Efficient activation of peroxymonosulfate by hollow cobalt hydroxide for degradation of ibuprofen and theoretical study

Hollow microsphere structure cobalt hydroxide (h-Co(OH)₂) was synthesized via an optimized solvothermal-hydrothermal process and applied to activate peroxymonosulfate (PMS) for degradation of a typical pharmaceutically active compound, ibuprofen (IBP). The material characterizations confirmed the presence of the microscale hollow spheres with thin nanosheets shell in h-Co(OH)₂, and the crystalline phase was assigned to α-Co(OH)₂. h-Co(OH)₂ could efficiently activate PMS for radicals production, and 98.6% of IBP was degraded at 10 min. The activation of PMS by h-Co(OH)₂ was a pH-independent process, and pH 7 was the optimum condition for the activation-degradation system. Scavenger quenching test indicated that the sulfate radical (SO₄^{? ?}) was the primary reactive oxygen species for IBP degradation, which contributed to 75.7%. Fukui index (f ^?) based on density functional theory (DFT) calculation predicted the active sites of IBP molecule for SO₄^{? ?} attack, and then IBP degradation pathway was proposed by means of intermediates identification and theoretical calculation. The developed hollow Co(OH)₂ used to efficiently activate PMS is promising and innovative alternative for organic contaminants removal from water and wastewater.