Preparation and characterization of magnetically active polymeric particles (MAPPs) for complex environmental separations

Magnetic separation technique has the potential to achieve environmental se paration by selectively removing target toxic compounds from the background of complex matrices such as sludge, sediment, viscous or radioactive liqui d, biomass slurry, and others. A host of commercially available and/or tail ored 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 exper imental protocol to transform nonmagnetic polymeric particles into super pa ramagnetic ones by dispersing submicron magnetite crystals within the polym er phase. Careful control of redox conditions and use of elevated temperatu re help favor formation of magnetite crystals within the polymer phase whic h are independently identified through X-ray diffraction. Magnetically acti ve 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 processe s) of polymeric materials are not influenced by the presence of magnetite i n the polymer phase. Also, the acquired magnetic activity measured as speci fic magnetic susceptibility (chi(m)) is retained over multiple sorption-des orption cycles. Although every type of polymeric sorbent included in the st udy attained significant chi(m) values, sulfonic acid functional groups pro vide more favorable microenvironment for enhanced magnetic activity. Thus, partial functionalization of other polymeric sorbents with sulfonic acid gr oups is expected to offer improved performance for the proposed magnetic se paration technique.