Granulation of Fe–Al–Ce nano-adsorbent for fluoride removal from drinking water by spray coating on sand in a fluidized bed

A technology for the granulation of Fe–Al–Ce nano-adsorbent (Fe–Al–Ce) in a fluidized bed was developed. The coating reagent, a mixture of Fe–Al–Ce and a polymer latex, was sprayed onto sand in a fluidized bed. The granule morphology, coating layer thickness, granule stability in water and adsorption capacity for fluoride was investigated by analyzing samples for different coating time. The coating amount was from 3% to 36%. With increasing coating amount, granule stability decreased and adsorption capacity increased. FTIR analysis showed that the latex can react with active hydroxyl on the Fe–Al–Ce adsorbent, which led to a decrease of the adsorption capacity. Coated granules with a coating amount of 27.5% had a fluoride adsorption capacity of 2.22 mg/g (coated granules) at pH 7 and initial fluoride concentration of 0.001 M. A column test showed that 300 bed volumes can be treated with the effluent under 1.0 mg/L at an initial fluoride concentration of 5.5 mg/L, space velocity of 5 h− 1 and pH of 5.8. The coating granulation of the Fe–Al–Ce adsorbent can produce granules that can be used in a packed bed for the removal of fluoride from drinking water.

Graphical AbstractA technology for the granulation of Fe–Al–Ce nano-adsorbent by spray coating on sand with an acrylic-styrene copolymer latex as a binder in a fluidized bed was developed. The effects of coating amount on adsorption capacity and the stability of the granules were investigated. Using the coated granules as adsorbent, high stability and fluoride adsorption capacity was achieved.Figure optionsDownload as PowerPoint slide