Removal of fluoride ions from aqueous solutions by multivalent metal compounds

Tokunaga, S.; Haron, Md. Jelas; Wasay, S. A.; Wong, Kwan-Yiu; Laosangthum, K.; Uchiumi, Akira

doi:10.1080/00207239508710973

Cited by 81 publications

(35 citation statements)

References 6 publications

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“…The effluent pH rose from the initial value of 5.0 to pH of 6.2-6.7 following adsorption for 24 h (data not shown). From the changes of FTIR spectra and pH, it was speculated that substitution of M-OH groups by As(V) ions plays a key role in the adsorption mechanisms, which is in accordance with the results obtained by Tokunaga et al (7).…”

Section: Resultssupporting

confidence: 89%

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Arsenate Adsorption on an Fe−Ce Bimetal Oxide Adsorbent: Role of Surface Properties

Zhang

Yang

Dou

et al. 2005

Environ. Sci. Technol.

511

247

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An Fe-Ce bimetal adsorbent was investigated with X-ray powder diffraction (XRD), transmission electron micrograph (TEM), Fourier transform infrared spectra (FTIR), and X-ray photoelectron spectroscopy (XPS) methods for a better understanding of the effect of surface properties on arsenate (As(V)) adsorption. In the adsorption test, the bimetal oxide adsorbent showed a significantly higher As-(V) adsorption capacity than the referenced Ce and Fe oxides (CeO 2 and Fe 3 O 4 ) prepared by the same procedure and some other arsenate adsorbents reported recently. XRD measurement of the adsorbent demonstrated that the phase of magnetite (Fe 3 O 4 ) disappears gradually with the increasing dosage of Ce 4+ ions until reaching a molar ratio of Ce 4+ to Fe 3+ and Fe 2+ of 0.08:0.2:0.1 (Fe-Ce08 refers to the adsorbent prepared at this ratio), and the phase of CeO 2 begins to appear following a further increase of the Ce dose. Combined with the results of TEM observation, it was assumed that a solid solution of Fe-Ce is formed following the disappearance of the magnetite phase. Occurrence of a characteristic surface hydroxyl group (M-OH, metal surface hydroxyl, 1126 cm -1 ), which showed the highest band intensity in the solid solution state, was confirmed on the bimetal oxide adsorbent by FTIR. Quantificational calculation from the XPS narrow scan results of O(1s) spectra also indicated that the formation of the bimetal Fe-Ce08 was composed of more hydroxyl (30.8%) than was the formation of CeO 2 and Fe 3 O 4 (12.6% and 19.6%). The results of adsorption tests on Fe-Ce08 at different As(V) concentrations indicated that both the integral area of the As-O band at 836 cm -1 and the As(V) adsorption capacity increased almost linearly with the decrease of the integral area of M-OH bands at 1126 cm -1 , proving that the adsorption of As(V) by Fe-Ce08 is mainly realized through the mechanism of quantitative ligand exchange. The atomic ratio of Fe on Fe-Ce08 decreased from 20.1% to 7.7% with the increase of the As atom ratio from 0 to 16% after As(V) adsorption, suggesting that As(V) adsorption might be realized through the replacement of the M-OH group of Fe (Fe-OH) with arsenate. The well splitting of three υ 3 bands at As-O band (836 cm -1 ) of FTIR and the hydroxyl ratio (1.7) of Fe-Ce08 calculated from the XPS results suggested that the diprotonated monodentate complex (SOAsO(OH) 2 ) is possibly dominant on the surface of Fe-Ce08.

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Section: Resultssupporting

confidence: 89%

“…They have attracted attention because of their relatively high adsorption capacities (6,7). The relatively small ionic potential and strong basicity of rare earth ions results in a strong tendency to dissociate OH groups into hydroxyl ions (6).…”

Section: Introductionmentioning

confidence: 99%

Arsenate Adsorption on an Fe−Ce Bimetal Oxide Adsorbent: Role of Surface Properties

Zhang

Yang

Dou

et al. 2005

Environ. Sci. Technol.

511

247

View full text Add to dashboard Cite

show abstract

“…effluent pH rose from the initial value of 5.0-6.2 following adsorption for 24 h in most of our experiments. The FTIR data and pH increase in the effluent indicate that substitution of M-OH groups by As(V) ions plays a very important role in the adsorption mechanisms of Ce-Fe adsorbent (Tokunaga et al, 1995). In an article reported by Goldberg and Johnston (2001), the positions of the As-O bands of a 0.1 M As(V) solution in the IR spectrum occurred at 878 and 907 cm À1 under pH 5.…”

Section: Adsorption Mechanismsmentioning

confidence: 93%

“…However, the problems including the need for pH adjustment, the relatively low adsorption capacity, and aluminum dissolution have prevented activated alumina from wider applications. It has been reported that the hydrous oxides of rare earth elements have a high affinity for such hazardous anions as arsenate, fluoride and phosphate (Hideaki et al, 1987;Tokunaga et al, 1995Tokunaga et al, , 1997. Tokunaga et al (1995) compared the removal of fluoride by multivalent metals such as Al(III), Y(III), La(III), Ce(III/IV), and Zr(IV) in the form of oxides, hydrous oxides and basic carbonates, and found that hydrous Ce(IV) oxide was the most effective one for removing fluoride without significant dissolution even at pH 2.…”

Section: Introductionmentioning

confidence: 99%

Arsenic(V) removal with a Ce(IV)-doped iron oxide adsorbent

2003

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“…The surface hydroxyl groups on metal oxides are considered as the most abundant and active adsorption sites for adsorption of anions from water [28][29][30]. In our previous studies [6,7] the surface acidity and formation of surface hydroxyl groups of the Fe-Ce have been provide to the interpretation of the adsorption behaviors.…”

Section: Surface Active Sites For Arsenate Adsorptionmentioning

confidence: 99%