科研之友
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摘要
Hexavalent chromium (Cr(VI)) removal from aqueous solution with magnetic manganese ferrite has been demonstrated to be an effective method, however, its wide application is restricted as manganese ferrite was easy to aggregate by magnetism. Meanwhile, the effect of dissolved oxygen on the performance of magnetic manganese ferrite was still unclear. Hence, this study aimed to investigate the influence of ultrasound pretreatment and dissolved oxygen on Cr(VI) removal efficiency with manganese ferrite nanoparticles. The characterization results of pristine manganese ferrite indicated that the prepared nanoparticles were spherical with diameter around 200 nm, and the valence for manganese and iron element were + 2 and +3, respectively. Subsequently, we compared the removal percentage of Cr(VI) in the presence or absence of dissolved oxygen with or without ultrasound pretreatment, and the results demonstrated that ultrasound pretreatment and the presence of dissolved oxygen increased the Cr(VI) removal percentage to 100%. Moreover, the high-resolution X-ray photoelectron spectroscopy (HR-XPS) results exhibited that the valence of Mn and Fe element did not changed during the Cr(VI) removal process, suggesting that Cr(VI) was separated from water via adsorption pathway. This deduction could be further verified by the HR-XPS spectra of Cr 2p after the reaction in the Ar and air condition. This research revealed the effect of ultrasound pretreatment and dissolved oxygen on Cr(VI) removal with manganese ferrite and provided fundamental theory for the wide application of magnetic manganese ferrite for water treatment.
