Uptake of Fluoride from Aqueous Solution on Nano-Sized Hydroxyapatite: Examination of a Fluoridated Surface Layer

Sternitzke, Vanessa; Kaegi, Rälf; Audinot, Jean‐Nicolas; Lewin, Erik; Hering, Janet G.; Johnson, C. Annette

doi:10.1021/es202750t

Cited by 117 publications

(74 citation statements)

References 41 publications

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“…An alternative approach would be to use hydroxyapatite [HAp, Ca 10 (PO 4 ) 6 (OH) 2 ] as a possible fluoride adsorbent. Via ion exchange and/or dissolutionprecipitation reactions, HAp is able to remove fluoride to form stable fluorapatite [FAp, Ca 10 (PO 4 ) 6 F 2 ] [23], and can be obtained as bone char from food waste. FAp and HAp is stable in neutral pH range [6].…”

Section: Introductionmentioning

confidence: 99%

Properties of sludge generated by the treatment of fluoride-containing wastewater with dicalcium phosphate dihydrate

Tafu

Arioka

Takamatsu

et al. 2016

Euro-Mediterr J Environ Integr

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Fluoride-containing wastewater is discharged from various industrial sites, including semiconductor, plating, and metal-treatment plants. To remove the fluoride, we treated wastewater with dicalcium phosphate dihydrate (DCPD, CaHPO 4 Á2H 2 O) to form fluorapatite [Ca 10 (PO 4 ) 6 F 2 ] crystals. We investigated the fluoride removal efficiency and the properties of the resulting sludge. For comparison, we also treated wastewater using conventional aluminum coprecipitation. The DCPD used in this study was a by-product of the gelatin industry. Nanoscale precursor particles were induced on the DCPD by treatment with warm water. After treatment of fluoridecontaining wastewater in batch experiments, the amount, particle size distribution, settleability, and filterability of the resulting sludge were measured to assess the usability of DCPD. We found that the amount of chemical additives required for the DCPD method was less than that for the conventional method. Additionally, the amount of sludge produced using the DCPD method was small and the final fluoride concentration was below 5 mg L -1 . In settleability tests, the sludge produced by the DCPD method was precipitated within 10 min. In filterability tests, most DCPD sludge was separated within 5 min. The settleability and filterability of sludge from the DCPD method were better than those of the conventional method. The release of fluoride from the DCPD sludge was below the levels stipulated by Japanese soil pollution regulations. Consequently, the sludge was considered unlikely to cause soil pollution, thereby facilitating landfill management. We concluded that DCPD can be used effectively to treat fluoride-containing wastewater and that the resulting sludge is unlikely to cause environmental damage.

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Section: Introductionmentioning

confidence: 99%

Properties of sludge generated by the treatment of fluoride-containing wastewater with dicalcium phosphate dihydrate

Tafu

Arioka

Takamatsu

et al. 2016

Euro-Mediterr J Environ Integr

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“…22) However, the ground water in many areas has a very high F ¹ concentration. 22) HA has been reported to remove F ¹ by the exchange reaction of OH ¹ and F ¹ on the HA surface, 15) so the composition and shape of HA are important factors in F ¹ removal. The composition and the shape of HA, which is synthesized from calcium carbonate with phosphatecontaining solution, is changed significantly by the reaction conditions.…”

Section: Introductionmentioning

confidence: 99%

Ability of Hydroxyapatite Synthesized from Waste Oyster Shells to Remove Fluoride Ions

et al. 2015

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Calcium carbonates, the main component of seashell waste, can be converted to hydroxyapatite (HA) via phosphate solution treatment. HA can remove F ¹ from water, as recommended by the World Health Organization (WHO), and HA particles of small sizes and/or large amounts are expected to remove F ¹ more effectively. To control the size and amount of synthesized HA, oyster shells were treated in the (NH 4 ) 2 HPO 4 solution whose pH value was adjusted to 10 at 4120°C for 24 h. The HA particle size and amount increased with increasing reaction temperature. The samples' abilities to remove F ¹ were evaluated by immersing them in F ¹ -containing solutions. The sample treated at 30°C removed F ¹ the most effectively, achieving a F ¹ concentration below 1.5 mg·dm ¹3

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“…Sternitzke et al reported that the removal of F ¹ occurs via the formation of FA at the HA surface, resulting in the formation of FA layer of few nanometers in thickness on the surface of HA. 9) Considering the report on the formation of FA layer with thicknesses larger than a, c-lattice constant values of HA, 22) the mechanism of "dissolution of HA and precipitation of FA" is considered to be the dominant factor in the removal of F ¹ . According to this mechanism, mainly the dissolution rate of HA contributes to the F ¹ removal process.…”

Section: ¹3mentioning

confidence: 99%

Effects of carbonate inclusion on fluoride ion removal by hydroxyapatite: A discussion from the viewpoint of hydroxyapatite dissolution

Terasaka

Kamitakahara

Yokoi

et al. 2016

J. Ceram. Soc. Japan

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Hydroxyapatite (HA) can be used for removing F ¹ . Materials containing HA for removing F ¹ can be obtained from biological wastes, and these HA might contain carbonate ions. The dissolution behavior of HA should affect the F ¹ removal as fluorapatite (FA) formation at HA surface by the dissolution of HA and subsequent precipitation of FA results in the removal of F ¹ . In this study, we examined the relationship between the dissolution and F ¹ removal rates of carbonated HA (CHA). CHA samples with different carbonate contents were prepared by a hydrothermal process. The dissolution and F ¹ removal rates were investigated by immersing the samples in pH 5 and 7 buffer solutions in the absence and presence of F ¹ , respectively. The dissolution and F ¹ removal rates were increased with an increase of carbonate-ion content in the samples. Dissolution and F ¹ removal rates at pH 5 were larger than that at pH 7. The pseudo-second order kinetic model provides a good fit for the F ¹ removal process. An increase in the kinetic constant of dissolution decreases the kinetic constant of the F ¹ removal process for samples with high carbonate contents at pH 5.

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Uptake of Fluoride from Aqueous Solution on Nano-Sized Hydroxyapatite: Examination of a Fluoridated Surface Layer

Cited by 117 publications

References 41 publications

Properties of sludge generated by the treatment of fluoride-containing wastewater with dicalcium phosphate dihydrate

Properties of sludge generated by the treatment of fluoride-containing wastewater with dicalcium phosphate dihydrate

Ability of Hydroxyapatite Synthesized from Waste Oyster Shells to Remove Fluoride Ions

Effects of carbonate inclusion on fluoride ion removal by hydroxyapatite: A discussion from the viewpoint of hydroxyapatite dissolution

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