Facile aqueous-phase synthesis of magnetic iron oxide nanoparticles to enhance the removal of iodine from water

The conventional synthesis of highly crystalline metal oxide nanoparticles requires either a reaction temperature of more than 300 °C or very high pressure, thus making their production economically infeasible. Here we report a simple aqueous-phase strategy for the synthesis of single-crystal metal oxide nanoparticles. Highly crystalline Fe₃O₄ and Mn₃O₄ nanoparticles were synthesized via the heating of an aqueous solution containing a metal precursor, branched polyethyleneimine (BPEI), and hexylamine at 95 °C for 3 h. The synthesized nanoparticles were characterized by a single crystal structure and good crystallinity. In this synthesis method, BPEI acts as the major capping agent for the formation of nano-sized particles and hexylamine acts as a weak base increasing the pH of the reaction solution, thus allowing the sol-gel reaction to form metal oxide nanoparticles. The synthesized Fe₃O₄ nanoparticles could be used as an efficient adsorbent for iodine removal from aqueous solutions using electrostatic attraction.