Removal of fluoride ions from aqueous solution by the calcination product of Mg–Al–Fe hydrotalcite-like compound

Ma, Wei; Zhao, Nannan; Yang, Gang; Tian, Liyan; Ren, Wei

doi:10.1016/j.desal.2010.09.045

Cited by 124 publications

(44 citation statements)

References 35 publications

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“…For NiAl-T, the surface area is sharply increased from 90 m 2 g -1 to a value greater than 100 m 2 g -1 after calcination. It was assumed that a porous structure is developed in the calcined sample during removal of water and carbonate from the interlayer space by the transformation of CO 3 2-to CO 2 [41][42][43]. The sample calcined at 300°C (NiAl-300) presents the highest surface area (236 m 2 g -1 ), while S BET value decreased gradually with increasing calcination temperature.…”

Section: Resultsmentioning

confidence: 99%

Effect of the Ni/Al ratio of hydrotalcite-type catalysts on their performance in the methane dry reforming process

et al. 2015

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Hydrotalcite-type solids of the form NiAl-R, where R refers to the ratio of Ni to Al (R = 2, 3, 5, 8, and 10), were successfully synthesized following co-precipitation method at pH = 12. The obtained solids were calcined at 800°C, except for NiAl-R 2 where calcination was performed at temperatures ranging between 300 and 800°C. Following calcination, the resulting materials were evaluated for their catalytic activity and stability during the process of dry reforming of methane. Factors affecting the catalytic activity of the obtained materials such as the ratio R and calcination temperature were also studied. Prior to calcination, X-ray diffraction analyses clearly illustrated the typical hydrotalcite structure of the synthesized materials (when R B 5). On the other hand, calcination at various temperatures prompted decomposition of all solids to form NiO, with exception to NiAl-R 2 , which upon calcinations at 800°C was decomposed to form NiO and a second phase spinel containing NiAl 2 O 4 . The chemical composition of the obtained solids was determined by atomic absorption spectroscopy. Further characterization was performed using several techniques, including: surface area measurements (S BET ), scanning electron microscopy, Fourier transform infrared spectroscopy and thermogravimetric analysis. The reducibility of nickel species was studied via temperatureprogrammed reduction. The catalytic performance of the asprepared samples was studied for dry reforming of methane under atmospheric pressure at temperatures ranging between 400 and 700°C. The catalytic activity of the designed substances highlighted the importance of molar ratios i.e. Ni 2? / Al 3? on the success of the overall dry reforming of methane process. The catalytic activity of the synthesized materials was also found to be directly proportional to the ratio of Ni/ Al as well as the calcination temperature, with exception to NiAl-R 2 which was found to exhibit the highest activity of all. The latter observation was perhaps associated with the lower size of the crystalline particles in conjunction with the presence of a second phase containing NiAl 2 O 4 . In this study, it is shown that the calcination temperature has a significant effect on the catalytic property and the crystallite size of the metal.

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Section: Resultsmentioning

confidence: 99%

Effect of the Ni/Al ratio of hydrotalcite-type catalysts on their performance in the methane dry reforming process

et al. 2015

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“…Anions such as sulfate, nitrate, carbonate, chloride, bicarbonate, and phosphate influence adsorption by adjustment of the electrostatic charge at the solid surface because of the same negative ions [11,[56][57][58][59][60][61]. The effects of anions on fluoride removal were reported by [40,[62][63][64][65][66]. Both direct and indirect effects of these anions are influenced by pH, anions' concentrations, and intrinsic binding affinities [42,59].…”

Section: Adsorption Methods For Arsenic and Fluoride Removalmentioning

confidence: 99%

“…The tendency of the anions to form inner-sphere complexes was reported by [28,29,32,63,170,174,175,177,178,[180][181][182][183]. Chloride ions formed outer-sphere surface complexes and had a minor effect on fluoride adsorption; thus they are less absorbed on the absorbent surface [65]. Anion affinity for a surface site is associated with the physicochemical characteristics of the adsorption mechanism [40,147,179].…”

