Potent and Versatile Biogenically Synthesized Alumina/Nickel Oxide Nanocomposite Adsorbent for Defluoridation of Drinking Water.

In the present work, an extract of Salvia officinalis leaves was used to synthesize an alumina/NiO nanocomposite by the coprecipitation method. First, the shape and surface content of the synthesized adsorbent were determined. Scanning electron microscopy images showed the production of nanospheres and nanorods with sizes between 35 and 50 nm. X-ray diffraction measurement revealed strong, high-intensity peaks, confirming the preparation of a highly crystalline alumina/nickel oxide nanocomposite. Then, the pure nanoalumina, nickel oxide, and functionalized alumina/nickel oxide nanocomposite for water defluoridation were investigated under various conditions, for example, stirring period, pH, and initial fluoride concentration. Defluoridation with greener alumina, nickel oxide, and alumina/nickel oxide nanocomposite lasted 120 min at adsorbent dosages of 0.8 g/L in a pH 7 solution. The adoption process for the three sorbents matches the Langmuir adsorption isotherm. The process dynamics were explored using pseudo-second-order and first-order kinetics. The water quality after treatment met drinking water requirements, proving the viability of using nanoparticles for drinking water defluoridation. This work confirmed effective water defluoridation in the crystalline phase using synthesized nanoalumina, nickel oxide, and their nanocomposite, which highlights their importance for future drinking water defluoridation.