Efficient removal of trace antimony(III) through adsorption by hematite modified magnetic nanoparticles.

Hematite coated magnetic nanoparticle (MNP@hematite) was fabricated through heterogeneous nucleation technique and used to remove trace Sb(III) from water. Powder X-ray diffraction, transmission electron microscopy (TEM), and alternating gradient magnetometry were utilized to characterize the prepared adsorbent. TEM image showed that MNP@hematite particles were spherical with size of 10-30nm. With saturation magnetization of 27.0emu/g, MNP@hematite particles could be easily separated from water with a simple magnetic process in short time (5min). At initial concentration of 110μg/L, Sb(III) was rapidly decreased to below 5μg/L by MNP@hematite in 10min. Sb(III) adsorption capacity of MNP@hematite was 36.7mg/g, which was almost twice that of commercial Fe3O4 nanoparticles. The removal of trace Sb(III) was not obviously affected by solution pH (over a wide range from 3 to 11), ionic strength (up to 100mM), coexisting anions (chloride, nitrate, sulfate, carbonate, silicate, and phosphate, up to 10mM) and natural organic matters (humic acid and alginate, up to 8mg/L as TOC). Moreover, MNP@hematite particles were able to remove Sb(III) and As(III) simultaneously. Trace Sb(III) could also be effectively removed from real tap water by MNP@hematite. The magnetic adsorbent could be recycled and used repeatedly.