Removal of Fluoride from Spent Pot Liner Leachate Using Ion Exchange

Abstract

Spent pot liner (SPL), a hazardous solid waste produced at cell houses of aluminum smelters, is a potential source of fluoride pollution. Leachates collected from SPL disposal sites were found to contain fluoride at considerable concentration levels (up to 575 mgIL). This paper reports a study of selective fluoride removal following laboratory-prepared, ion-exchange treatment. Spent pot liner leachates were pretreated with lime to bring the fluoride level down to approximately 10 mgIL for economic and effective working of the ion exchanger. The detailed ion-exchange treatment study for removal of fluoride was carried out on synthetic SPL leachates and the optimum treatment thus developed was applied on natural SPL leachates.Bench-scale studies were carried out at various flow rates and pHs and in the presence of other ions commonly available in the SPL leachates. The prepared exchanger reduced the level of fluoride from approximately 10 mglL to less than I mgIL. Results indicate that the extraction was 100% up to 6-mUmin flow rate through the ion exchanger and it works efficiently in the pH range of 7 to 10. There is no effect of the other ions present in leachates on removal of fluoride. The exchanger has good capacity to exchange and can be recharged by eluting fluoride sorbed on the exchanger using two molar hydrochloric acid. Water Environ. Res., 71,36 (1999).

Removal of fluoride from polluted waters using active carbon derived from barks of Vitex negundo plant

“…A variety of treatment procedures have been reported for the removal of excess fluoride from polluted waters based on precipitation (Aldaco et al 2007;Akbar et al 2008;Reardon and Wang 2000;Cengeloglu et al 2002;Yadav et al 2006;Nawlakhe et al 1975;Saha 1993), ion exchange (Meenakshi and Viswanathan 2007;Castel et al 2000;Feng Shen et al 2003;Chubar et al 2005;Apambire et al 1997;Singh et al 1999), reverse osmosis (Sehn 2008;Simons 1993), Donnan dialysis (Tor 2007;Garmes et al 2002;Hichour et al 1999), electrodialysis (Lahnid et al 2008;Menkouchi et al 2007;Hichour et al 2000;Adikari et al 1989;Amer et al 2001), nanofiltration ), membrane-based methods (Dieye et al 1998;Mjengera and Mkongo 2003;Lhassani et al 2001;Mameri et al 2001), electrocoagulation (Hu et al 2003), and adsorption on to various adsorbents (Shihabudheen et al 2006;Onyango et al 2006;Tripathy et al 2006;Mohapatra et al 2004;Raichur and Jyoti Basu 2001). The choice of the method depends on conditions like area, concentration, availability of resources, etc.…”

Various Options for Removal of Fluoride from Drinking Water

“…During the years following the discovery of fluoride as the cause of fluorosis, extensive research has been done on various methods for removal of fluoride from water and wastewater. These methods are based on the principle of adsorption [33], ion-exchange [34], precipitation-coagulation [35,36], membrane separation process [37,38], electrolytic defluoridation [39], electrodialysis [40][41][42], etc.…”

Magnesium oxide entrapped Polypyrrole hybrid nanocomposite as an efficient selective scavenger for fluoride ion in drinking water

“…Certain technologies have been established for fluoride removal from water such as ion exchange, precipitation, nanofiltration, reverse osmosis, Donnan dialysis electrodialysis, and adsorption [4][5][6][7][8]. Several disadvantages, i.e.…”