Spent potlining (SPL) hazardous waste is a potentially valuable source of fluoride, which may be recovered through chemical leaching and adsorption with a selective sorbent. For this purpose, the commercially available chelating resin Purolite S950+ was loaded with lanthanum ions, to create a novel ligand-exchange sorbent. The equilibrium fluoride uptake behaviour of the resin was thoroughly investigated, using NaF solution and a simulant leachate of SPL waste. The resin exhibited a large maximum defluoridation capacity of 187 ± 15 mg g from NaF solution and 126 ± 10 mg g from the leachate, with solution pH being strongly influential to uptake performance. Isotherm and spectral data indicated that both chemisorption and unexpected physisorption processes were involved in the fluoride extraction and suggested that the major uptake mechanism differed in each matrix. The resin demonstrates significant potential in the recovery of fluoride from aqueous waste-streams.

Ion-exchange technology offers a low-energy potential route to the recovery of fluoride from aluminium industry leachate. This study presents an investigation into the kinetics of fluoride uptake from a simulant leachate and for comparison, from a simple NaF solution, using a lanthanum-loaded chelating resin. Experimental data were found to follow the Ho pseudo 2 nd -order rate law and the Elovich equation, suggesting that, although multiple uptake mechanisms occurred on heterogeneous binding sites, the process was chemical reaction-controlled. The maximum observed rate constants were calculated as 0.760 ± 0.01 g mg -1 min -1 (NaF solution) and 0.0724 ± 0.0125 mg -1 min -1 (leachate). However, the maximum calculated equilibrium uptake for the leachate was 26.9 ± 0.2 mg g -1 , which was almost twice as high as for NaF solution (14.0 ± 0.9 mg g -1 ).