Maize Stalks as a Cheap Biosorbent for Removal of Fe (II) from Aqueous Solution

The evaluation of the ability of maize stalks to remove Fe(II) ions from aqueous solution was carried out. Different parameters affecting Fe(II) removal were investigated in batch experiments to optimize the removal method. These parameters include contact time, initial metal concentration, adsorbent dose, stirring rate, pH and temperature. Langmuir and Freundlich isotherm models were applied to the equilibrium data. The developed method showed high applicability to Langmuir isotherm model (R2=0.9806) compared with Freuindlich model (R2=0.8293) for the adsorption of Fe(II) on maize stalks. Maximum saturated monolayer sorption capacity of maize stalks for Fe(II) was 5.14 mg/g. Adsorption process was performed at different temperatures to evaluate the thermodynamic parameters. The negative ΔGo values at various temperatures confirms that biosorption processes is spontaneous. The adsorption process was endothermic (∆Ho = 6.174 KJ/mol) and the randomness at the adsorbent/solution interface increases during the sorption process (∆So = 22.622 J/mol k). The removal efficiency is a maximum at slightly acidic media. The proposed method could be applicable for removal of low concentrations of Fe(II) ions from aqueous solutions.