表面活性剂对苯系物在静水面挥发的影响

以苯、甲苯和乙苯为苯系物(BTEX)的目标化合物 ,研究了十二烷基苯磺酸钠(SDBS)、十六烷基三甲基溴化铵(CTMAB)和月桂醇聚氧乙烯(4)醚(Brij30)共存时,BTEX在静水面的挥发及机理 ,为复合污染的水体中表面活性剂对有机物挥发的影响提供理论依据 .结果表明 ,在所测浓度范围内 ,表面活性剂浓度大于临界胶束浓度 (CMC)且分别达到1000mg/L、2000mg/L和3000mg/L 时 ,乙苯、甲苯和苯的挥发速率分别开始变小 ,挥发半衰期值(t_1/2)变大 .胶束的形成 ,减小了BTEX在液膜和液相中的浓度比(α) ,使BTEX在静水面的挥发速率降低 .CTMAB和Brij30对苯系物在静水面挥发速率的抑制作用明显强于SDBS .相同表面活性剂对BTEX挥发速率的抑制作用与BTEX的辛醇 水分配系数 (Kow)和亨利系数(H)均呈正相关 .

Effect of Surfactant on the Evaporation of BTEX from Static Water

Effect of surfactant on the evaporative loss of benzene, toluene and ethylbenzene from static water was researched and the mechanism of surfactant was studied, so as try to supply theoretical reference for the effect of surfactant on the evaporation of complex pollution in water system. Sodium dodecylbenzene sulfonate(SDBS), cetyltrimethyl ammonium bromide(CTMAB) and polyoxyethylene(4) lauryl ether(Brij30) were used in the experiment. The results show when the surfactant concentrations exceeded their critical micelle concentrations (CMCs) and were set above 1 000mg/L, 2 000mg/L and 3 000mg/L respectively, the evaporative loss velocity of ethylbenzene, toluene and benzene began to decrease and their half-lives prolonged consequently. The main reason for the decrease of the evaporative loss velocity of BTEX was surfactant micelles formed and it caused the ratio of the concentration of BTEX at the liquid surface to that at the bulk liquid phase to diminish. Comparing CTMAB and Brij30 with SDBS, the evaporative loss of BTEX from static water decreased more evidently in CTMAB and Brij30 solutions. The positive relation was found between the restraining ability of a surfactant and the octanol-water partition coefficients or Henry's law constants of BTEX.