Agglomerated nanoparticles of hydrous Ce(IV)+Zr(IV) mixed oxide: Preparation, characterization and physicochemical aspects on fluoride adsorption

Rapid and efficient removal of fluoride ions from aqueous solution using a polypyrrole coated hydrous tin oxide nanocomposite

“…The trend of q e values obtained from the linear fit of pseudo-second-order model showed an increase with an increase in concentration; this can be accredited to the fact that adsorption being a passive process, is specifically driven by concentration gradient as a driving force [12]. Furthermore, pseudo-second-order rate constant k 2 decreases from (0.691 ± 0.049) to (0.077 ± 0.015) g/mg/min with an increase in initial concentration that is due to the faster F À adsorption from the dilute solution than the concentrated one, which is similar to the results reported by other workers [35]. All these results confirmed that the F À sorption kinetics can be better described by the pseudo-second-order model.…”

“…The non-linear [35] and linear [30] forms of Langmuir isotherm are given by Eqs. (12) and (13) respectively:…”

“…The non-linear [35] and linear [30] forms of Freundlich isotherm expressed by Eqs. (15) and (16) respectively were also applied to isotherm data to evaluate its applicability: …”

β-Cyclodextrin modified hydrous zirconium oxide: Synthesis, characterization and defluoridation performance from aqueous solution

“…Alternatively, negatively charged over the surfaces of CY-HZO (pH pzc = 5.5) exerts more repulsion at pH 7.0 on fluoride ions than HZO (pH pzc = 6.5) and the decrease of adsorption rate over HZO is insignificant. including the modelling of data by the isotherms equations (SI section) [46,47] such as Langmuir (Eq. S3) and Freundlich (Eq.…”

“…S6shows the percentages of fluoride adsorption over CY-HZO versus the solution pH, which showed the escalation of adsorption percentages with increasing pH upto ~5.0, and then reduced[46,47]. At lower pH, especiallybelow the pH PZC of CY-HZO (5.5), the positive charge (E1) over the solid surface accelerates the solution fluoride ions adhered to the surface owing to Columbic forces which explains the upward trend of adsorption capacity (q e ) / adsorption percentage.…”