Enhanced fluoride sorption by mechanochemically activated kaolinites

Meenakshi, Sankaran; Sundaram, C. Sairam; Sukumar, Rugmini

doi:10.1016/j.jhazmat.2007.08.031

Cited by 201 publications

(85 citation statements)

References 32 publications

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“…Nevertheless, the applicability of low-cost adsorbents is limited either due to their low removal capacity or lack of public acceptance. For instance, adsorption of fluoride using activated alumina (Ghorai and Pant 2005), bone char (Leyva-Ramos et al 2010), and clay materials (Meenakshi et al 2008) was investigated and none of them is used in household or large-scale application. Therefore, it is still essential to identify materials that are both effective and applicable in low-income communities.…”

Section: Introductionmentioning

confidence: 99%

Experimental evaluation of sorptive removal of fluoride from drinking water using iron ore

et al. 2014

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High concentrations of fluoride in drinking water is a public health concern globally and of critical importance in the Rift Valley region. As a low-cost water treatment option, the defluoridation capacity of locally available iron ore was investigated. Residence time, pH, agitation rate, particle size of the adsorbent, sorbent dose, initial fluoride concentration and the effect of co-existing anions were assessed. The sorption kinetics was found to follow pseudo-first-order rate and the experimental equilibrium sorption data fitted reasonably well to the Freundlich model. The sorption capacity of iron ore for fluoride was 1.72 mg/g and the equilibrium was attained after 120 min at the optimum pH of 6. The sorption study was also carried out at natural pH conditions using natural ground water samples and the fluoride level was reduced from 14.22 to 1.17 mg/L (below the WHO maximum permissible limit). Overall, we concluded that iron ore can be used in water treatment for fluoride removal in the Rift Valley region and beyond.

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Section: Introductionmentioning

confidence: 99%

Experimental evaluation of sorptive removal of fluoride from drinking water using iron ore

et al. 2014

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“…However, the slow rate of adsorption of commercially available activated alumina limits its use for treating large quantity of water [8,9]. In recent years, many efforts have been devoted to investigate and develop new fluoride adsorbent using various synthetic, naturally occurring and waste materials, such as fly ash [10], clay [11], hydrotalcite [12], zeolite [13], etc.…”

Section: Introductionmentioning

confidence: 99%

Enhanced fluoride adsorption using Al (III) modified calcium hydroxyapatite

Nie

Kong

2012

Journal of Hazardous Materials

182

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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.

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“…Kaolinite is a well-de ned 1:1-type phyllosilicate with the chemical composition Al 2 Si 2 O 5 (OH) 4 . [11][12][13] Although the adsorption capacity for inorganic anions onto kaolinite is relatively low when compared to iron oxides, kaolinite plays a certain role in the retention of inorganic uoride science it is widely distributed in natural environments. 8,11,12,14) Iron oxides and phyllosilicates are often simultaneously present in soils and sediments, where they tend to form binary systems by iron oxides coating on the surface of phyllosilicates.…”

Section: Introductionmentioning

confidence: 99%

“…[11][12][13] Although the adsorption capacity for inorganic anions onto kaolinite is relatively low when compared to iron oxides, kaolinite plays a certain role in the retention of inorganic uoride science it is widely distributed in natural environments. 8,11,12,14) Iron oxides and phyllosilicates are often simultaneously present in soils and sediments, where they tend to form binary systems by iron oxides coating on the surface of phyllosilicates. [13][14][15][16] The formation of iron oxide-phyllosilicate complexes has important in uences on the physical and chemical properties of the minerals in natural environments.…”

Section: Introductionmentioning

confidence: 99%

Binary Systems of Kaolinite and Hematite: Preparation, Characterization and Adsorption Characteristics for Fluoride

et al. 2016

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In soils and sediments kaolinite (Kao) and hematite (Hem) are often cemented together as binary systems, which have a signi cant in uence on the mobility of nutrients and pollutants in natural environments. In this study, the binary systems of kaolinite-hematite complex (KHC) and kaolinite-hematite mixture (KHM) were prepared, and the surface properties and uoride adsorption of the samples were investigated. Compared to KHM, the XRD peaks for both kaolinite and hematite in KHC were lower. The crystallinity of hematite in KHM and KHC was 94.13% and 80.99% respectively. This indicates that the surface of kaolinite in KHC was largely coated by poorly crystalline hematite, and the coating in KHM was relatively weak. The total pore volume of the samples followed the sequence of Hem > KHC > KHM > Kao, and the speci c surface area (SSA) decreased in the order of KHC > Hem > KHM > Kao. The isoelectric point (IEP) of Kao, Hem, KHM and KHC was 3.3, 7.6, 5.9 and 6.5, and the zeta potential at pH 5.5 was −18.6, 25.3, 2.8 and 10.3 mV, respectively. The uoride adsorption data of the samples were tted using one-site Langmuir, two-site Langmuir and Freundlich models, and results indicated that the binary systems possessed the surface with various adsorption sites for uoride. At pH 5.5, the adsorption capacity (q max ) of Kao, Hem, KHM and KHC was 1.92, 13.79, 7.48 and 10.46 mg·g −1 , respectively. Compared to the average of Kao and Hem, the q max of KHC increased signi cantly (P < 0.05), whereas that of KHM had no signi cant change (P > 0.05).

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Enhanced fluoride sorption by mechanochemically activated kaolinites

Cited by 201 publications

References 32 publications

Experimental evaluation of sorptive removal of fluoride from drinking water using iron ore

Experimental evaluation of sorptive removal of fluoride from drinking water using iron ore

Enhanced fluoride adsorption using Al (III) modified calcium hydroxyapatite

Binary Systems of Kaolinite and Hematite: Preparation, Characterization and Adsorption Characteristics for Fluoride

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