【作者】 宫晓飞；

【导师】 曹晓燕；

【作者基本信息】 中国海洋大学 ， 海洋化学， 2011， 硕士

【摘要】 大量的表面活性剂和有机污染物通过工业废水及生活污水的排放,农业径流等途径进入水体,由此造成水体的复合污染。DDT是世界公认的环境优先控制污染物,也是典型的持久性污染物。虽然我国于1983年禁止了DDT的生产及在农田中的使用,但由于它具有高残留、化学性质稳定和生物累积性等特点,至今仍大量的残留在环境中。而非离子表面活性剂在产量上是仅次于阴离子表面活性剂的重要表面活性剂,有良好的扩散、乳化和润湿等作用,广泛应用在食品、化工、洗涤、医药等工业中,排入海洋中的非离子表面活性剂会改变沉积物/水体的物理化学性质,从而对有机污染物的迁移转化产生影响。本论文以人工海水溶液为介质,以失水山梨醇聚氧乙烯（20）醚月桂酸酯（Tween20）和DDT为研究对象,探讨了两种污染物共存时在沉积物上的热力学行为和吸附动力学行为,并就吸附影响因素包括温度,盐度、沉积物性质对吸附的影响进行了研究,借用红外分析手段探讨DDT吸附机理。结论如下:（1）动力学研究表明,伪二级吸附速率方程可以很好的描述Tween20在沉积物上的吸附动力学过程,Tween20吸附速率随着其初始浓度的减小和温度的升高而增大。沉积物对Tween20的吸附活化能为17.75 kJ·mol^-1,吸附过程是以物理吸附为主。DDT在沉积物上的吸附动力学曲线符合伪二级吸附速率方程,在实验浓度范围内,Tween20的加入能够加快DDT在沉积物上的吸附速率。（2）热力学研究表明,Freundlich等温式可以很好的描述DDT在沉积物上的吸附热力学过程;在Tween20和DDT的共存体系中,Tween20 (C0: 5 mg·L^-1, 10 mg·L^-1, 30 mg·L^-1, 80 mg·L^-1)的存在使DDT(C0: 0.1411 mg·L^-1～1.129 mg·L^-1)在沉积物上的平衡吸附量增加,其吸附等温线趋于线性;当Tween20初始浓度为160 mg L^-1时,Tween20在溶液中形成胶束而对DDT产生增溶作用导致沉积物对DDT的吸附量较单一体系少。（3）吸附因素研究表明,在单一体系和复合体系中,随着温度的降低、溶液盐度的增加和粒径的减小,沉积物对DDT的吸附量均增加。此外DDT在不同处理方式的沉积物上的吸附规律如下:KF（HCl处理样）> KF（H2O处理样） > KF（H2O2处理样）;而加入30 mg·L^-1 Tween20后,在HCl处理的沉积物上,DDT的吸附量较未加Tween20的单一体系吸附量少;而在H2O2处理的沉积物上,DDT的吸附量则较未加Tween20的单一体系吸附量大。（4）热力学研究表明,在281K-308K范围,无论是单一体系还是复合体系,DDT在沉积物上的的吸附热力学函数均为ΔH（?）<0,ΔG（?）<0,ΔS（?）>0,即该吸附过程是一个放热、熵增的自发的物理吸附过程。Tween20的存在使p,p’-DDT和o,p’-DDT在吸附过程中的|ΔG（?）|和|ΔH（?）|的值更高,ΔS（?）更小。（5）对沉积物、DDT-沉积物作用物进行红外表征,对比谱图发现DDT在沉积物表面吸附时,可以和沉积物上的羰基、羟基、酚羟基发生了氢键作用。更多还原

【Abstract】 Surfactants and other organic pollutants are transported into water system through the release of industrial and domestic wastewater, which results in an combined pollution. DDT is a kind of typical persistent organic pollutant. Although its use in agriculture has been banned in China in 1983, unfortunately, it,s still widely distributed in environment because of its persistence, chemical stability and bioaccumulation. Nonionic surfactants are used wildly in industries of food, chemical, and washing due to the characteristics of dispersion, emulsification and wetting effects. The existing of non-ionic surfactants in the ocean can change the physicochemical propertis of sediment/water interface, thus it has an effect upon the migration of organic pollutants.In this thesis, the sorption kinetics and thermodynamics of Tween20 and/or DDT were studied in the system of sediment-artificial seawater. Furthermore, the effects of temperature, salinity and the properties of sediment were also investigated. The main results are as follows:（1） The sorption kinetic process of Tween20 and/or DDT on the sediments was proven to follow the pesudo-second-order kinetic rate equation. The sorption rates were favorably influenced by the decreasing initial Tween20 concentration and increasing temperature. The sorption activation energy of Tween20 was 17.75 kJ·mol^-1, which indicated that the sorption process was mainly a physics one. Tween20 could accelerate the sorption rate of DDT onto sediment in the experimental concentrations.（2） The sorption isotherms of DDT on sediment could be described by the Freundlich isotherm. The results showed that Tween20 with the initial concentrations of 5, 10, 30 and 80mg·L^-1 could enhance the sorption capacity of DDT (C0: 0.1411 mg·L^-1～1.129 mg·L^-1) and linearized the isotherms of DDT onto sediment. When the initial concentration of Tween20 was 160 mg·L^-1, the formation of micelles of Tween20 enhanced the aqueous-phase concentration of the DDT thereby decreasing its sorption on sediment compared to the single system.（3） Studies on impact factors of the sorption indicated that sediment enhanced its capacity to absorb DDT with decreasing temperature, increasing salinity and decreasing sediment particle sizes in both single and combined systems. For DDT sorption on the sediments with different treatments, KF（HCl treatment）> KF（H2O treatment） > KF（H2O2 treatment）. In the presence of 30 mg·L-1 Tween20, the sorption capacity of DDT onto HCl treatment sediment was lower than that in the single system. While for the H2O2 treatment sediment, the sorption capacity of DDT was higher than that in the single system.（4） Estimation of thermodynamic parameters indicated that the sorption behavior of DDT was a spontaneous, exothermic and entropy-increasing physical one. The existence of Tween20 caused the∣ΔG（?）∣and∣ΔH（?）∣values higher andΔS（?） value smaller during the DDT sorption process.（5） The sediment and DDT-sediment complexes were characterized by FTIR spectra. It was confirmed that the sorption was resulted form hydrogen bonds formation between DDT molecules and the C=O, phenolic and alcoholic O–H groups of sediment.更多还原