Production and application of a treated bentonite–chitosan composite for the efficient removal of humic acid from aqueous solution

Humic acids have a significant undesirable influence on drinking water quality. In this study, we utilized a physically and chemically treated bentonite–chitosan composite (TBCH) for the removal of humic acid from aqueous solutions. Response surface methodology (RSM) using central composite design (CCD) was used to investigate the effects of pH, adsorbent dosage, humic acid concentration and contact time on the adsorption effectiveness of humic acid by TBCH. Isotherms, kinetics and thermodynamics have been also studied. An optimum condition for humic acid uptake was achieved at pH 4, 1.4 g/L adsorbent dosage, 40 mg/L humic acid concentration, and 115 min contact time. This study showed that modified bentonite and chitosan composite (TBCH) was a promising adsorbent for the removal of humic acid from aqueous solutions due to its significant removal efficiency, natural abundance and low cost; it may be an alternative to more costly available materials.