Adsorption behavior and mechanism of Sudan I by eggshell membrane.

Adsorption of Sudan I by the eggshell membrane was investigated with respect to various parameters such as p H, amount of adsorbent and ionic strength. The Results showed that the best adsorption capacity was found at 10 g·L-1eggshell membrane, p H6, 1% Na Cl.The adsorption equilibrium time was 140 min and the adsorbing capacity was 1.25 mg·g-1.Models of Langmuir, Freundlich and Temkin were used to fit the adsorption isotherms, all of the three models provided good fitting to the adsorption process ( R2 was 0.86~0.99) , but Freundlich model showed relatively better correlation coefficient ( R2> 0.97) . The adsorption thermodynamic parameters showed that Gibbs free energy ( ΔG) < 0, enthalpy ( ΔH) > 0, and entropy ( ΔS) > 0, indicating that the adsorption of Sudan I occured on heterogeneous sites with non-uniform distribution of energy levels and the adsorption process was spontaneous, endothermic and entropy increasing.On the other hands, Kinetics of the sorption process were also investigated and the adsorption kinetic process provided good fitting with the Lagergren pseudo-second order kinetic model.In conclusion, eggshell membrane have a good adsorption effect to Sudan I.