Investigations on the kinetics and mechanisms of sorptive removal of fluoride from water using alumina cement granules

Ayoob, S.; Gupta, Ashok Kumar; Bhakat, P.B.; Bhat, Venugopal T.

doi:10.1016/j.cej.2007.08.029

Cited by 132 publications

(84 citation statements)

References 25 publications

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“…There is an assumption that low values of activation energy indicate diffusion controlled transport and a physical sorption process, whereas higher activation energy indicates chemisorption or surface controlled processes [43]. In accordance with other studies, an activation energy of 5-40 kJ mol -1 corresponds to physical sorption, while 40-800 kJ mol -1 corresponds to [44][45][46].…”

Section: Sorption Kinetics Study Of Metalloidssupporting

confidence: 58%

Sorption of V and VI group metalloids (As, Sb, Te) on modified peat sorbents

Ansone-Bertina

Kļaviņš

2016

Open Chemistry

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Abstract:The present work investigates arsenic, antimony and tellurium sorption using iron modified peat. The results were obtained using batch tests and the sorption was studied as a function of initial metalloid concentration, pH and sorption time, as well as the presence of competing substances. The obtained results indicate that modification of peat with Fe compounds significantly enhances the sorption capacity of the sorbents used for sorption of arsenic, antimony and tellurium. The optimal pH interval for the sorption of Sb(III) is 6.5-9 and for As(V) and Sb(V) -3-6, while As(III) and tellurium sorption using Fe-modified peat is favourable in a wider interval of 3-9. The presence of competing ions as well as HA affect sorption of metalloids on Fe-modified peat. A minor impact on the reduction of metalloid sorption was detected in the presence of nitrate, sulphate, carbonate and tartrate ions, while in the presence of phosphate and HA the sorption ability of metalloids can be considerably reduced. The obtained results of kinetic experiments indicate that sorption of metalloids on Fe-modified peat mainly occurs relying on mechanisms of physical sorption processes.Keywords: peat, sorbents, arsenic, antimony, tellurium, metalloids Environmental contextGrowing attention is being paid to environmental pollution with metalloids (As, Sb, Te) requiring new approaches for removal of these elements from water. The present work investigates arsenic, antimony and tellurium sorption using iron modified peat. Iron modified peat has high sorption capacity in respect to all environmentally relevant metalloid speciation forms [As(V), As(III), As(org.), Sb(III), Sb(V), Te(IV) and Te(VI)]. The sorption takes place according to mechanisms of physical sorption and is affected by pH of a solution as well as competing ions.

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Section: Sorption Kinetics Study Of Metalloidssupporting

confidence: 58%

Sorption of V and VI group metalloids (As, Sb, Te) on modified peat sorbents

Ansone-Bertina

Kļaviņš

2016

Open Chemistry

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“…It can be deduced that the disappearance of the 1120 cm -1 peak is due to fluoride adsorption on the corresponding hydroxyl site. Because -OH and F -have nearly the same size, they can exchange for each other, 8 and F -can be stably adsorbed. The capability of accepting or providing H + of the hydroxyl on the adsorbent surface can be determined through the titration of NaOH solution, and the results are shown in Figure 5.…”

Section: Examination Of the Effects Of The Surface Chargementioning

confidence: 99%

“…7 The development of socially acceptable and economical adsorbents to meet local community needs has become a focus of water treatment in the world. 8 Rare earth metal hydroxides/ oxides are potential adsorbents because of their strong affinity for fluoride. 9,10 However, rare earth metals are usually expensive, which restricts their use in the treatment of drinking water.…”

Section: Introductionmentioning

confidence: 99%

The Roles of the Surface Charge and Hydroxyl Group on a Fe−Al−Ce Adsorbent in Fluoride Adsorption

Wang

Chen

et al. 2009

Ind. Eng. Chem. Res.

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The roles of the surface charge and hydroxyl group on a Fe-Al-Ce adsorbent in fluoride adsorption were studied. Fluoride adsorption at different initial solution pH was investigated. An external voltage was applied to an adsorbent-coated electrode to examine the adsorption characteristics due to the surface charge. The capability of accepting or providing H + of the hydroxyl on the adsorbent surface was determined through the titration of NaOH solution, and the change of the hydroxyl before and after adsorption was analyzed by FTIR. Fluoride adsorption was rapid during the initial stage but slowed down later. Fluoride ions were transferred to the adsorbent surface by Coulombic attraction and/or thermal motion, forming a temporary and nonspecific adsorption. The enriched fluoride ions reacted with the hydroxyl groups on the adsorbent surface, forming a stable adsorption. The surface charge on the adsorbent and ion exchange between surface hydroxyl groups and fluoride ions have a large effect on the adsorption rate and efficiency.

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“…The kinetic equations, which are, Avrami ( Lopes et al, 2003), pseudo first-order (Largegren, S., 1898), pseudo-second order (Ho, Y.S., Mckay, G.M., 1999), Elovich ( Ayoob et al, 2008) and intra-particle diffusion model (Weber Jr. and Morris, 1963) are given in Table 1.…”

Section: Kinetic and Equilibrium Studiesmentioning

confidence: 99%