Oil-field wastewater purification by magnetic separation technique using a novel magnetic nanoparticle

► Novel magnetic seeds are applied in superconducting magnetic separation system. ► These magnetic seeds consist of magnetic core, dense and mesoporous silica layer. ► The plasma coating technique aids functionalizing the magnetic seeds with polymers. ► These magnetic seeds have appropriate magnetic and adsorptional properties. ► Experiments of purification of oil field wastewater show positive results.