MOF-derived Co3O4-C@FeOOH as an efficient catalyst for catalytic ozonation of norfloxacin

Metal-organic frameworks (MOFs) ZIF-67-derived Co3O4-C@FeOOH composite was prepared, characterized and used as an efficinet catalyst for ozonation of norfloxacin (NOF). Results showed that ZIF-67-derived Co3O4-C composite maintained the polyhedral structure of ZIF-67. After modification, abundant amorphous FeOOH nanowire attached on the surface of Co3O4-C composite, resulting in Co3O4-C@FeOOH interwoven polyhedrons. Furthermore, the specific surface area of the formed composite was about 2.5 times that of Co3O4-C composite, which might provide more active sites for catalytic reaction. Compared with single ozonation system, the catalytic ozonation process (Co3O4-C@FeOOH/O3) had better performance in NOF mineralization under the same operating conditions. Moreover, in the presence of Co3O4-C@FeOOH, faster O3 decomposition and higher •OH concentration were observed, which could explain the significant enhancement of TOC removal. The co-existence of Fe and Co in various valence states in catalyst might improve the conversion of Co(III)/Co(II) and Fe(III)/Fe(II), which would increase the catalytic activity in catalytic ozonation process. Besides, several main intermediate products were detected and possible NOF degradation pathway was proposed.