Combined use of calcium salts and polymeric aluminium hydroxide for defluoridation of waste waters

Removal of fluoride from water by carbon nanotube supported alumina

“…Ingesting water with fluoride concentrations below this level will cause dental cavities while higher than this limit can lead to skeletal abnormalities, dental fluorosis, and kidney disease [1]. Many methods have been developed to remove the excess fluoride from wastewater: precipitation with calcium and aluminum salts [2,3], adsorption by activated alumina [4], alum, charcoal [5], ion exchange and membrane processes such as reverse osmosis nanofiltration [6], electrodialysis [7] and Donnan dialysis [8]. Of these methods, adsorption is the most widely used method and exploitation of more cost-effective adsorbents for fluoride removal has been the aim of researchers.…”

Adsorption of fluoride from water by amorphous alumina supported on carbon nanotubes

“…Many methods have been adopted to remove the excess fluoride from drinking water: precipitation with calcium and aluminum salts [3,4], adsorption by activated alumina (AA) [5,6], alum, charcoal [7], ash [8], ion exchange and membrane processes such as reverse osmosis nanofiltration [9], electrodialysis [10] and Donnan dialysis [1,2]. Among these methods, the most commonly used one for fluoride removal from drinking water is adsorption by the AA, which has a good capacity and selectivity for fluoride removal.…”

A comparative study on the batch performance of fluoride adsorption by activated silica gel and activated rice husk ash

“…The experimental data was also applied to the pseudo-second-order kinetic model (Ho et al, 1999) given as t / q t = 1 / K 2 q e 2 + t / q e (6) For different concentration of fluoride, the fit of this model was controlled by each linear plot of t/qt versus t respectively. The constants can be calculated from slope and the intercept of the plots (Table 5).…”

“…But many epidemiological studies have shown possible adverse effects of the longterm ingestion of fluoride, even in the places where people are consuming water with fluoride content of 1.5 mg/L (Sujana and Anand, 2010). Membrane filtration (Ndiaye et al, 2005), precipitation (Parthasarathy et al, 1986), nanofiltration (Simons et al, 1993), ion-exchange (Ruixia et al, 2002), electrocoagualation flotation (Hu et al, 2005) and adsorption (Mohapatro et al, 2004) have been used for fluoride removal. Among these methods, adsorption techniques is the most effective and widely used methods, because its universal has a low maintenance cost, and is applicable for the removal of fluoride even at low concentration (Chen et al, 2010).…”