Magnetite modified with amine polymer to adsorb indium ions

Indium is one of the contaminants of the optoelectronics industry, and adsorption is a potential treatment method for this pollutant. A magnetic adsorbent manufactured from magnetite (Fe₃O₄) can be easily recovered from treated water by magnetic force without requiring further downstream treatment. In this research, the surface of magnetite is modified with oleic acid, methyl methacrylate and ethylenediamine (EDA/MMA/OA/Fe₃O₄). A magnetic adsorbent (EDA/MMA/OA/Fe₃O₄) made by magnetite modified with oleic acid, methyl methacrylate and ethylenediamine was used to adsorb indium ions solution in a batch system. The indium ions adsorption behavior by EDA/MMA/OA/Fe₃O₄ was in good agreement with both the Langmuir and Freundlich adsorption isotherm. The maximum adsorption capacity (q_m) and Gibbs free energy of indium ions at 298K was 54.18mgg^-1 and -17.94kJmol^-1, respectively. A pseudo-second-order model could best describe the adsorption kinetics, and the derived activation energy was 5.96kJmol^-1. The optimal condition of indium ions desorption from EDA/MMA/OA/Fe₃O₄ was provided by 0.01M HNO₃ in aqueous solution.