Hydrothermal synthesis of LaFeO nanoparticles adsorbent: Characterization and application of error functions for adsorption of fluoride.

The adsorption of fluoride from aqueous solution by lanthanum ferrite nanoparticles (LaFeO NPs) synthesized by the hydrothermal method has been investigated. This experimental study was conducted on a laboratory scale. The effects of various operating parameters such as pH (3-11), LaFeO NPs dosage (0.1-1.0 g/L), contact time (15-120 min), temperature (303-318 K), and initial concentration of fluoride (15-40 mg/L) on fluoride adsorption were studied. The results showed that under optimal conditions of fluoride concentration of 20 mg/L, pH of 5, LaFeO NPs dosage of 0.9 g/L, temperature of 308 K, and contact time of 60 min, maximum percentage removal of 94.75 % was obtained. The process of fluoride adsorption on LaFeO NPs was found to depend on the Freundlich adsorption and Koble-Corrigan isotherm models. The monolayer adsorption capacity of LaFeO NPs was 2.575 mg/g. The kinetic data fitted best into the pseudo-second-order model considering the values of the regression coefficients (r) and error functions used. The thermodynamics study indicated that the adsorption process was exothermic (Δ°< 0) and spontaneous (ΔG°< 0) in nature. It could be concluded that the synthesized LaFeONPs can be used as an effective adsorbent for fluoride ions removal from aqueous solutions.