Article

Fluoride in drinking water and its removal

Centre for Rural Development and Technology, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi, India.
Journal of Hazardous Materials (Impact Factor: 4.33). 10/2006; 137(1):456-63. DOI: 10.1016/j.jhazmat.2006.02.024
Source: PubMed

ABSTRACT Excessive fluoride concentrations have been reported in groundwaters of more than 20 developed and developing countries including India where 19 states are facing acute fluorosis problems. Various technologies are being used to remove fluoride from water but still the problem has not been rooted out. In this paper, a broad overview of the available technologies for fluoride removal and advantages and limitations of each one have been presented based on literature survey and the experiments conducted in the laboratory with several processes. It has been concluded that the selection of treatment process should be site specific as per local needs and prevailing conditions as each technology has some limitations and no one process can serve the purpose in diverse conditions.

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Available from: Meenakshi Arora, Jul 01, 2015
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    • "The pollution is believed to have further aggravated due to extensive groundwater abstraction (Mukherjee et al., 2011). High concentrations of groundwater fluoride have also been observed, mostly in the crystalline aquifers in parts of 19 states (Maheshwari, 2006; CGWB, 2015). Elevated levels of groundwater iron (Fe) and nitrate (NO 3 "
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    ABSTRACT: The Indian Sub-Continent is one of the most densely populated regions of the world, hosting ∼23% of the global population within only ∼3% of the world's land area. It encompasses some of the world's largest fluvial systems in the world (River Brahmaputra, Ganges and Indus Basins), which hosts some of the highest yielding aquifers in the world. The distribution of usable groundwater in the region varies considerably and the continued availability of safe water from many of these aquifers (e.g. Bengal Basin) is constrained by the presence of natural contaminants. Further, the trans-boundary nature of the aquifers in the Indian Sub-Continent makes groundwater resource a potentially politically sensitive issue, particularly since this region is the largest user of groundwater resources in the world. Indeed, there is considerable concern regarding dwindling well yield and declining groundwater levels, even for the highly productive aquifers. Though irrigation already accounts for >85% of the total ground water extraction of the region, there is a mounting pressure on aquifers for food security of the region. Highly variable precipitation, hydrogeological conditions and predicted, impending climate change effects provide substantial challenges to groundwater management. The observed presence of natural groundwater contaminants together with the growing demand for irrigated food production and predicted climate change further complicate the development of strategies for using groundwater resources sustainably. We provide an introduction and overview of 11 articles, collated in this special issue, which describe the current condition of vulnerable groundwater resources across the Indian Sub-Continent.
    04/2015; 19. DOI:10.1016/j.ejrh.2015.03.005
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    • "Activated alumina has been widely employed for fluoride removal process [13] primarily for its ready availability, low cost and high removal efficiency. The process is however highly pH specific as at high pH (>7), silicate and hydroxide interfere appreciably in fluoride adsorption while at low pH (<5) activated alumina gets dissolved in acidic medium leading to loss of adsorbent [14]. Small ionic size coupled with high electronegativity implies that the fluoride ion has an appreciable affinity for multivalent cations like Al(III), Fe(III), and Zr(IV) [15]. "
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    ABSTRACT: Novel surface modified hydrous zirconium oxide with b cyclodextrin composite (CY-HZO) preparation. Significantly higher capacity of fluoride adsorption of CY-HZO than pristine HZO. Efficient, economical and eco-friendly fluoride remediation possible. Fluoride adsorption by CY-HZO via ion-exchange. About 95% reactivation of used CY-HZO is possible with 3 M NaOH. a b s t r a c t Surface modified hydrous zirconium oxide (HZO) with b-cyclodextrin (b-CD) material (CY-HZO) was characterized as micro-structured (150 nm), predominantly amorphous with irregular and undulated surface morphology using analytical tools such as XRD, SEM, TEM, AFM,BET surface analysis etc. Too high surface site concentrations of CY-HZO (6300 nm À2) compared to pristine HZO (26 nm À2) is owing to the abundance of surface –OH groups afforded by b-CD, which plays a decisive role in enhancing fluoride adsorption power of HZO. Fluoride adsorption over CY-HZO shows a discernible rise up to a pH $ 5.0, and declines sharply at pH > 6.0. Kinetically pseudo second order type fluoride adsorption reactions with CY-HZO and HZO were isothermally Langmuir type but endothermic with CY-HZO and exothermic with HZO. But both were spontaneous (ÀDG 0 = 1.78, 2.06 & 5.18 for CY-HZO and 3.14, 3.0 & 2.66 for HZO at T = 303, 318 and 333 K). Langmuir capacity (q m , mg g À1) of CY-HZO (31.45) is significantly higher than HZO (22.45) at 303 K. About 95% of the adsorbed fluoride could be released from CY-HZO surface by 3.0 M NaOH solution. Thus, CY-HZO should be a more potent material than HZO for fluoride removal from aqueous media. Ó 2014 Elsevier B.V. All rights reserved.
