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 KMnO4 and MnSO4 with the presence of graphite at 25 degrees C for 96 h. XRD and N-2 adsorption-desorption measurements confirmed the OMS-2 crystal with a high surface area of 118 m(2)/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, O-1(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.