Preparation and Characterization of Magnetically Active Polymeric Particles (MAPPs) for Complex Environmental Separations

Abstract

Magnetic separation technique has the potential to achieve environmental separation by selectively removing target toxic compounds from the background of complex matrices such as sludge, sediment, viscous or radioactive liquid, biomass slurry, and others. A host of commercially available and/or tailored polymeric sorbents exhibit specific affinities toward a wide array of dissolved environmental contaminants. They are, however, nonmagnetic. Thus, they do not respond to magnetic field. This study presents a refined experimental protocol to transform nonmagnetic polymeric particles into super paramagnetic ones by dispersing submicron magnetite crystals within the polymer phase. Careful control of redox conditions and use of elevated temperature help favor formation of magnetite crystals within the polymer phase which are independently identified through X-ray diffraction. Magnetically active polymeric particles (MAPPs), thus prepared, offer new opportunities for enhanced separation in complex environmental systems. Experimental results confirm that sorption properties (both equilibrium uptake and rate processes) of polymeric materials are not influenced by the presence of magnetite in the polymer phase. Also, the acquired magnetic activity measured as specific magnetic susceptibility (χm) is retained over multiple sorption−desorption cycles. Although every type of polymeric sorbent included in the study attained significant χm values, sulfonic acid functional groups provide more favorable microenvironment for enhanced magnetic activity. Thus, partial functionalization of other polymeric sorbents with sulfonic acid groups is expected to offer improved performance for the proposed magnetic separation technique.