Outstanding fluoride removal from aqueous solution by a La-based adsorbent.

A La-based adsorbent was prepared with La(NO 3 ) 3 ·6H 2 O, 2-methylimidazole and DMF via amide-hydrolysis and used for fluoride decontamination from aqueous water. The obtained adsorbent was lanthanum methanoate (La(COOH) 3 ). The effects of pH value, initial F - concentration and interfering ions on defluoridation properties of as-prepared La(COOH) 3 were assessed through batch adsorption tests. The adsorption kinetics, isotherm models and thermodynamics were employed to verify the order, nature and feasibility of La(COOH) 3 towards fluoride removal. The results imply that La(COOH) 3 is preferable for defluoridation over a wide pH range of 2 to 9 without interference. Simultaneously, the defluoridation process of La(HCOO) 3 accords to the pseudo-second order model and Langmuir isotherm, revealing chemical adsorption is the main control step. The maximum fluoride capture capacities of La(COOH) 3 at 30, 40 and 50 °C are 245.02, 260.40 and 268.99 mg g -1 , respectively. The mechanism for defluoridation by La(COOH) 3 was revealed by PXRD and XPS. To summarize, the as-synthesized La based adsorbent could serve as a promising adsorbent for defluoridation from complex fluoride-rich water.