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

Shuwen Han,Tingting Yang,Shengsen Wang,Hemin Yu,Xiaozhi Wang

doi:10.1038/s41598-017-06398-3

Abstract

Magnetic attapulgite-Fe3O4 nanocomposites (ATP-Fe3O4) were prepared by coprecipitation of Fe3O4 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 Fe3O4 particles with an average size of approximately 15 nm were successfully embedded in matrix of ATP. The capacity of the Fe3O4-activated ATP (A-ATP@Fe3O4) composites for catalytic degradation of ethidium bromide (EtBr, 80 mg/L) at different pH values, hydrogen peroxide (H2O2) 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 H2O2, and 1.5 g/L of A-ATP@Fe3O4. Moreover, a regeneration study suggested that A-ATP@Fe3O4 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@Fe3O4 nanocomposites. Electron Paramagnetic Resonance revealed both hydroxyl (∙OH) and superoxide anion (∙O2−) radicals were involved in EtBr degradation. Radical scavenging experiment suggested EtBr degradation was mainly ascribed to ∙OH radicals, which was generated by reaction between Fe2+ and H2O2 on the surface of A-ATP@Fe3O4.

Highlights

Ethidium bromide (EtBr) is widely employed for rapid visualization of nucleic acids in electrophoretic gels and is commonly used in the life sciences[1]
The intensities of the ATP peak at 2θ = 19.8° and the quartz peaks at 2θ = 20.9° and 26.6° were weaker for the Fe3O4-purified ATP (P-ATP@Fe3O4) and Fe3O4-activated ATP (A-ATP@Fe3O4), indicating that Fe3O4 nano-particles were embedded in the ATP
The results indicated that the maximum Total organic carbon (TOC) removal rate was approximately 45% after 20 min, suggesting that 45% of EtBr was oxidized by active species(∙OH, ∙O2−, etc.) to CO2 and H2O

Summary

Introduction

Ethidium bromide (EtBr) is widely employed for rapid visualization of nucleic acids in electrophoretic gels and is commonly used in the life sciences[1]. To improve degradation catalytic ability, Fe3O4 nanoparticles are commonly supported by clay minerals such as bentonite[17], carbon nano-material[18, 19], and fly ash[20], etc. Fe3O4 nanoparticles can degrade organic contamiants by generating free radicals, but are paramagnetic which facilitate easy separation, from aqueous solution[26]. ATP supported Fe3O4 nanoparticles is capable of degradation of organic contaminants, but easy to be seperated from solutions. Thereby, Fe3O4-ATP nanoparticles were prepared and their physical and chemical characteristics were determined The applicability of this composite in heterogeneous Fenton reaction was evaluated in view of the effect of the main variables (pH, temperature and H2O2 concentration, and catalyst dosage), reaction kinetics, and material stability, as well as the degradation mechanism

Methods

Results

Conclusion