Optimisation of Defluoridation of Water by Zirconia Nanoparticles Using RSM

Abstract

In the present work, zirconia nanoparticles were investigated for the adsorption of fluoride from water. The effect of the factor variables viz., the effect of initial fluoride concentration, adsorbent dosage, pH, and contact time and their interactions on adsorption of fluoride ion were investigated by response surface methodology (RSM) based on central composite design (CCD). The maximum fluoride removal was around 95% at 7 pH, initial fluoride concentration of 10 ppm, adsorbent dosage of 12.5 g/L, and contact time at 105 min. To understand the adsorption mechanism of fluoride on to the nanoparticles, adsorption isotherms and adsorption kinetics were studied. The Langmuir isotherm adsorption model and pseudo-second-order kinetics model fitted well for the fluoride removal using zirconia nanoparticles. The nanoparticles were characterised before and after for their adsorption using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and SEM analysis.