Extraction chromatographic method of preconcentration and separation of fluoride with high molecular mass liquid anion exchanger, Aliquat-336

A selective method has been developed for the extraction chromatographic separation of fluoride with Aliquat-336 (liquid cation exchanger) coated on silanised silica gel. Its quantitative extraction has been achieved in HCl medium at 0.1-0.3 M range. The effects of acid with different concentrations, flow-rate, stripping agents on extraction and elution have been investigated. Exchange capacity and break-through capacity of the prepared exchanger at different temperatures with respect to fluoride have been determined. The extraction equilibrium constant (K ex ) and different standard thermodynamic parameters have also been calculated by temperature variation method. Effect of influent concentration and influent volume on preconcentration factor (PF) has been investigated. Fluoride has been separated from synthetic binary and multi-component mixtures containing various anions associated with it in environmental samples. The method effectively permits sequential separation of fluoride from synthetic mixture containing its congeners, chloride, bromide and iodide of analytical group. The method was found effective for removal and recovery of fluoride from industrial waste and environmental samples following its preconcentration on the column. A plausible mechanism for the extraction of fluoride has been suggested.