Efficient removal of organic contaminant via activation of potassium persulfate by γ-Fe2O3/α-MnO2 nanocomposite

In this study, gamma-Fe2O3/alpha-MnO2 nanocomposite, which possesses magnetism as well as excellent activation performance for potassium persulfate (PS) to degrade organic contaminants in water, was successfully fabricated through ultrasonic strategy. Noted, proportion between gamma-Fe2O3 and alpha-MnO2 was optimized to achieve excellent magnetic and activation performance. Also, physicochemical properties of magnetic nanocomposite material (gamma-Fe2O3/alpha-MnO2 1/7, FM1-7) are investigated by SEM, EDS, BET, XRD, TEM, XPS and vibrating sample magnetometer (VSM). Results show that gamma-Fe2O3 nanoparticles is connected with alpha-MnO2 nanorods successfully, what's more, FM1-7 nanocomposite crystal structure is intact and its crystallinity is excellent. Besides, in gamma-Fe2O3/alpha-MnO2/PS reaction system, about 92.79% of Rhodamine B could be removed within 30 min. The result proves that when the gamma-Fe2O3 content is 12.5%, gamma-Fe2O3/alpha-MnO2 nanocomposite exhibits superior activation performance. gamma-Fe2O3/alpha-MnO2/PS reaction shows the most excellent degradation towards Rhodamine B when it is compared with another reaction systems. Most importantly, in this study, the crucial role of gamma-Fe2O3 and catalysis mechanism of gamma-Fe2O3/alpha-MnO2 is also discussed in detail. In the Fenton-like system mediated by Fe(III) and Mn(IV), the redox reactions with the activation of PS happen on the surface of gamma-Fe2O3/alpha-MnO2. Therefore, strong oxidizers of SRs (SO4 center dot-), hydroxyl radicals ((OH)-O-center dot) and even superoxide anion (O-center dot(2)-) may be generated and participated in the degradation of Rhodamine B. What's more, the result of repetitive experiment illustrates that magnetic FM1-7 sample possesses good recycle and reusability capacities. This study not only provides a feasible strategy to prepare catalyst which could be used to active PS, but also is expected to be applied to deal with many kinds of contaminants removal problem according to the practical requirement.