[Study on the degradation of AO7 by UV/K2S2O8, system: kinetics and pathways].
The UV photolysis of S2O8(2-) is a novel advanced oxidation technologies (AOTs), which leads to the formation of strong oxidizing radicals, sulfate radicals (SO4(*-)). The effect of oxidant K2S2O8 concentration, the initial pH of solution and various inorganic anions (H2PO4-, HCO3-, NO3- and Cl-) were investigated using AO7, a kind of azo dye, as a model pollutant. The degradation kinetics of AO7 followed pseudo first-order kinetics and reaction rates related to PMS concentrations. When the initial concentration of AO7 was 0.14 mmol/L, the optimal molar ratio of oxidant K2S2O8 to pollutants AO7 was 20. The effect of initial pH had great effect on the AO7 degradation rate during UV/K2S2O8 system. Increasing system pH results in the formation of *OH from SO4(*-). The effects of four inorganic anions (H2PO4-, HCO3-, NO3- and Cl-) all had some negative effect on the degradation of AO7. Based on the results of GC/MS, three main intermediates (2-naphthalenol, coumarin and 1,2-benzenedicarboxylic acid) were identified, thus the degradation pathway for SO4(*-) induced by UV/K2S2O8 was proposed accordingly.
Chen
Xiao-yang
XY
Institute of Environmental Resource & Soil Fertilizer, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China. xiaoyangchen@yahoo.cn
Wang
Wei-ping
WP
Zhu
Feng-xiang
FX
Hong
Chun-lai
CL
Xue
Zhi-yong
ZY
D001391:Azo Compounds / Q000737:chemistry / Q000302:isolation & purification*; D001557:Benzenesulfonates / Q000737:chemistry / Q000302:isolation & purification*; D004396:Coloring Agents / Q000737:chemistry / Q000302:isolation & purification; D007700:Kinetics; D010084:Oxidation-Reduction; D010782:Photolysis; D013431:Sulfates / Q000737:chemistry*; D014466:Ultraviolet Rays; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods*
D001391:Azo Compounds; D001557:Benzenesulfonates; D004396:Coloring Agents; D013431:Sulfates; D014874:Water Pollutants, Chemical; C014722:2-naphthol orange