Silver nanoparticles decorated magnetic polymer composites (Fe3O4@PS@Ag) as highly efficient reusable catalyst for the degradation of 4-nitrophenol and organic dyes.

A facile and cost-effective preparation of silver nanoparticles decorated magnetic composite for the effective catalytic degradation of 4-nitrophenol (4-NP) and Methylene blue (MB) and Rhodamine B (RhB) was investigated. Fe3O4@Polystyrene@Ag (Fe3O4@PS@Ag) catalyst was prepared via a two-step procedure. Firstly, carboxyl groups modified magnetic microspheres (Fe3O4@PS-COOH) has been successfully synthesized by microemulsion polymerization. Then Ag ions were adsorbed and in-situ reduced on the surface of Fe3O4@PS microspheres. To estimate the catalytic activity of Fe3O4@PS@Ag catalyst, the reduction experiments of MB, RhB and 4-NP were performed in the presence of NaBH4. The results indicated that Fe3O4@PS@Ag catalyst has a good catalytic performance and these dyes can be reduced in a very short time, which the apparent rate coefficients are 0.0089 s-1, 0.0187 s-1 and 0.0086 s-1 for MB, RhB and 4-NP respectively. In addition, it could be easily collected from aqueous solution by a magnet so that the catalyst could be recovered and reused after the catalytic process. The catalytic activity was still high after seven cycles. This catalytic reaction is in agreement with the pseudo-first-order kinetic equation. Furthermore, the as-prepared Fe3O4@PS@Ag catalyst outperforms other catalysts in the degradation of these organic dyes.