Optimization of humic acid removal by adsorption onto bentonite and montmorillonite nanoparticles

The results of this study showed that the nanoparticles examined were proven most effective in removing humic acid from aqueous solutions at pH = 3. Adsorption capacity increased by increasing the humic acid concentrations so adsorption capacity of bentonite and montmorillonite nanoparticles at humic acid concentration of 40 mg/L, reached to 58.21 and 48.20 mg/g, respectively. The results showed that adsorption process follows the Freundlich isotherm as well as pseudo-second order kinetics. The results of temperature and thermodynamic process showed that ΔS° values were positive for both absorbents and ΔH° values were negative, but the values of ΔG° became more negative with temperature decrease. The results lead to the conclusion that nanoclays are appropriate adsorbents for removing humic acid from aqueous solutions.