Cold plasma pretreatment of ramsdellite-MnO2 to enhance remediation of antibiotic rifampicin from water by the self-generated reactive oxygen species

Pathway design for reactive oxygen species (ROS) production has raised great interest for advanced oxidation in water treatment. Herein, the surface oxygen vacancies (OVs) on ramsdellite-type MnO 2 were modified via atmospheric-pressure DBD plasma. By simply submitting the MnO 2 powder to N 2 discharge zone, the abundance and reactivity of OVs were improved at a low processing energy (input power 14 W) and after moderate processing time of 20 min (N14-20). The structures were characterized with XRD, FTIR, SEM, (HR)TEM, XPS and CO-TPR. The activities for rifampicin oxidation were evaluated without light illumination, thermal activation or any additional oxidant. The phase composition and surface functional groups were not changed after DBD-N 2 -plasma treatment, but the original big nanorods were collapsed into small flakes. Compared with •OH and 1 O 2 , O 2 •- served as primary ROS for rifampicin degradation. In this process, the dissolved oxygen (DO) in water was the precursor of ROS, and the larger amount of surface OVs on N14-20 remarkably facilitated DO activation into O 2 •- , perfectly eliminating rifampicin ( e.g. , removal for 60 mg/L rifampicin by 0.003 g catalyst was ∼ 70 % for N14-20 and ∼ 60 % for virgin MnO 2 ; removal for 100 mg/L rifampicin by 0.01 g catalyst was 68 % and 53 %, respectively).