十二烷基苯磺酸钠对乐果在水-气界面挥发动力学的影响研究

以有机磷农药乐果为研究对象,研究了不同浓度的阴离子型表面活性剂十二烷基苯磺酸钠(SDBS)存在时,乐果在水-气界面的挥发行为,以进一步认识农药的迁移转化规律,为复合污染水体中表面活性剂对有机物挥发的影响提供理论依据.研究结果表明:在试验条件下,乐果水溶液在水-气界面的恒温挥发过程符合一级动力学,并且其挥发行为受到表面活性剂的影响作用显著.不同浓度的表面活性剂对乐果挥发的影响不同,与未加入表面活性剂时乐果的挥发情况相比,当加入的SDBS浓度小于临界胶束浓度(CMC)时对乐果的挥发具有促进作用;当SDBS浓度超过CMC,乐果的挥发行为受到抑制,挥发速率开始变小.

Effect of SDBS on Volatilization of Dimethoate at the Water-Air Interphase

The volatility behavior of organophosphate insecticide dimethoate at the water-air interface was studied in the presence of surfac-tant sodium dodecylbenzene sulfonate(SDBS), in order to investigate the effect of surfactant on the pollutants evaporation in water system. The results showed that the volatilization process of dimethoate could be described by the first-order kinetic equation at constant temperature, and was significantly influenced in the presence of SDBS. The volatility of dimethoate was accelerated when the concentration of SDBS was below the critical micelle concentration (CMC), however, the volatility was inhibited due to the formation of surfactant micelles when the sur-factant concentration exceeded the CMC. The reason may be that when the surfactant concentration was less than the CMC, the reduction of the surface tension was beneficial to volatilization, when it was above the CMC, the surface tension kept constant, however the amount of the micelles increased, because of the adsorption and revetment of the surfactant micelles, the volatility behavior was restrained.