Graphite assisted room-temperature synthesis of structurally defected OMS-2 nanorods for peroxymonosulfate activation.

Structurally defected cryptomelane-type octahedral molecular sieve (SDOMS-2) was successfully prepared at room temperature for efficient activation of peroxymonosulfate (PMS). The catalyst was easily fabricated by redox reaction of acidic KMnO 4 and MnSO 4 with the presence of graphite at 25 °C for 96 h. XRD and N 2 adsorption-desorption measurements confirmed the OMS-2 crystal with a high surface area of 118 m2/g. Evidence by Raman, XPS, cyclic voltammogram (CV), SEM and TEM, the slow-growing SDOMS-2 nanorods exhibited more structural defects and lower valance of manganese than the conventional OMS-2 prepared by a refluxing method. The SDOMS-2 catalyst showed high activity and stability in terms of Acid Orange 7 (AO7) degradation in the presence of PMS, and the initial degradation rate was 4 times of the refluxed OMS-2. Synthesis conditions influenced the surface morphology and detective structure of OMS-2, and thus appeared to play critical roles in PMS activation. Based on the scavenger experiments, 1O 2 was identified as dominant oxygen species in the SDOMS-2 + PMS system for AO7 degradation. This study demonstrates a novel and simple technology for the preparation of SDOMS-2 for PMS activation. Unlabelled Image • Structural defective OMS-2 nanorods were successfully prepared at room temperature. • Activation of PMS using structurally defected OMS-2 showed a superior effect on degradation of AO7. • O 2 ●- and 1O 2 , rather than SO 4 -● and HO•, were the dominant species responsible for the degradation. [ABSTRACT FROM AUTHOR]