Enhanced fluoride removal from drinking water by magnesia-amended activated alumina granules

Maliyekkal, Shihabudheen M.; Shukla, Sanjay Kumar; Philip, Ligy; Nambi, Indumathi M.

doi:10.1016/j.cej.2007.09.049

Cited by 280 publications

(126 citation statements)

References 31 publications

Supporting

Mentioning

120

Contrasting

Unclassified

Order By: Relevance

“…Interference was observed on fluoride adsorption by CO 3 2− and PO adsorption capacity was reduced by 10% for an initial CO 3 2− and PO 4 3− concentration of 5 mM. The reduction in fluoride removal observed by the presence of CO 3 2− and PO 4 3− may be due to competition from these ions for active site [1,3,7].…”

Section: Adsorption Kinetics and The Effects Of Ph And Co-existing Anmentioning

confidence: 90%

“…Among these methods, membrane and ion exchange processes are not very common due to its high installation and maintenance cost, while chemical precipitation results in relatively higher residual fluoride concentration in the effluents [5,7]. Adsorption process is a widely accepted technique because of its ease of operation and cost-effectiveness [3].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Enhanced fluoride adsorption using Al (III) modified calcium hydroxyapatite

Nie

Kong

2012

Journal of Hazardous Materials

182

View full text Add to dashboard Cite

h i g h l i g h t sAl modified hydroxyapatite possessed a higher defluoridation capacity of 32.57 mg/g. Hydroxyl groups on the surface of Al-HAP was the adsorption sites for F − removal. Enhanced F − removal over Al-HAP was attributed to the modification with aluminum.a r t i c l e i n f o a b s t r a c tAluminum-modified hydroxyapatite (Al-HAP) was prepared and characterized using XRD and BET analyses. Al-HAP possessed higher defluoridation capacity (DC) of 32.57 mgF − /g than unmodified hydroxyapatite (HAP) which showed a DC of 16.38 mgF − /g. The effect of Al/Ca atomic ratio in Al-HAP, solution pH and co-existing anions was further studied. The results indicated that the adsorption data could be well described by the Langmuir isotherm model and the adsorption kinetic followed the pseudo-second-order model. The pH changes during the adsorption process suggested that the OH on the surface of Al-HAP was the adsorption sites. The more adsorption sites were formed on Al modified HAP, which possessed abundant surface hydroxyl groups, resulting in higher efficiency of F − removal. Thermodynamic parameters such as G• , H • and S • were calculated in order to understand the nature of adsorption process. The results revealed that the adsorption reaction was a spontaneous and endothermic process.

show abstract

Section: Adsorption Kinetics and The Effects Of Ph And Co-existing Anmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Enhanced fluoride adsorption using Al (III) modified calcium hydroxyapatite

Nie

Kong

2012

Journal of Hazardous Materials

182

View full text Add to dashboard Cite

show abstract

“…Recently, extensive studies have been performed by impregnating AA with alum, 8 manganese, 9-11 magnesium, 12 iron, 13,14 lithium 15 and lanthanum 16 to improve F adsorption. Among these methods, lanthanum (La) impregnation has been proved to be most promising because of its specic affinity for F. 16,17 Wasay et al were the rst to add La on AA by mixing 0.1 mm diameter AA particles with La solution at pH 7.5 for 48 h. The resulting material increased the F adsorption capacity from 3.31 mg g À1 to 6.23 mg g À1 .…”

mentioning

confidence: 99%

Synthesis, characterization and application of lanthanum-impregnated activated alumina for F removal

2013

View full text Add to dashboard Cite

Elevated fluoride (F) in groundwater presents an obvious environmental concern. Adsorption using activated alumina (AA) is currently the best available technology for F removal, despite its low efficiency, pH dependence, and aluminium (Al) release. The motivation for our study is to synthesise a new F adsorbent by impregnating commercially available granulated AA with lanthanum oxide (LAA), and to explore its F adsorption mechanism on the molecular scale. Five cycles of lanthanum impregnation on AA followed by calcination at 573 K increased the La content up to 19.1% and the F removal from 18.1% by pristine AA to 92.4% by LAA. The SEM, TEM, XRD, TGA, and EXAFS results demonstrated that the 5-20 nm thin flakes of LaOOH on LAA were in an amorphous form, with 7.6 oxygen atoms around each La. This LaOOH layer was uniformly distributed inside the micropores of the 1-3 mm AA granules.LAA exhibited four fold higher F adsorption capacity than AA in the pH range 3.9 to 9.6, with substantially reduced Al release. The ability to regenerate and reuse LAA makes it an attractive sustainable material. Multiple complementary spectroscopic analyses demonstrated that ligand exchange between F and surface hydroxyl groups is the mechanism for F adsorption on LAA. Our work improves the understanding of F interaction with metal oxides on the molecular scale and presents an alternative solution for elevated F water treatment.

show abstract

“…Therefore, it may be recommended to use waters only after reverse osmosis or any suitable treatment for removing nitrate and fluoride content to prevent adverse health effects. (Canter,1987 andMaliyekkal, et al, 2008).…”

Section: Discussionmentioning

confidence: 99%