超声气升式环流反应器降解乐果水溶液的动力学研究

采用超声气升式环流反应器(UALR),以臭氧气体为氧化剂,以有机磷农药乐果为典型污染物,研究其降解反应动力学规律.通过对乐果降解过程的表观动力学研究,发现乐果在单独超声辐射(不通入气体,即臭氧)、臭氧(O3)氧化和超声气升式环流反应器(UALR/O2)协同下的降解均符合表观一级动力学.在乐果初始质量浓度为50 mg/L、溶液初始pH为6.0、反应液体积80 mL、超声声强0.5W/cm2、O3流量200 L/h、温度20℃、处理时间4h的条件下,采用超声(US)、O3和UALR/O3工艺,乐果的去除率分别为27%、15%和90%,乐果降解的速率常数增强因子可达到4.816.进一步从UALR/O3系统中存在US、O3和羟基自由基(·OH)协同作用的降解机理,推导出了简化的机理动力学模型.

Kinetics on Dimethoate Aqueous Solution Degradation in Ultrasonic Airlift Loop Reactor

The kinetic rules of degradation were studied in ultrasonic airlift loop reactor (UALR) in which O3 was introduced as oxidant and the organophosphorus pesticide dimethoate was used as typical contaminant. It was found that the dimethoate degradations under the individual ultrasonic radiation treatment without O3 (US), the oxidation of O3 gas (O3) and the synergetic effect of UALR and O3 (UALR/O3) were all consonant with the apparent first-order reaction by the kinetics investigations. The dimethoate removal rates of US, O3 and UALR/O3 methodologies under the conditions of dimethoate initial concentration of 50 mg/L, initial solution pH of 6.0, dimethoate solution volume of 80 mL, ultrasonic intensity of 0.5 W/cm2, O3 flow of 200 L/h, temperature of 20 degrees C and the treatment time of 4 h were 27%, 15% and 90%, respectively. Under these conditions, the rate constant enhancement factor of dimethoate degradation reached 4.816. Furthermore, a simplified mechanistic kinetic model was derived from the degradation mechanism of the synergetic effect of US, O3 and hydroxyl free radical (*OH) in the UALR/O3 system.