Some researchers reported that lattice oxygen  and  surface  hydroxyl  groups  are  active  oxygen  species,  and that  they  play  a  critical  role  in  oxidation  reaction. In heterogeneous catalyst (CoFe2O4) both lattice oxygen (O2−) and surface hydroxyl (OH) species involved for activation of PMS to generate SO4−• and •OH radicals. How it will be explain, the role of O2− and OH species in heterogeneous CoFe2O4 catalyst for the activation of PMS?