Section: Effects Of Anion Cation and Organicmentioning

confidence: 99%

“…Matter on Fluoride Removal [40,62,63,65,66]. In fluoride adsorption, it is expected that the presence of anions in solution would enhance coulombic repulsion forces between the anions and fluoride or would compete with fluoride for the active adsorption sites and therefore fluoride adsorption is reduced or increased [66,135,136,178,179].…”

Section: Effects Of Anion Cation and Organicmentioning

confidence: 99%

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A Comparative Study on Removal of Hazardous Anions from Water by Adsorption: A Review

John

David

Mmereki

2018

International Journal of Chemical Engineering

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This paper presents a comparative review of arsenite (As(III)), arsenate (As(V)), and fluoride (F − ) for a better understanding of the conditions and factors during their adsorption with focus on (i) the isotherm adsorption models, (ii) effects of pH, (iii) effects of ionic strength, and (iv) effects of coexisting substances such as anions, cations, and natural organics matter. It provides an indepth analysis of various methods of arsenite (As(III)), arsenate (As(V)), and fluoride (F − ) removal by adsorption and the anions' characteristics during the adsorption process. The surface area of the adsorbents does not contribute to the adsorption capacity of these anions but rather a combination of other physical and chemical properties. The adsorption capacity for the anions depends on the combination of all the factors: pH, ionic strength, coexisting substances, pore volume and particles size, surface modification, pretreatment of the adsorbents, and so forth. Extreme higher adsorption capacity can be obtained by the modification of the adsorbents. In general, pH has a greater influence on adsorption capacity at large, since it affects the ionic strength, coexisting anions such as bicarbonate, sulfate, and silica, the surface charges of the adsorbents, and the ionic species which can be present in the solution.

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“…The value of the pHpzc of the UmF adsorbent was determined using the modified pH drift method (Faria et al 2004;Zaini et al 2009;Ma et al 2011), in which 0.15 g of UmF were mixed with 50 mL of 0.01 M NaCl at different initial pH values. The initial pH of the solution was adjusted between 2 and 12 by the addition of a 0.1 M HCl or 0.1 M NaOH solution.…”

Section: Ir Spectroscopymentioning

confidence: 99%

Separation of Cr(VI) from aqueous solutions by adsorption on the microfungus Ustilago maydis

Serrano-Gómez

Olguín

2014

Int. J. Environ. Sci. Technol.

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Cr(VI) adsorption from aqueous solutions on the microfungus Ustilago maydis modified with formaldehyde (UmF) was studied as a function of the initial pH, contact time, chromium concentration and temperature. The pH results showed that Cr(VI) adsorption on UmF is higher at acidic pH values and decreases as the pH increases to alkaline values. Cr(VI) adsorption also depends on the chromium concentration and temperature. The Cr(VI) adsorption data as a function of concentration obey the Freundlich and Langmuir isotherms at pH values of 2 and 6.5. The maximum sorption capacity of UmF for Cr(VI) at pH 2 was 2.53 9 10 -3 mol/g (131.55 mg/g), which is significantly higher than that at pH 6.5 (0.33 9 10 -3 mol/g or 17.60 mg/g). The negative value of DH°and the positive values of DG°indicate that the chromium adsorption process is exothermic and nonspontaneous. The pHpzc value was 5 for UmF and it played a role in the Cr(VI) adsorption.

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Removal of fluoride ions from aqueous solution by the calcination product of Mg–Al–Fe hydrotalcite-like compound

Cited by 124 publications

References 35 publications

Effect of the Ni/Al ratio of hydrotalcite-type catalysts on their performance in the methane dry reforming process

Effect of the Ni/Al ratio of hydrotalcite-type catalysts on their performance in the methane dry reforming process

A Comparative Study on Removal of Hazardous Anions from Water by Adsorption: A Review

Separation of Cr(VI) from aqueous solutions by adsorption on the microfungus Ustilago maydis

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