An easily recyclable Co/SBA-15 catalyst: Heterogeneous activation of peroxymonosulfate for the degradation of phenol in water

Abstract

A powder Co/SBA-15 catalyst for the activation of peroxymonosulfate (PMS) and the subsequent degradation of phenol was prepared through an incipient wetness impregnation technique using SBA-15 as the support, Co(NO3)2·6H2O as the precursor. A facile way to make a recyclable Co/SBA-15 catalyst was tested. The samples synthesized were characterized by X-ray diffraction (XRD), N2 adsorption–desorption, high-resolution transmission electron microscopy (HRTEM) and scanning electron microscopy (SEM) techniques. Effects of Co loading, calcination temperature and time on the performance of the powder catalyst were investigated. The results show that Co3O4 was the main cobalt species present both inside and outside the support. Heat treatment led to the formation of Co–O–Si species during the calcinations and significantly inhibited Co leaching. The 10wt%Co/SBA-15 calcined at 400°C for 5h had the best performance, with the phenol removal of more than 98% and total organic carbon (TOC) reduction of approximately 98%. The complete mineralization of phenol degradation was demonstrated, and the degradation mechanism was analyzed. Moreover, effects of PMS dosages and phenol concentrations on phenol degradation were also investigated. The results show that the appropriately high PMS dosage and the low phenol concentration were favorable to phenol removal. During 25 runs of recycling tests, the powder Co/SBA-15 wrapped with polytetrafluoroethylene (PTFE) membranes always maintained high catalytic activity with the phenol removal more than 90% in 2h and Co leaching of less than 85μg/L. Consequently, it is an easily recyclable catalyst.