Fluoride adsorption on hydroxyapatite: From batch to continuous operation

In the present paper, the removal of fluoride from drinking was investigated via adsorption technique, an important contaminant that could cause serious threat to human health. The challenge of this work is the scaleup from batch to continuous operation, including regeneration of the adsorbent, using a commercial hydroxyapatite, namely Fuorandel (R). Adsorption Dynamic Intraparticle Model (ADIM) was used to describe the data collected in batch mode, obtaining important parameters to design a continuous adsorption column, such as: surface diffusivity, DS, and tortuosity, tau. Those parameters were fixed to simulate the experimental data collected in a continuous device obtaining good results. Finally, the sorbent regeneration in a batch system was investigated, optimizing the conditions to enhance Fluorandel (R) recovery. The present paper shows clearly the potential application of the selected sorbent, giving all the tools needed to scale-up the operation at industrial level.