Fluoride adsorption on carboxylated aerobic granules containing Ce(III)

Aerobic granules (AG) were carboxylated and Ce(III) was incorporated to obtain modified granuels (Ce(III)-MAG) for removal of fluoride from aqueous solutions. The Ce(III)-MAG was characterized by SEM, FTIR, XRD and pH and the introduction of carboxyl groups and Ce(III) was confirmed. The adsorption capacity of Ce(III)-MAG for fluoride was 45.80 mg/g at neutral pH, an increase of 359% compared to the capacity of pristine AG. Adsorption was highest at pH range of 3.0-5.0. A positive effect on fluoride removal in the order of K+ approximate to Mg2+ > Ca2+ > Na+ and a negative effect in the order of NO3- > Cl- > SO42- > HCO3- > PO43- was observed. Fluoride adsorption followed the Redlich-Peterson model and the pseudo-first order model with correlation factors of 0.999 and 0.950, respectively. Ce(III)-MAG held up to 790 bed volumes and the effluent fluoride concentration remained below 1.0 mg/L (influent fluoride 10 mg/L). (C) 2012 Elsevier Ltd. All rights reserved.