Abstract
Organo-manganese dioxide (MnO(2)) thin films intercalated with cetyltrimethylammonium chloride (CTAC/MnO(2)) were successfully fabricated via electrochemical deposition and applied for selective iodide (I(-)) recovery from aqueous solutions. The CTAC/MnO(2) thin films exhibited high sorption capacities for I(-), following Langmuir-type monolayer sorption behavior with a maximum sorption capacity of 211 mg g(-1). X-ray photoelectron spectroscopy revealed that iodide sorption proceeded primarily via anion exchange with interlayer Cl(-), without redox transformation of Mn species. Solvent extraction studies confirmed a 1:1 stoichiometry between CTA(+) and I(-) during complex formation. Iodide was electrochemically desorbed under cathodic polarization and resorbed after anodic polarization, demonstrating the reusability of the material. Competitive sorption experiments demonstrated that CTAC/MnO(2) thin films maintained excellent selectivity for I(-) even in the presence of excess chloride and sulfate ions, attributed to differences in dehydration energy and structural compatibility within the hydrophobic interlayer space. Furthermore, CTAC/MnO(2) thin films successfully recovered I(-) from modified artificial seawater devoid of Ca(2+) and HCO(3)(-), thus highlighting the practical feasibility of this system in the absence of key interfering ions. Additionally, a D2EHPA-based solvent extraction pretreatment was developed to selectively remove Ca(2+) and HCO(3)(-) from saline solutions.