Gold-Nanoparticle Decorated Monosized Magnetic Polymer Based Catalyst: Reduction of 4-Nitrophenol

Abstract

The objective of this study was to fabricate a multifunctional catalyst for removal of environmental pollutants. By this aim, poly(mono-2-(methacryloyloxy)ethyl succinate-co-glycerol dimethacrylate) “poly(MMES-co-GDMA)” monosized microbeads with carboxyl functionality were synthesized 5 µm in diameter. Iron oxide nanoparticles were attached onto the polymeric microbeads to obtain superparamagnetic properties for easily collecting them from the reaction medium by using natural magnet. The magnetic polymer microbeads were decorated with gold nanoparticles ca. 15 nm in size. The magnetic-monodisperse catalyst carrying gold nanoparticles exhibited several advantages with respect to similar plasmonic catalysts in the form of nanoparticles, like higher aggregation resistance, easier recovery from the reaction medium with natural magnets and reuse of catalyst without leaching gold nanoparticles. The magnetic gold catalyst was characterized by scanning electron microscopy (SEM), vibrating sample magnetometry (VSM) and X-ray diffraction spectrophotometry (XRD). This newly designed catalyst was used to degrade a toxic organic substance, 4-nitrophenol (4-NP) in an aqueous medium. The degradation process of 4-NP to 4-aminophenol (4-AP) was monitored by a UV–Visible spectrophotometer. The effects of reaction conditions, catalyst and organic pollutant concentrations and temperature, on the plasmonic catalytic activity were determined. The results of repetitive trials were successful with high catalytic activity for the reduction of 4-NP to 4-AP form in several minutes by using and reusing the synthesized catalyst.