Design and synthesis of magnetic nanoparticles augmented microcapsule with catalytic and magnetic bifunctionalities for dye removal

摘要

Here we describe the integration of spherical and rod-liked Fe°/iron oxides nanoparticles into polyvinylidene fluoride (PVDF) polymeric microcapsule via phase inversion technique. This synthesis technique allows the encapsulation of Fe°/iron oxides nanoparticles, with both magnetic and catalytic properties, into PVDF polymeric microcapsule which further enhances its pollutant removal efficiency through two mechanisms: entrapment by polymeric network, follow with catalytic degradation by nanoparticles. A model system by using methylene blue (MB) as targeted pollutant was employed to test the feasibility of this idea. By having the magnetic nanoparticles within the PVDF microcapsule has at least boost the capability to remove MB by a factor of three compared to freely suspended nanoparticles and recorded a removal efficiency of ~80 mg/g-microcapsule. After subjected to five cycles of MB removal, the nanoparticle augmented microcapsules are still retaining more than ~90% of their initial performance while the PVDF-only microcapsule loses its MB removal capability after the first cycle. The successful surface functionalization of magnetic nanoparticles was characterized by dynamic light scattering (DLS) and electrophoretic mobility measurement The effects of surface functionalization of magnetic nanoparticles on the MB removal are interpreted in terms of the particle-pollutant electrostatic interactioa and the colloidal stability of the particles before its encapsulation into the polymeric network. Both nano-rod-PVDF and nanosphere-PVDF microcapsules retained their magnetic properties after MB removal and can be magne-tophoretically collected in real time by a permanent NdFeB magnet with surface magnetic field at approximately 5500 gauss.