Chitosan-Fe-Al-Mn metal oxyhydroxides composite as highly efficient fluoride scavenger for aqueous medium

Nano-particles are highly efficient fluoride adsorbents, but agglomerate easily due to their high surface activity and are difficult to separate from aqueous medium after use. Mixed-metals oxyhydroxides nano-particles were prepared into a natural polymeric matrix of chitosan to overcome these problems. Hydrous mixed-metal oxyhydroxides, loaded chitosan composite ([email protected]) was prepared using abundantly available laterite clay and waste from steel industry via co-precipitation method. Fluoride removal using [email protected] composite followed Freundlich isotherm model which revealed multilayer adsorption on heterogeneous surface sites. [email protected] exhibited maximum adsorption capacity of 40±0.5 mg/g, while if only the inorganic mass fraction of composite was considered; the value reached 55±0.5 mg/g. Fluoride adsorption on [email protected] followed the pseudo-second order kinetics with rapid adsorption. No significant effect of other competitive ions was observed on F− adsorption using [email protected] composite. The composite adsorbent is found to be effective to produce drinking water from fluoride contaminated groundwater.