title: [Sodium peroxydisulfate activation by heat and Fe(II) for the degradation of 4-CP].
abstract: The heat and ferrous ion-activated sodium peroxydisulfate (PDS) for the oxidation of 4-chlorophenol (4-CP) was investigated. These processes are based on the generation of sulfate radicals, which are powerful oxidizing species found in nature. The effects of temperature, pH, the initial concentrations of Fe (II), PDS and citric acid on the degradation efficiencies of 4-CP were studied. The results show that the degradAtion efficiency of 4-CP is significantly enhanced as temperature increases. The degradation efficiencies of 4-CP are 2.5% and 43.5% within 4 h at 30 degrees C and 50 degrees C, respectively. Moreover, 4-CP is degraded completely at 60 degrees C. The degradation efficiency of 4-CP follows the order: pH 4.0 > pH 7.0 > pH 10.0. In the PDS/Fe (II) system, ferrous ion played an important role in generating sulfate radicals at ambient temperature. The optimum experimental condition is established and the addition of probe compounds proves the formation of sulfate radicals. Furthermore, the iron availability in the aqueous solution is manipulated with the optimum amount of citric acid, as a chelating agent. The degradation efficiency of 4-CP is 50.9% in the PDS/Fe (II)/citric acid system, which is superior to 43.5% at 50 degrees C under the same initial concentration of PDS.
authors.affiliation: Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education, School of Environmental and Biological Science and Technology, Dalian University of Technology, Dalian 116024, China. zhaojinying2002@yahoo.com.cn
authors.forename: Jin-ying
authors.initials: JY
authors.lastname: Zhao
authors.forename: Yao-bin
authors.initials: YB
authors.lastname: Zhang
authors.forename: Xie
authors.initials: X
authors.lastname: Quan
authors.forename: Ya-zhi
authors.initials: YZ
authors.lastname: Zhao
mesh_terms: D001673:Biodegradation, Environmental; D002733:Chlorophenols / Q000737:chemistry / Q000302:isolation & purification*; D019343:Citric Acid / Q000737:chemistry; D005296:Ferrous Compounds / Q000737:chemistry*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D010084:Oxidation-Reduction; D017670:Sodium Compounds / Q000737:chemistry*; D013431:Sulfates / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000302:isolation & purification*
chemical_list: D002733:Chlorophenols; D005296:Ferrous Compounds; D017670:Sodium Compounds; D013431:Sulfates; D014874:Water Pollutants, Chemical; D019343:Citric Acid; C029107:4-chlorophenol; C024625:sodium persulfate