Development of hyperbranched polymer encapsulated magnetic adsorbent (Fe3O4@SiO2-NH2-PAA) and its application for decontamination of heavy metal ions

The water dispersible magnetic adsorbent was fabricated by functionalization of magnetic nanoparticles (MNPs) with 3-aminopropyl trimethoxysilane (APTMS) and dendrimer-like polyamidoamine; the sorbent is named as Fe3O4@SiO2-NH2-PAA. The amine rich Fe3O4@SiO2-NH2-PAA adsorbent was further used in retrieval of heavy metal ions such as Cd(II), Co(II), Zn(II), Pb(II) and Cu(II) from the aqueous medium. Fabrication of Fe3O4@SiO2-NH2-PAA involves a two-step process: (i) surface initiation of MNPs by ligand exchange reaction and condensation of APTMS (Fe3O4@SiO2-NH2),(ii) surface functionalization of MNPs by controlled/living polymerization. Surface functional groups, crystallization characteristics, surface morphologies and magnetic properties of the adsorbent were analyzed by FT-IR, XRD, SEM, TEM, and VSM. The characterization outcomes showed that functionalization improved the oxygen and nitrogen atomic percentages of adsorbent resulting enriched adsorption. Sorption isotherm and kinetic models illustrated that sorption data better fitted to Langmuir isotherm model and pseudo-second order kinetic model. These results suggest that sorption process is monolayer and is chemical in nature. The order of sorption capacities (mg g(-1)) based on Langmuir isotherm model are: Pb(II) (108.82) > Cd(II) (100.81) > Co(II) (95.40) > Zn(II) (89.62)> Cu(II)(87.82). These findings suggest that as developed magnetic sorbent can be replaceable for traditional adsorbents due its high sorption performance, rapid kinetics, and magnetic separation characteristics.