Biomaterial functionalized cerium nanocomposite for removal of fluoride using central composite design optimization study.

Excess fluoride concentration in drinking water is a global issue, as this has an adverse effect on human health. Several adsorbents have been synthesized from natural raw material to remove fluoride from water. Reported adsorbents have some problems with the leaching of metal ions, fewer adsorption sites, and low adsorption capacity. Therefore, to address this, an effective biomaterial derived from the Luffa cylindrica (LC), containing many active sites, was integrated with a nano form of cerium oxide to form a robust, biocompatible, highly porous, and reusable LC-Ce adsorbent. This synthesized biosorbent offers better interaction between the active sites of LC-Ce and fluoride, resulting in higher adsorption capacity. Several factors, influence the adsorption process, were studied by a central composite design (CCD) model of statistical analysis. Langmuir's and Freundlich's models well describe the adsorption and kinetics governed by the pseudo-second-order model. The maximum monolayer adsorption capacity was found to be 212 and 52.63 mg/g for LC-Ce and LC, respectively determined by the Langmuir model. Detailed XPS and FTIR analyses revealed the underlying mechanism of fluoride adsorption via ion-exchange, electrostatic interaction, H-bonding, and ion-pair formation. All the results indicate that LC-Ce could serve as a suitable adsorbent for efficient fluoride removal (80-85%).