title: Sulfate Radical-Mediated Degradation of Sulfadiazine by CuFeO2 Rhombohedral Crystal-Catalyzed Peroxymonosulfate: Synergistic Effects and Mechanisms.
abstract: Copper-iron bimetallic oxides have shown great potential for powerful radical production by activating peroxides. In this work, CuFeO2 rhombohedral crystals (RCs) were synthesized and used as heterogeneous catalysts for peroxymonosulfate (PMS) activation under various conditions. Sulfadiazine, a widely used veterinary sulfonamide, was used as a target pollutant to evaluate the efficiency of this combination. The results showed that of all the catalysts tested, the CuFeO2 RCs had the greatest reactivity. Under conditions of 0.1 g L(-1) CuFeO2 RCs and 33.0 μM PMS, the nearly complete degradation of sulfadiazine occurred within 24 min. A synergistic catalytic effect was found between solid Cu(I) and Fe(III), probably due to the accelerated reduction of Fe(III). The two activation stages that produced different radicals (hydroxyl radicals followed by sulfate radicals) existed when solid Cu(I) was used as the catalyst. The CuFeO2 RCs had a higher PMS utilization efficiency than CuFe2O4, probably because the Cu(I)-promoted reduction of solid Fe(III). A total of 10 products were identified, and their evolution was explored. On the basis of the evidence of oxidative product formation, we proposed four possible pathways of sulfadiazine degradation.
authors.affiliation: Department of Civil Engineering, The University of Hong Kong , Pokfulam Road, Hong Kong, People's Republic of China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Feng
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science & Engineering, Tongji University , Shanghai 200092, People's Republic of China.
authors.forename: Deli
authors.initials: D
authors.lastname: Wu
authors.affiliation: Department of Civil Engineering, The University of Hong Kong , Pokfulam Road, Hong Kong, People's Republic of China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Deng
authors.affiliation: Department of Civil Engineering, The University of Hong Kong , Pokfulam Road, Hong Kong, People's Republic of China.
authors.forename: Tong
authors.initials: T
authors.lastname: Zhang
authors.affiliation: Department of Civil Engineering, The University of Hong Kong , Pokfulam Road, Hong Kong, People's Republic of China.
authors.forename: Kaimin
authors.initials: K
authors.lastname: Shih
mesh_terms: D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D005296:Ferrous Compounds / Q000737:chemistry*; D017665:Hydroxyl Radical / Q000737:chemistry; D010084:Oxidation-Reduction; D010545:Peroxides / Q000737:chemistry; D013411:Sulfadiazine / Q000737:chemistry*; D013431:Sulfates / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry
chemical_list: C523076:CuFe2O4; D005296:Ferrous Compounds; D010545:Peroxides; D013431:Sulfates; D014874:Water Pollutants, Chemical; C069025:sulfate radical; D013411:Sulfadiazine; C038288:peroxymonosulfate; D017665:Hydroxyl Radical; D003300:Copper