Hydrogen titanate nanosheet-assembled fibers as a new matrix to promote the Co-activated PMS process for efficient polychlorinated phenol degradation

Developing highly efficient catalysts to effectively activate peroxymonosulfate (PMS) is a key challenge for degrading polychlorinated phenols posing a long-term risk of toxicity to environmental water. Here, a novel surface hierarchically nanostructured Co3O4/hydrogen titanate (HTO) composite catalyst (Co3O4/HTO) was prepared using electrospinning technology followed by a low-temperature alkaline hydrothermal process. Such a structural design endows the Co-based composite catalysts with rich and efficient surface-active cobalt sites, and provides rich hydroxyl groups for the composite catalyst, both of which enhance the catalytic performance of the composite catalyst in PMS based reactions. As expected, the optimum Co3O4/HTO catalyst can efficiently catalyze PMS to produce large amounts of free radicals, enabling the degradation of 2,4-dichlorophenol (2,4-DCP) completely within a very short time period (nearly 10 min). Density functional theory calculation further demonstrated that the Co3O4/HTO catalyst helps to enrich the charge density of PMS for the easy breakdown of the O-OH bond to generate more free radicals than the single Co3O4 catalyst. By analyzing the free radicals and intermediate products generated in catalytic reactions, possible degradation mechanisms and pathways of 2,4-DCP were proposed. This work offers a new approach to design low-cost and highly active PMS activators for the purification of wastewater.