研究了地下水环境条件下(低温、避光、特征离子共存等),金霉素在二氧化锰和铁锰复合氧化物上的降解行为.探讨了降解动力学以及pH条件、离子种类和强度等环境因素对降解的影响,并通过降解反应前后材料的变化,初步探索其降解机理.一级动力学方程能较好地拟合降解过程,铁锰复合氧化物的降解速率常数高于二氧化锰;外源阳离子K^+、Na^+、Ca^2+、Mg^2+对降解无显著影响,但阴离子HCO_3~-对降解有明显抑制.采用红外光谱对降解前后材料进行表征,发现二氧化锰上的Mn—OH和铁锰复合氧化物上的Fe—OH、Mn—O和Fe—O—Mn振动吸收峰在降解后明显减弱,表明这些可能为降解金霉素的活性位点,降解后材料能谱图上N、Cl元素的存在也同样证明金霉素在材料表面发生了氧化反应.
The degradation behaviors of chlortetracycline by iron and manganese oxides were studied under simulated groundwater environment( low temperature,dark and typical coexisting ions). The degradation kinetics and factors such as p H,species and dosages of ions,were investigated. And the degradation mechanisms were discussed through the changes of oxide materials before and after use.First-order reaction kinetic equation fitted the degradation processes of chlortetracycline by two oxides and the kinetic constants of the degradation by Fe-Mn bimetal oxides were generally higher than that by manganese dioxide. The coexisting HCO_3~- showed inhibition on the degradation efficiency of chlortetracycline,whereas cations exhibited no influence on it. Fourier transform infrared( FTIR)spectra showed that the vibration absorption intensities of Mn—OH in manganese dioxide,Fe—OH,Mn—O,and Fe—O—Mn in Fe-Mn bimetal oxides decreased,which suggested that they might be the active sites points. The existences of N and Cl elements on the used oxide materials,demonstrated by scanning electron microscope-energy dispersive spectrometer( SEM-EDS),also proved the oxidation reaction of chlortetracycline on the material surface.