Polyethylenimine–Silica–Magnetic Nanoparticle Composites for Efficient Extraction of Dissolved Copper from Aqueous Solutions and Multiphase Mixtures

Design of micro/nanoadsorbents developed for effective copper extraction should consider methods of their retrieval from relevant copper-rich environments, which are commonly complex multiphase mixtures, such as slurries of polluted soils and sediments, copper minerals including low-grade ores, and industrial and mining wastes. This work reports integration of copper-chelating polyethylenimine (PEI) with a robust silica network and highly magnetic magnetite nanoparticles, resulting in magnetic PEI–silica nanocomposite microparticles that enable efficient binding of copper ions in both aqueous solutions and complex, multiphase mixtures with subsequent retrieval using magnetic force. Produced via simple emulsion templating, these nanocomposite particles can withstand highly acidic conditions and multiple copper extraction cycles, without loss of efficiency after five consecutive cycles of copper extraction. PEI–silica–magnetic nanoparticles composites effectively bind all copper ions leached into an aqueous phase and allow their rapid magnetically induced separation from aqueous solutions and mixtures of both coarse and fine solid particles, demonstrating promising results for progress toward more sustainable copper extraction techniques.