MnCeO_x/diatomite catalyst for persulfate activation to degrade organic pollutants

Persulfate (PS)-based oxidation technologies are attracting increasing attentions in water treatment due to their high efficiency and stability. In this study, a novel diatomite supported MnCeO_x composite (MnCeO_x/diatomite) was prepared and characterized for activation of PS to degrade organic pollutants. Results indicated that diatomite not only dispersed MnCeO_x and increased the specific surface area of catalyst, but also improved the low-valence metal site (Mn²⁺ and Ce³⁺) and reactive oxygen species site (-OH) of MnCeO_x, thus enhancing the activities of MnCeO_x. MnCeO_x/diatomite/PS showed high efficiency for multiple dyes and pharmaceutical pollutants. Constant rate (k) of MnCeO_x/diatomite (k_{MnCeOx/diatomite}) was three times higher than the sum of constant rate of MnCeO_x (k_MnCeOx) and constant rate of diatomite (k_diatomite). In addition, MnCeO_x/diatomite showed wide pH application (5-9). Cl^- and NO₃^2- had no effect while SO₄^2- and humid acid had slightly negative effects on MnCeO_x/diatomite/PS system. Moreover, MnCeO_x/diatomite showed good reusability and stability. Mechanism analyses indicated that electron transfer of Mn and Ce attributed to the activation of PS and oxygen to produce free radicals. SO₄^-, OH and O₂^- on the surface of catalyst were the main active free radicals to attack pollutants.