Heterogeneous activation of peroxymonosulfate by hierarchical CuBi2O4 to generate reactive oxygen species for refractory organic compounds degradation: morphology and surface chemistry derived reaction and its mechanism.

Activation of peroxymonosulfate (PMS) by a novel hierarchical CuBi2O4 generated reactive oxygen radical for degradation refractory organic compounds in aqueous solution, which would be controlled by the morphology and surface chemistry of solid catalyst. It's found that the activation ability of CuBi2O4 toward PMS was highly dependent on the morphology and surface hydroxyl group, as using rhodamine B (RhB) as the model compound. The spherical CuBi2O4, which possessed higher density of surface hydroxyl group, exhibited better catalytic activity in RhB degradation than scattered cluster CuBi2O4, and as-prepared CuBi2O4 could efficiently activated PMS to degrade RhB within a wide pH range as an absolute heterogeneous process. The emerging organic chemicals, including bisphenol A, 1H-benzotriazole, and carbamazepine, could also be effectively removed in this novel CuBi2O4/PMS. Furthermore, activation mechanism of PMS by as-prepared CuBi2O4 was proposed, the existence of surface hydroxyl group bonded with Cu(II), and inward electron transfer cycling reaction between Cu(II)/Cu(I) facilitated the effective activation of PMS to generate SO4·- and ·OH. In addition, the intermediates of RhB formed in this process were identified by silylation derivatation-GC-MS and LC-high-resolution MS/MS, and degradation pathway was proposed.