Figure 2

(a) FT-IR spectra of Fe3O4, Fe3O4@PDA, and AgNPs-Fe3O4@PDA. (b) X-ray diffraction patterns of Fe3O4, Fe3O4@PDA, and AgNPs-Fe3O4@PDA. (c) TGA data of Fe3O4, Fe3O4@PDA, and AgNPs-Fe3O4@PDA. (d) Magnetic curves of Fe3O4, Fe3O4@PDA, and AgNPs-Fe3O4@PDA, inset photographs: separation of Fe3O4@PDA (upper left) and AgNPs-Fe3O4@PDA (lower right) from aqueous solution by using an external magnet.