Controllable Synthesis Of Magnetic Core-shell Nanocomposites And Their Performance For Water Purification

Magnetic nanomaterials have attracted considerable interest due to their potentialapplications in iatrology, heterogeneous catalysis, and water purifcation. In particular,core–shell nanocomposites containing both magnetic and active components haveshown improved properties and important technological applications because of theirmagnetic properties and variable surface properties. In this study, magnetic core-shellnanocomposites were synthesized for water treatment, and the synthetic mechanismwas discussed. The adsorption capability and catalytic activity of the synthesizedcore-shell nanocomposites, including Fe3O4and MnFe2O4, were studied.The main research contents and results are listed as follow.(1) Synthesis of magnetic core-shell nanocomposites using Fe3O4as the core andtheir adsorption capabilityFe3O4was prepared by an ultrasound coprecipitation method. The shell materialwas synthesized by a reaction between Mn2+/Co2+and MnO4-, and its composition andstructure can be modified through manipulation of precursor adsorption, and thesynthesis mechanism was discussed. The magnetic core-shell nanocomposite FCMexhibits excellent adsorption capability for Pb(II), Cu(II) and Cd(II) and methyleneblue.(2) Synthesis of magnetic core-shell nanocomposites using MnFe2O4as the coreand their adsorption capabilityThe magnetic core-shell nanocomposites were synthesized using MnFe2O4, andtheir adsorption properties toward heavy metals were investigated. The results showedthat magnetic core-shell nanocomposites MCM have highly negatively chargedsurface and good dispersion in aqueous solution. The adsorption properties of MCMtoward heavy metals was obviously superior to FCM. MCM exhibit excellentperformance for heavy metals removal over a wide pH range, and the maximaladsorption capacities for Pb(II), Cu(II) and Cd(II) are481.2,386.2and345.5mg g1,respectively. All the metal ions in mixed solution can be completely removed in ashort time. Morever, the adsorbent exhibited excellent desorption property. (3) Catalytic ozonation of p-chlorophenol over magnetic core-shellnanocompositesThe catalytic activities of different magnetic core-shell nanocomposites for theozonation of p-chlorophenol in water were studied. The results showed that FCMexhibited the best catalytic activity, and the organic pollutants can be completelymineralized from aqueous solutions. Furthermore, the catalyst exhibited excellentstability. Finally, the catalytic ozonation mechanism was discussed. Ozone wasadsorbed on the surface of the catalyst, and subsequently decomposed into hydroxylradical (·OH). Hydroxyl radical is the main active species in this catalytic reaction.