Selective fluoride adsorption by a hydrotalcite/chitosan composite

Hydrotalcite (HT) possesses an appreciable defluoridation capacity (DC). In order to enhance its DC and to make it into a usable form, a HT/chitosan (HTCs) composite was prepared which showed a DC of 1255 mg F−/kg compared to 1030 and 52 mg F−/kg for HT and chitosan respectively. Batch adsorption studies were carried out to evaluate the influence of contact time, pH, co-anions, initial fluoride concentration and temperature. The composite was characterized using FTIR, XRD and SEM with EDAX analysis. The equilibrium adsorption data was fitted with the Langmuir model. The reaction-based and diffusion-based models were used to identify the kinetics of the reaction. The suitability of the composite was tested at field conditions.