title: Degradation of diphenylamine by persulfate: Performance optimization, kinetics and mechanism.
abstract: The degradation of diphenylamine (DPA) in aqueous solution by persulfate is investigated. Effects of pH, persulfate concentration, ionic strength, temperature and catalytic ions Fe(3+) and Ag(+) on the degradation efficiency of DPA by persulfate are examined in batch experiments. The degradation of DPA by persulfate is found to follow the pseudo-first-order kinetic model. Increasing the reaction temperature or persulfate concentration may significantly accelerate the DPA degradation. Fe(3+) and Ag(+) ions can enhance the degradation of DPA, and Ag(+) ion is more efficient than Fe(3+) ion. However, the increase of either the pH value or ionic strength will decrease the rate of DPA degradation. N-Phenyl-4-quinoneimine, N-carboxyl-4-quinoneimine, 4-quinoneimine and oxalic acid are identified as the major intermediates of DPA degradation, and a primary pathway for the degradation of DPA is proposed. The degradation of DPA in surface water, groundwater and seawater is also tested by persulfate, and more than 90% of DPA can be degraded at room temperature in 45min at an initial concentration of 20mgL(-1).
authors.affiliation: Department of Chemistry, Sichuan University of Science & Engineering, Zigong City, Sichuan Province, China.
authors.forename: Shen-Xin
authors.initials: SX
authors.lastname: Li
authors.forename: Dong
authors.initials: D
authors.lastname: Wei
authors.forename: Nai-Ki
authors.initials: NK
authors.lastname: Mak
authors.forename: ZongWei
authors.initials: Z
authors.lastname: Cai
authors.forename: Xiang-Rong
authors.initials: XR
authors.lastname: Xu
authors.forename: Hua-Bin
authors.initials: HB
authors.lastname: Li
authors.forename: Yue
authors.initials: Y
authors.lastname: Jiang
mesh_terms: D004159:Diphenylamine / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009994:Osmolar Concentration; D017680:Potassium Compounds / Q000737:chemistry*; D013431:Sulfates / Q000737:chemistry*; D013696:Temperature; D014874:Water Pollutants, Chemical / Q000737:chemistry; D018508:Water Purification / Q000379:methods*
chemical_list: D017680:Potassium Compounds; D013431:Sulfates; D014874:Water Pollutants, Chemical; C009007:potassium persulfate; D004159:Diphenylamine