Abstract
In the present study, defluoridation study of liquid phase with the help of multi-walled carbon nanotubes (MWCNTs) and single-walled carbon nanotubes (SWCNTs) were well investigated and elucidated. The impact of different experimental conditions such as solution pH, initial fluoride concentration, adsorbent dose, and contact time was well studied and optimized for the maximum fluoride removal from water. The experimental data were fitted by the Freundlich, Langmuir and Dubinin–Radushkevich (D–R) isotherm models and the related equilibrium constants were calculated. The results of the isotherm studies showed that fluoride removal by both adsorbents followed the Freundlich isotherm model. Kinetic studies were conducted and the results demonstrated that the experimental data were fitted well with the pseudo-second order kinetic model. Furthermore, two multiple regression-based equations were also derived to model the removal of fluoride from aqueous solutions by the carbon nanotubes. This study demonstrated that the polynomial equations satisfactorily described the behavior of the present defluoridation process for both MWCNTs (R2=0.913) and SWCNTs (R2=0.941).
Surface textural and morphological presentation of the used adsorbents [Display omitted]
•MWCNTs and SWCNTs were used as adsorbent for the removal of fluoride.•The optimized contact time and pH were found to be 30min and 5 respectively.•Fluoride removal decreases with the increase in solution pH.•The percentage removal efficiency decreased with increased in fluoride concentration.•The optimized adsorbent dose for the process is 0.5g/L.