Optimization of a Fe–Al–Ce nano-adsorbent granulation process that used spray coating in a fluidized bed for fluoride removal from drinking water

A coating granulation technology comprising the spraying of a Fe–Al–Ce nano-adsorbent suspension onto glass beads in a fluidized bed was developed. An acrylic-styrene copolymer latex was used as a binder. The granulated adsorbent was used in a packed bed for fluoride removal from drinking water. The effects of coating temperature, latex/Fe–Al–Ce ratio, and coating amount on granule compressive strength and adsorption capacity were investigated. With increased coating temperature, cross linking in the polymer in the coated layer increased, which resulted in increased granule strength but decreased adsorption capacity. With increased latex/Fe–Al–Ce ratio, more active sites were covered by the polymer, which also resulted in increased granule strength but decreased adsorption capacity. The optimal parameters for making high performance adsorbent granules were for the granules to be coated at 65 °C using a latex/Fe–Al–Ce ratio of 0.5:1 and a coating amount of 27.8%. These granules had a fluoride adsorption capacity of 2.77 mg/g (coated granules) for water with an initial fluoride concentration of 0.001 M that was treated at pH 7.

Graphical AbstractThe parameters for the granulation by spraying of a Fe–Al–Ce nano-adsorbent suspension onto glass beads in a fluidized bed were optimized. The granules having a suitable fluoride adsorption capacity and compressive strength were obtained, which can be used as a filter in a packed bed for fluoride removal from drinking water.Figure optionsDownload as PowerPoint slide