超声对水中双酚A的降解动力学及影响因素

Kinetics and Influence Factors of Ultrasonic Degradation of Bisphenol A in Water

摘要:

采用800 kHz频率的超声对双酚A(BPA)的降解效果和动力学规律进行研究.通过投加不同的物质(如叔丁醇、H2O2、腐殖酸)和向水中曝气等,考察不同因素对超声降解BPA的影响.结果表明,超声对BPA的降解过程符合准一级动力学,其降解速率随BPA初始浓度的增加而降低.投加叔丁醇明显抑制BPA的降解,证明BPA的降解途径主要是羟基自由基（?OH）氧化.当投加H2O2浓度为0.1 mmol?L-1时,能将BPA的降解速率提高32%;随着H2O2投加量的进一步增加,与BPA的摩尔比>200时,降解速率不升反降.溶液中存在腐殖酸会同BPA竞争?OH,并随着腐殖酸浓度的增加,BPA的降解速率下降.额外曝气会干扰BPA分子靠近空化泡界面,阻碍与?OH的反应,不利于BPA的降解.

Abstract:

The effect and kinetics of degradation of bisphenol A (BPA) by ultrasonic at the frequency of 800 kHz were studied.The effects of some additives,such as t-butyl alcohol,H2O2,humic acid and air bubbles,were investigated as external factors.The results show that the ultrasonic degradation of BPA follows a pseudofirst order kinetic model and the rate constant decreases with the increasing initial concentration.It is identified that hydroxyl radical is a major participant in the ultrasonic degradation of BPA by t-butyl alcohol.The rate constant increases by 32% at low H2O2 concentration of 0.1 mmol?L-1.However,the degradation of BPA is hindered with the further addition of H2O2.The boundary point of the molar rate is about 200:1 between H2O2 and BPA.Moreover,humic acid in aqueous solution hinders the degradation of BPA and the rate constant decreases with the increasing humic acid dose.The common bubbles added can prevent BPA from closing to the interface of cavitation bubble and reacting with ?OH,which is adverse to the degradation of BPA.