Fluoride Adsorption Comparison from Aqueous Solutions Using Al- and La-Modified Adsorbent Prepared from <i>Polygonum orientale</i> Linn.

Al- and La-modified adsorbent materials (PO–Al, PO–La) were prepared by impregnating Polygonum orientale Linn. straw with Al2(SO4)3 and La(NO3)3·6H2O solutions. The potential of removing fluoride using these modified adsorbents was examined. In the PO, PO–Al and PO–La adsorption systems, the fluoride adsorption process followed pseudo-second-order kinetics, and the kinetic constants for k2 and R2 were 0.0276 and 0.9609; 0.2070 and 0.9994; 0.1266 and 0.9933, respectively. The adsorption equilibrium results showed the best match with Langmuir isotherms. Moreover, the maximum monolayer adsorption capacity of PO, PO–Al and PO–La are 0.0923, 3.3190 and 1.2514 mg/g, respectively, in 30 °C. The regeneration results show that the effectively regenerating ability of modified adsorbents. Al-modified adsorbent showed the best results in terms of cost-effectiveness and adsorption efficiency for fluoride adsorption