High efficient removal of fluoride from aqueous solution by a novel hydroxyl aluminum oxalate adsorbent

摘要

A novel adsorbent, hydroxyl aluminum oxalate (HAO), for the high efficient removal of fluoride from aqueous solution was successfully synthesized. The adsorbent was characterized and its performance in fluoride (F-) removal was evaluated for the first time. Kinetic data reveal that the F- adsorption is rapid in the beginning followed by a slower adsorption process; 75.9% adsorption can be achieved within 1 min and only 16% additional removal occurred in the following 239 min. The F- adsorption kinetics was well described by the pseudo second-order kinetic model. The calculated adsorption capacity of this adsorbent for F- by Langmuir model was 400 mg g(-1) at pH 6.5, which is one of the highest capabilities of today's materials. The thermodynamic parameters calculated from the temperature-dependent isotherms indicate that the adsorption reaction of F- on the HAO is a spontaneous process. The FT-IR spectra of HAO before and after adsorbing F- show adsorption mechanism should be hydroxyl and oxalate interchange with F-. (C) 2015 Elsevier Inc. All rights reserved.