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

Here we describe the integration of spherical and rod-liked Fe0/iron oxides nanoparticles into polyvinylidene fluoride (PVDF) polymeric microcapsule via phase inversion technique. This synthesis technique allows the encapsulation of Fe0/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 interaction, and the colloidal stability of the particles before its encapsulation into the polymeric network. Both nanorod-PVDF and nanosphere-PVDF microcapsules retained their magnetic properties after MB removal and can be magnetophoretically collected in real time by a permanent NdFeB magnet with surface magnetic field at approximately 5500 gauss.

Magnetic nanoparticle augmented polymeric microcapsule with magnetic and catalytic bifunctionalities can be employed for decolorization of methylene blue.Figure optionsDownload as PowerPoint slideHighlights
► Synthesis of nanoparticles–polymeric microcapsule by phase inversion technique.
► Hybrid materials with catalytic and magnetic properties.
► The as synthesized microcapsule achieved high methylene blue loading at 80 mg/g.
► After recycled for five times the microcapsule still retained >90% initial efficiency.
► Colloid stability and electrostatic interaction contributions were investigated.