Humic acid adsorption onto Mg/Fe layered double hydroxide

Layered double hydroxides (LDHs) with Mg2+ and Fe3+ cations and having chloride or carbonate ions in the interlayer region have been prepared and characterized by different methods. The diameter of the prepared particle was in the range of 0.4–0.6 μm. The adsorption of humic acid onto chloride and carbonate intercalated LDHs with Mg/Fe (ratio = 4:1) was studied by adsorption isotherms at different ionic strengths. The adsorption of humic acid onto LDHs occurred by ion exchange with both the intercalated and surface anions of the LDH and ligand exchange reactions with surface groups. The contribution of both mechanisms to the total HA adsorption was estimated.