Ce-based catalysts used in advanced oxidation processes for organic wastewater treatment: A review

Refractory organic pollutants in water threaten human health and environmental safety,and advanced oxidation processes (AOPs) are effective for the degradation of these pollutants.Catalysts play vital role in AOPs,and Ce-based catalysts have exhibited excellent performance.Recently,the development and application of Ce-based catalysts in various AOPs have been reported.Our study conducts the first review in this rapid growing field.This paper clarifies the variety and properties of Ce-based catalysts.Their applications in different AOP systems (catalytic ozonation,photodegradation,Fenton-like reactions,sulfate radicalbased AOPs,and catalytic sonochemistry) are discussed.Different Ce-based catalysts suit different reaction systems and produce different active radicals.Finally,future research directions of Ce-based catalysts in AOP systems are suggested.

MnCeOx/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 MnCeOx composite(MnCeOx/diatomite) was prepared and characterized for activation of PS to degrade organic pollutants.Results indicated that diatomite not only dispersed MnCeOx and increased the specific surface area of catalyst,but also improved the low-valence metal site(Mn^2+and Ce^3+) and reactive oxygen species site(-OH) of MnCeOx,thus enhancing the activities of MnCeOx.MnCeOx/diatomite/PS showed high efficiency for multiple dyes and pharmaceutical pollutants.Constant rate(k) of MnCeOx/diatomite(kMnCeOx/diatomite) was three times higher than the sum of constant rate of MnCeOx(kMnCeOx)and constant rate of diatomite(kdiatomite).In addition,MnCeOx/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 MnCeOx/diatomite/PS system.Moreover,MnCeOx/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.