    Chemical Engineering Journal 03/2015; 263:220-230. DOI:10.1016/j.cej.2014.11.039 · 4.32 Impact Factor
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    • "Although numerous defluoridation methods have been introduced to reduce fluoride from drinking water to acceptable or non-harmful levels, most of these methods are broadly based on precipitation and adsorption techniques (Mohapatra et al. 2009). Reverse osmosis, electrodialysis , ion exchange, nanofiltration, limestone reactor and use of activated alumina are among the other techniques that are used to defluoridate contaminated water (Amor et al. 1998; Maheshwari 2006; Mohapatra et al. 2009). Since most of high-fluoride groundwater is reported among communities with low socioeconomic status (Levy 2005), expensive defluoridation methods cannot be used at the household level. "
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    ABSTRACT: Natural apatite from Eppawala located in the north central province of Sri Lanka was investigated for its ability to adsorb fluoride from aqueous solutions under laboratory conditions to develop an inexpensive and environmentally friendly adsorbent material. The adsorption of fluoride was evaluated as a function of pH, adsorbent dosage, contact time and initial fluoride concentrations. The solid materials were characterized using FTIR and XRD methods and their geochemical composition was obtained from XRF analyses. The adsorption studies were carried out under controlled conditions in which the fluoride activities of the solution were measured using an ion-selective electrode. The fluoride adsorption onto apatite is strongly pH dependent and the highest fluoride removal was observed at pH 6.0, while adsorption decreases both at low and high pH levels. The percentage fluoride removal increases with the absorbent dosage mainly due to increasing the number of adsorption sites, but the optimum adsorption can be obtained using small initial amounts of apatite in the suspension. The sorption process was very rapid and the maximum adsorption was achieved within the first 10 min in a solution containing 15.0 mg/L fluoride at pH 6.0. The kinetic studies showed that the fluoride removal process follows pseudo-second-order kinetics. The Langmuir isotherm best fitted (R 2 = 0.9537) with the adsorption over a range of fluoride concentrations from 5.0 to 25.0 mg/L. The monolayer coverage of fluoride on apatite was estimated as 0.212 mg/g. The simulated experimental conditions were tested for natural water with high fluoride levels with promising results and hence the results obtained from this study can be used to design an inexpensive, easy to use and environmentally friendly method for removal of fluoride in water supplies at village level.
    Environmental Earth Sciences 01/2015; 73(12). DOI:10.1007/s12665-014-3998-7 · 1.77 Impact Factor
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Questions & Answers about this publication

  • Ljubomir Jacić added an answer in Toothpastes:
    Should we still accept flouride to be added to our toothpaste and to the water we drink in our homes?

    Fluoride toothpastes sold in the United States bear the following poison warning:

    “WARNING: Keep out of reach of children under 6 years of age. If you accidentally swallow more than used for brushing, seek professional help or contact a poison control center immediately.”

    Small doses (0.1 to 0.3mg,kg) of fluoride can induce symptoms of acute fluoride toxicity.  A child weighing 10 kilograms,  can suffer symptoms of acute toxicity by ingesting just 1 to 3 milligrams of fluoride in a single sitting.

    Source: http://fluoridealert.org/studies/acute03/

    Ljubomir Jacić · Technical College Požarevac

    Dear @Vilemar, different oppinions among ordinary people and the experts! "...The daily supplementation with fluoride is undoubtedly an important preventing factor in protecting teeth from caries, and, as an important mitogenic stimulus for osteoblasts, it may enhance mineral deposition in bone, but on the other hand fluoride, above a threshold concentration, has been demonstrated to be toxic..." Here are some good research about!

    The attached paper on toothpastes on the Belgian Market brings very good methodology and analysis!