ABSTRACT
58Drinking water is the major source of fluoride intake. The fluoride content in drinking water may be beneficial or detrimental depending on its concentration. The presence of excess fluoride (>1.5 mg/L) level in drinking water leads to fluorosis. The impact of fluoride in drinking water is a major concern in developing countries like India where around 17 states are affected by fluorosis. As there is no remedy for fluorosis, defluoridation of drinking water is one of the options to reduce the fluoride concentration in water. The creation of awareness among the people in rural areas is the best possible way to tackle this problem. Though various treatment techniques like precipitation, ion-exchange, adsorption, reverse osmosis, electrodialysis, Donnan dialysis, and nanofilteration have been suggested for fluoride removal, adsorption seems to be effective, eco-friendly, and economical one. Various adsorbents have been reported for fluoride removal, but each of them possesses own advantages and limitations. Most of the reports are academic oriented, but only few reports are available for technology development. Polymeric materials are widely used for water treatment, and they possess various advantages over the other adsorbent materials. This review focuses exclusively on the eco-friendly materials like low-cost inorganic materials, biopolymers, and biopolymeric composites for the defluoridation of water. The fluoride selectivity of the biopolymers/composites will be enhanced by chemical modifications like functionalization, metal ion incorporation, etc. A comparison of the adsorption capacity of various low-cost inorganic adsorbents, biopolymers, and biopolymeric composites were made.
