Ag NPs decorated on the magnetic Fe3O4@PDA as efficient catalyst for organic pollutants removal and as effective antimicrobial agent for microbial inhibition

In this paper, Ag NPs-decorated magnetic Fe3O4 @PDA nanocomposites have been successfully prepared. The spherical Fe3O4 nanoparticles with an average size approximately 340 nm were modified by dopamine under mild conditions. Dopamine was self-polymerized surrounding Fe3O4 nanoparticles and transformed into poly dopamine (PDA) layers. The PDA-encapsulated magnetic (Fe3O4 @PDA) nanoparticles could in-situ reduce silver ammonium ions by the catechol groups in PDA layers. The Ag NPs with an average size ranging from 20 nm to 36 nm were densely decorated on the thin PDA shell. The resultant Fe3O4 @PDA-Ag nanocomposites were employed as highly efficient catalysts for the reduction of different organic pollutants in the appearance of sodium borohydride. The Fe3O4 @PDA-Ag nanocomposites also demonstrated extraordinary cycling stability when the catalyst was recycled several times for the reduction of MB. The antimicrobial tests indicated Fe3O4 @PDA-Ag nanocomposites could efficiently prohibit the growth of microorganism, including various bacteria and fungi. The minimal inhibitory concentrations (MIC) for Fe3O4 @PDA-Ag nanocomposites against different bacteria and fungi were also determined. The excellent catalytic activity, magnetic recyclability, and antimicrobial performance make Fe3O4@PDA-Ag a feasible candidate for the remediation of wastewater which contains multiple water soluble organic pollutants and pathogenic microorganism.