Degradation of sulfamonomethoxine with Fe3O4 magnetic nanoparticles as heterogeneous activator of persulfate.

Iron oxide magnetic nanoparticles (Fe(3)O(4) MNPs) can effectively activate persulfate anions (S(2)O(8)(2-)) to produce sulfate free radicals (SO(4)(-)), which are a powerful oxidant with promising applications to degrade organic contaminants. The kinetics of sulfamonomethoxine (SMM) degradation was studied in the system of Fe(3)O(4) MNPs and S(2)O(8)(2-). A complete removal of the added SMM (0.06 mmol L(-1)) was achieved within 15 min with the addition of 1.20 mmol L(-1) S(2)O(8)(2-) and 2.40 mmol L(-1) Fe(3)O(4) MNPs. There is an optimum concentration of Fe(3)O(4) MNPs because Fe(3)O(4) MNPs may also act as a SO(4)(-) scavenger at higher concentrations. It was further observed that the addition of Fe(3)O(4) MNPs in several batches for a given total amount of the activator is favorable to enhancing the degradation of SMM. A degradation mechanism was proposed on the basis of identification of the degradation intermediates of SMM with liquid chromatography combined with mass spectroscopy.