Defluoridation of drinking water using chitin, chitosan and lanthanum-modified chitosan

Kamble, Sanjay P.; Jagtap, Sneha; Labhsetwar, Nitin; Thakare, Dilip; Godfrey, Sam; Devotta, S.; Rayalu, Sadhana

doi:10.1016/j.cej.2006.10.032

Cited by 214 publications

(101 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Sodium fluoride (NaF) stock solution of 1000 mg/L was prepared by dissolving 2.21 g of NaF salt in deionised water, and any subsequently required fluoride solutions were prepared by diluting the stock solution. The clay mineral was activated by agitating with 1 M sodium chloride (NaCl) in the ratio of 1:10 before modification, while silver nitrate (AgNO 3 ) was used to test the presence of any excess chloride after the activated clay was washed with deionised water. Hydrochloric acid (0.1 M HCl) and sodium hydroxide (0.1 M NaOH) were used to adjust the pH.…”

Section: Methodsmentioning

confidence: 99%

“…After the surface of the adsorbent is completely occupied, no further adsorption of fluoride from solution takes place. The linear form of the Langmuir equation is represented by Equation (3).…”

Section: Adsorption Isothermmentioning

confidence: 99%

“…Thus the World Health Organization (WHO) has specified the permissible limit of fluoride in potable water as 1.5 mg/L [2]. The occurrence of high fluoride in groundwater in particular has led to the development of defluoridation techniques based on the concepts of adsorption [3], precipitation [4], and membrane processes [5]. Adsorption is the most appropriate method because it has a combination of affordability and effectiveness [6].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Fluoride Sorption Efficiency of Vermiculite Functionalised with Cationic Surfactant: Isotherm and Kinetics

2016

View full text Add to dashboard Cite

Abstract:Groundwater is a major source of water, especially in rural communities. The presence of excess fluoride in groundwater has been a health concern for many decades because it causes fluorosis. The persistence of this problem led to the development of several approaches for reducing fluoride in groundwater to ≤1.5 mg/L, which is the World Health Organization's (WHO) permissible limit. Despite recorded success in fluoride reduction, drawbacks such as cost and efficiency have remained apparent, thus necessitating further research on defluoridation. This paper aims at assessing the defluoridation capacity of a clay mineral, vermiculite, when modified with the cationic surfactant hexadecyltrimethylammonium bromide. The effects of experimental parameters such as pH, agitation time, mass of adsorbent, and temperature were examined to determine the most favourable adsorption conditions. Using batch technique, the results showed a fluoride sorption of 51% from an 8 mg/L fluoride solution. The adsorption conformed more to Freundlich than Langmuir isotherm with an adsorption capacity of 2.36 mg/g, while the kinetics conformed to a pseudo-second-order reaction. pH emerged as the most influential factor in optimisation. The findings of this study indicated that modified vermiculite could be efficient in reducing fluoride in groundwater to more tolerable limits, but requires adequate pH control.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Adsorption Isothermmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Fluoride Sorption Efficiency of Vermiculite Functionalised with Cationic Surfactant: Isotherm and Kinetics

2016

View full text Add to dashboard Cite

show abstract

“…Among various methodologies, adsorption is found to be more appropriate and attractive in the application. Inorganic metal oxides, organic adsorbents and other low cost materials have been proposed for fluoride removal [1,2,7,12]. Among these adsorbents, alumina is the most widely used adsorbent, but its further application is limited by the low adsorption capacity at neutral pH, poor adsorption kinetics and the difficulties of regeneration [2,[13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Adsorption of fluoride onto different types of aluminas

Gong

Liu

et al. 2012

Chemical Engineering Journal

117

View full text Add to dashboard Cite

a b s t r a c tIn this study, five aluminas were synthesized at different pH and calcination temperatures, and the surface properties and defluoridation performance of aluminas were investigated. Characterization of XRD showed that five aluminas were poorly crystallized with different phases and their anion exchange capacity and the point of zero charge varied with the species of aluminas. The batch experiments (thermodynamics, kinetics and the effect of pH) were conducted to evaluate the fluoride adsorption behavior of different aluminas. For all aluminas, both Langmiur and Freundlich models fitted the adsorption isotherms well and the calculation of thermodynamics showed that adsorption was spontaneous and endothermic; the kinetics was well described by the pseudo-second-order model and the weak acidic pH favored the fluoride adsorption. Acidity/basicity of alumina exhibited significant effect on the behaviors of adsorption and the process of ion exchange in fluoride removal. Acidic alumina exhibited higher ion exchange capacity, more positively charged surface, and better defluoridation performance (higher adsorption capacity and quicker removal of fluoride) than basic alumina. Acidic alumina also showed higher efficiency when treating natural ground water without pH adjustment. The difference in the adsorption properties was ascribed to the different exchange sites and the different behaviors of anion exchange. In the case of acidic alumina, more Cl − was exchanged with fluoride and the adsorption/release of OH − was dependent on the initial fluoride concentration. For basic alumina most of exchange sites were provided by OH − and fluoride was removed through the exchange between fluoride and OH − .

show abstract

“…Although direct comparison of the calixpyrrole with other materials [36][37][38][39][40][41] is difficult owing to the different applied experimental conditions, it was found, in general, that the removal capacity of the calixpyrrole (0.4 mg/g) for fluoride ions is comparable with that of other materials and in fact greater than certain adsorbents (Table 4). It is well known that the properties of an ion in a solution are determined mainly by ion-solvent and ion-ion interactions [42,43].…”

Section: Comparison With Alternative Materialsmentioning

confidence: 97%

Calix[4]pyrrole macrocycle: Extraction of fluoride anions from aqueous media

2012

View full text Add to dashboard Cite

KEYWORDSSolid-phase extraction of fluoride anions by calixpyrrole macrocycle (CP) from aqueous media has been studied using the batch method. Various significant extraction parameters like initial concentration of the anion, extraction time, concentration of the calixpyrrole, pH and temperature were evaluated. Langmuir, Freundlichand, Dubinin-Redushkevish (D-R) isotherms and coefficients were used to analyze the equilibrium data. The amount of fluoride anion extracted per unit of the CP was found to be 0.40 mg/g at 298 K from 19 mg/L aqueous solution of fluoride anions. The mean free energy calculated from D-R model for the removal of fluoride anions by the CP was found to be 10.0 kJ/mol, indicating that chemisorption is involved in the extraction process. The data were also fitted to kinetic models such as pseudo first order and pseudo second order. The removal of fluoride anions increased with increasing temperature indicating the endothermic nature of the extraction process. The present method has been compared with the previous methods.

show abstract

Defluoridation of drinking water using chitin, chitosan and lanthanum-modified chitosan

Cited by 214 publications

References 8 publications

Fluoride Sorption Efficiency of Vermiculite Functionalised with Cationic Surfactant: Isotherm and Kinetics

Fluoride Sorption Efficiency of Vermiculite Functionalised with Cationic Surfactant: Isotherm and Kinetics

Adsorption of fluoride onto different types of aluminas

Calix[4]pyrrole macrocycle: Extraction of fluoride anions from aqueous media

Contact Info

Product

Resources

About