Facile Flow-Through Synthesis Method for Production of Large Quantities of Polyvinylpyrrolidone-Coated Magnetic Iron Oxide Nanoparticles for Oil Remediation

A novel continuous flow-through (FT) synthesis technique, which converted the hydrothermal synthesis conditions used in a previously reported batch process, was developed to produce polyvinylpyrrolidone-coated iron oxide nanoparticles (NPs). NPs have been shown to work for oil remediation in environmental systems, but a scaled-up synthesis is required for practical applications. The synthesis technique requires low temperatures and ambient pressure and does not use any inert gases and organic solvents. The method has potential to be developed into a massively parallel process for large-scale production. The as-synthesized iron oxide NPs were tested and compared with NPs produced from a previously developed batch method in terms of chemical and structural properties and their potential oil removal from aqueous samples relevant to the environment. Analysis showed that NPs produced from FT synthesis largely maintained their structural properties, although both core and hydrodynamic size of the NPs were slightly larger than those from the batch method, potentially affecting specific surface area and their ability to remove oil from aqueous solutions under challenging conditions. Nevertheless, results from experiments quantifying oil removal from water in synthetic seawater, with or without added fulvic acid or alginic acid, indicated that NPs synthesized from the FT technique showed excellent oil removal capacity (essentially 100% removal). Their oil removal efficiency was comparable to efficiency of the NPs synthesized from batch method.