Double Hydroxides under Alkaline Conditions: Solid-State NMR Evidence of the Role of Surface >MgOH Sites

Ren

Zhou

Liu

et al. 2021

Environ. Sci. Technol.

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“…The magnitude of Δ E indicates the type of adsorption, which can be physical or chemical. The physical adsorption process has lower ΔE values (5 -40 kJ  mol -1 ) [11], while the chemical adsorption has higher ΔE values (40 -800 kJ  mol -1 ) [12]. The activation energy of ordinary physical adsorption supports the high Faffinity of the product and the feasibility of the reaction.…”

Section: Fluoride Adsorption Abilitymentioning

confidence: 85%

Preparation of Fluoride Adsorbent From Zircon Sand Using Mechanochemical Treatment, and Its Application for Fluoride Removal

Minami¹

2021

GEOMATE

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Removal of low-concentration fluoride in natural water is an important issue all over the world. Japan is a volcanic country with many hot springs, and the removal of low-concentration fluoride from hot spring drainage is desired. In this study, we attempted to prepare a novel adsorbent with high selective removal ability of fluoride from zircon sand using mechanochemical treatment, and applied it for removing fluoride from hot spring water. Mechanochemical treatment of zircon sand was carried out using a planetary ball mill, and fluoride removal of the product was examined using fluoride aqueous solution and hot spring water. The hot spring water is collected from one of the hot spring in Japan, and a typical sulfuric acid hot spring water pH 2 including high contents of SO4 2-(12000 mg  L -1 ) and Cl -(5000 mg  L -1 ) with 11 -15 mg  L -1 of fluoride ion. Regardless of ball sizes, with increasing the mechanochemical treatment time to 10 min, the removal ability of the product for fluoride increases, and then be almost constant. With decreasing pH of the solution to 2, the adsorption amount increases, and then be almost constant. With increasing the temperature of the solution, the adsorption amount decreases, while the rate of adsorption increases and the amount increases. The adsorption isotherm at pH 2 follows much better Langmuir model than Freundlich model, and the calculated maximum adsorption amount is 0.11 mmol  g -1 . Fluoride can be adsorbed selectively from hot spring water below Japanese effluent standard for fluoride (8.0 mg  L -1 ).

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“…In the recent decade, synthesis and applications of metal oxide‐based composites have been reported to have a strong affinity toward fluoride adsorption. Fe–Al–Ce trimetallic oxide (Thathsara et al, 2018), Mg–Al–CO 3 double‐layered hydroxides (Lv et al, 2006), Mg–Al mixed oxide (Kameda et al, 2015), aluminum‐coated bauxite (Salifu et al, 2016), and many more have been developed for the removal of fluoride. The alumina and aluminum‐based composites have been widely investigated in the literature to remove excess fluoride from the drinking water (Maliyekkal et al, 2008; Nazari & Halladj, 2015).…”

Section: Introductionmentioning

confidence: 99%

Optimization of fluoride adsorption from aqueous solution over mesoporous titania‐alumina composites using Taguchi method

Mesfer

Danish

Shah

2021

Water Environment Research

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The optimization of fluoride removal from aqueous media was studied over the mesoporous titania‐alumina composites using Taguchi method‐based L25 orthogonal array experimental design. The chemical structure, surface chemistry, and morphology of as‐prepared composite adsorbents were studied utilizing various analytical methods. The findings of the characterization demonstrated that the produced composites have high textural qualities, which are conducive to enhanced fluoride adsorption. The optimum conditions for maximum percentage removal of fluoride from aqueous solution were found as adsorbent type as TA75, adsorbent dose 4 g L−1, initial concentration of fluoride 40 ppm, solution pH 3 with a treatment time of 60 min. Under the optimum conditions, 98% of fluoride adsorption was achieved. Analysis of variance revealed that the solution pH followed by the adsorbent dose was the most significant for fluoride adsorption. The Langmuir model and pseudo‐second‐order kinetic model fit the adsorption data well, and the TA75 adsorbent had a maximum Langmuir fluoride adsorption capacity of 34.48 mg g−1 at pH = 3. The thermodynamic information suggests that the adsorption was spontaneous and endothermic under the given operating conditions. The synergic combination of Ti–Al nanoparticles demonstrated a high percentage removal of fluoride under the optimized operating conditions. Practitioner Points The Taguchi method‐based design of the experimental approach was implemented in the fluoride adsorption process. Mesoporous titania‐alumina composites with 0 to 100 wt.% of alumina in titania were prepared and applied to remove fluoride from an aqueous solution. Solution pH was the most influential parameter for the fluoride adsorption process, while the synergistic combination of 75 wt.% alumina in titania showed the maximum adsorption capacity.

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Kinetics and equilibrium studies on Mg–Al oxide for removal of fluoride in aqueous solution and its use in recycling

Cited by 17 publications

References 25 publications

Enhanced Fluoride Uptake by Layered Double Hydroxides under Alkaline Conditions: Solid-State NMR Evidence of the Role of Surface >MgOH Sites

Enhanced Fluoride Uptake by Layered Double Hydroxides under Alkaline Conditions: Solid-State NMR Evidence of the Role of Surface >MgOH Sites

Preparation of Fluoride Adsorbent From Zircon Sand Using Mechanochemical Treatment, and Its Application for Fluoride Removal

Optimization of fluoride adsorption from aqueous solution over mesoporous titania‐alumina composites using Taguchi method

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