Influence of dissolved oxygen on Fe(II) and Fe(III) sorption onto chitosan

• Of all the iron ions only Fe(III) are sorbed by chitosan. Fe(II) removal from solutions proceeds after its oxidation to Fe(III).
• The dissolved oxygen and increasing values of pH favour the conversion of Fe(II) ions into Fe(III).
• Iron ion removal from solutions proceeds due to the formation of bonds between the –OH groups of chitosan and Fe(III) ions.

The Fe(II) and Fe(III) ions uptake by chitosan is distinguished by rapid sorption kinetics in comparison with that of other heavy metals such as Cu(II) and Ni(II).The correlation between the kinetics of dissolved oxygen and Fe(II) ions sorption by chitosan points to the different sorption mechanisms for Fe(II) and Fe(III). The consumption of dissolved oxygen corresponds to the sorbed Fe(II) quantities indicating its conversion to Fe(III). Only Fe(III) is sorbed by chitosan. The sorption proceeds by the interaction of these ions with –OH groups of chitosan.

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