However a fluoride removal method which is low cost safe environment friendly and can be used by a layman without requiring power is still not available recently reWe ported a fluoride removal technique based on phosphoric acid crushed limestone treatment PACLT which meets most of the above mentioned requirements Gogoi 2015
With a fourfold increase in the selective fluoride removal capacity of limestone to mg/g phosphoric acid PA enhanced limestone has been found to be a competent adsorbent material for
The rocks identified as KIT1 and KSS showed an increasing removal trend alongside decreasing particle size; the highest removal 65% was obtained with KIT1 from a solution that contained 4 mg/L fluoride and the smallest particle size 63 125 μm while KSS only reached 22% removal under the same final concentration one that complied with
Recently we reported a fluoride removal technique in which fluoride containing water is acidified with phosphoric acid PA and allowed to react with crushed limestone bed which removes fluoride from initial 10 mg L −1 to as low as mg L −1 [31] The required concentration of PA to remove fluoride is also very low compared to that of other edible acids
For efficient fluoride removal it requires more time about 20 hr because limestone dissolutes in small amounts at neutral pH In this work two common laboratory acids were added to the fluoride water before filtration through the limestone column and it was found that in the presence of acid the removal capacity of limestone not only
Development of a limestone based ballasted material for enhanced co removal of turbidity and fluoride from coal mine water An efficacy study They found that the fluoride removal rate of this material ranged between and % and that the adsorption process conformed to the Freundlich isotherm Chen et al [21] synthesized an
With all limestone samples defluoridation increased with increasing [PA] 0 and decreasing [F] 0 Fluoride removal and pH of treated water attained stability within 3 h The influence of coexisting anions on fluoride removal was low for all limestone samples and
Download Table Chemical composition of limestone from publication Fluoride removal from water using crushed limestone An examination of defluoridation by industrial grade limestone indicated
The mechanism of fluoride removal in this process consists of a combination of precipitation of calcium fluoride and adsorption of fluoride ions on the limestone surface [17] [18] The precipitation of fluoride from drinking water using calcium and phosphate salts such as calcium fluoride and/or fluorapatite FAP is theoretically feasible
Jain and Jayaram examined hydroxide impregnated limestone A1LS for fluoride removal from real water Due to the dissolution of the alumina in the acidic medium the pH of the alumina decreased to 2 The maximum adsorption capacities of the limestone and AlLS adsorbents were found to be mg/g and mg/g
At present absorbents such as hydroxyapatite activated alumina limestone activated carbon zeolite and calcite were commonly used to remove F from wastewater by their well adsorption ability [7] [8] [9] Constructed wetlands CWs was widely used in the advanced treatment of sewage [10] [11] with the advantages of low cost simple operation and high
The influence of coexisting anions on fluoride removal was low for all limestone samples and followed the order sulfate > chloride > nitrate The surface area and total pore volume above m²
The adsorption kinetics of fluoride onto limestone LS and Mg OH 2 amended LS were investigated using batch adsorption technique Data were best fitted to second order and Elovich models The Mg OH 2 ameded LS showed substantial increases in F− adsorption relative to native LS Similarity of ionic radii and charge of both F− and OH− were hypothesized to be
Fluoride contamination of groundwater both anthropogenic and natural is a major problem worldwide In this study fluoride removal by crushed limestone 99% pure calcite was investigated by batch studies and surface sensitive techniques from solutions with fluoride concentrations from 150 micromol/L 3 mg/L to 110 mM approximately 2100 mg/L
In this PA enhanced limestone defluoridation PAELD technique fluoride is removed from mM to μM in 3 h with near neutral final pH The presence of PA increases the fluoride removal capacity of limestone to mg/g compared to mg/g
With a fourfold increase in the selective fluoride removal capacity of limestone to mg/g phosphoric acid PA enhanced limestone has been found to be a competent adsorbent material for fluoride removal The PA enhanced limestone has been characterized and its fluoride sorption has been studied using various models The removal of
A two column limestone reactor has been designed to reduce fluoride concentrations from wastewaters to below the maximum contaminant level MCL limit of 4 mg/L The reactor functions by forcing calcite CaCO3 to dissolve and fluorite CaF2 to
Murutu et al 2012 used limestone derived apatite LDA for removal of fluoride from drinking water in batch mode The adsorbent was prepared by reacting with orthophospho ric acid The
Among several treatment technologies applied for fluoride removal adsorption process has been explored widely and offers satisfactory results especially with mineral based and/or surface modified adsorbents Jain and Jayaram [69] used aluminium hydroxide impregnated limestone A1LS for the efficient removal of fluoride from contaminated
A limestone reactor for fluoride removal from wastewaters Reardon ; Yanxin Wang Environmental Science and Technology 34 15 47 53 2000 ISSN/ISBN 0013 936X DOI /es990542k Accession 009750770 Article emailed within 0 6 h Buy Now for $ Payments are secure & encrypted
treatment with crushed limestone where fluoride was removed by both precipitation of fluorite and adsorption of fluoride on limestone surface21 33 37 However fluoride removal by these methods is associated with one or more shortcomings such as high operational and maintenance costs low capacity of adsorbent frequent replacement of
The presence of PA increases the fluoride removal capacity of limestone to mg/g compared to mg/g reported in its absence The changes in fluoride removal with variation in initial PA concentration initial fluoride concentration and the final pH have been found to be statistically significant with p <
Jain and Jayaram examined hydroxide impregnated limestone A1LS for fluoride removal from real water Due to the dissolution of the alumina in the acidic medium the pH of the alumina decreased to 2 The maximum adsorption capacities of the limestone and AlLS adsorbents were found to be mg/g and mg/g
Local limestone has fluoride removal abilities by phosphoric acid PA local crushed Limestone treatment PACLT with the treated water conforming to WHO guidelines for Fluoride in drinking water
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