Sulfonate group is the most common ligand used for purifying lactoferrin. The isotherm adsorption curves of lactoferrin on three adsorbents with sulfonic ligand at different pHs and salt concentrations showed that adsorption capacity decreased with the increase of pH or salt concentration. Further molecular simulation was performed to compare the electrostatic potential of lactoferrin under different conditions. It could be presumed that the mechanism of pH effect was the change of protonation of amino acid residues on the surface of protein and the change of electrostatic potential consequently

while the mechanism of salt effect could be the shield of electrostatic interaction between protein and ligand with no impact on electrostatic potential distribution obviously. Finally

the binding energy between protein and ligand under different conditions was calculated to quantify adsorption capacity and characterize the effects of pH and salt concentration.