Magnetic Activated-ATP@Fe3O4 Nanocomposite as an Efficient Fenton-Like Heterogeneous Catalyst for Degradation of Ethidium Bromide

Magnetic attapulgite-Fe 3 O 4 nanocomposites (ATP-Fe 3 O 4 ) were prepared by coprecipitation of Fe 3 O 4 on ATP. The composites were characterized by scanning electron microscopey, X-ray diffractometry, Brunauer-Emmett-Teller analysis, X-ray photoelectron spectroscopy, energy dispersive spectrometer and transmission electron microscopy. Surface characterization showed that Fe 3 O 4 particles with an average size of approximately 15 nm were successfully embedded in matrix of ATP. The capacity of the Fe 3 O 4 -activated ATP (A-ATP@Fe 3 O 4 ) composites for catalytic degradation of ethidium bromide (EtBr, 80 mg/L) at different pH values, hydrogen peroxide (H 2 O 2 ) concentrations, temperatures, and catalyst dosages was investigated. EtBr degradation kinetics studies indicated that the pseudo-first-order kinetic constant was 2.445 min −1 at T  = 323 K and pH 2.0 with 30 mM H 2 O 2 , and 1.5 g/L of A-ATP@Fe 3 O 4 . Moreover, a regeneration study suggested that A-ATP@Fe 3 O 4 maintained over 80% of its maximal EtBr degradation ability after five successive cycles. The effects of the iron concentrations and free radical scavengers on EtBr degradation were studied to reveal possible catalytic mechanisms of the A-ATP@Fe 3 O 4 nanocomposites. Electron Paramagnetic Resonance revealed both hydroxyl (∙OH) and superoxide anion (∙O 2 − ) radicals were involved in EtBr degradation. Radical scavenging experiment suggested EtBr degradation was mainly ascribed to ∙OH radicals, which was generated by reaction between Fe 2+ and H 2 O 2 on the surface of A-ATP@Fe 3 O 4 .