低频超声辅助电催化降解水中抗菌药氟康唑

Low-frequency ultrasound assisted electrocatalytic degradation of antimicrobial fluconazole in water

采用低频超声(20kHz,78W)辅助电催化氧化(Ti/SnO_(2)-Sb/La-PbO_(2)阳极)去除水中氟康唑,并考察其降解机制.低频超声不能有效降解氟康唑,但低频超声辅助提高阳极表面•OH产率(81.95倍)、污染物的传质效率和电极微界面电子传递能力,进而使氟康唑电催化降解准一级动力学常数由0.134min−1提升至0.180min−1、矿化动力学常数提升29.03%.当超声功率从26W提高至130W时,氟康唑的降解动力学常数提高42.68%;电流密度从2mA/cm^(2)升至20mA/cm^(2),氟康唑的降解动力学常数提升24.00倍.氟康唑的主要降解机理为•OH间接氧化(贡献率:82.45%~85.71%),主要降解路径为脱氟、断键、环化和氧化,最终生成甲酸、草酸、NO_(3)^(-)和F^(−)等小分子产物.

Low-frequency ultrasound(20kHz,78W)assisted electrochemical oxidation(Ti/SnO_(2)-Sb/La-PbO_(2) as the anode)was used to eliminate aqueous fluconazole,and the degradation mechanism was further investigated.Fluconazole cannot be directly degraded by low-frequency ultrasound.The acceleration electrochemical degradation of fluconazole might be ascribed to the increased•OH electrochemical production(81.95 times)under low-frequency ultrasound.Moreover,the mass transfer rate and the electron transfer ability at the electrode interface were also enhanced,which were conducive to the electrochemical degradation of fluconazole.The reaction rate constants of fluconazole degradation increased by 42.68%when the ultrasound power increased from 26W to 130W,and increased by 24.00 times when the current density increased from 2mA/cm^(2) to 20mA/cm^(2).The main degradation mechanism of fluconazole was the indirect oxidation of•OH(relative contribution of 82.45%~85.71%).Fluconazole was degraded by defluorination,bond cleavage,cyclization and oxidation,followed by the formation of formic acid,oxalic acid,NO_(3)^(-)and F^(−).