【作者】 李金花；

【导师】 周保学；

【作者基本信息】 上海交通大学 ， 环境科学， 2008， 博士

【摘要】 复合化学污染对有机污染物在土壤/沉积物上的环境吸附行为的影响,已经成为环境化学领域关注的热点。越来越多的无机和有机污染物进入环境,使得绝对意义上的单一环境污染已经不存在。共存污染物之间存在的复杂交互作用,使得复合化学污染的环境行为及其影响已经变得越来越明显,一些污染物特别是难降解的有毒有害有机污染物(包括持久性有机污染物、环境激素等)的迁移转化途径及生态效应也变得越来越复杂,甚至污染行为加重。而有关复合化学污染对难降解的有毒有害有机污染物的环境吸附行为及其影响机制、控制方法,则缺乏深入、系统的研究。本文以三种典型的有毒有机污染物,环境激素物质双酚A、多环芳烃萘和可离子化的对硝基苯酚为代表,研究了重金属、表面活性剂等复合化学污染对其环境吸附行为的影响及其作用规律,表明复合化学污染能明显影响有毒有机污染物的环境吸附/解吸等环境迁移行为:(1)重金属、表面活性剂等污染物以及环境因素(pH值,离子强度)等能够影响双酚A在沉积物上的静态吸附行为。单一重金属Pb2+或Cd2+均增强了双酚A在沉积物上的吸附;阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)和氯代十六烷基吡啶(CPC)增强了双酚A在沉积物上的吸附,而阴离子表面活性剂十二烷基苯磺酸钠(SDBS)则轻微的抑制了双酚A在沉积物上的吸附;阳离子复合表面活性剂对双酚A在沉积物上的吸附具有协同效应,其促进作用强于同浓度下CTAB或CPC单独存在时的吸附促进作用;而阳离子表面活性剂和重金属的复合体系也增大了双酚A的吸附,并且随着表面活性剂浓度的增大,重金属的吸附促进作用相对于表面活性剂的吸附促进作用而言,影响力逐渐减弱,此时,主要表现为表面活性剂的吸附促进作用。pH值的降低和离子强度增大,双酚A的吸附量也随之增大。(2)重金属、表面活性剂等污染物以及环境因素pH值,离子强度等也能够影响双酚A在土壤上的动态吸附/解吸行为。离子强度和重金属均促进了双酚A在土壤上的吸附,并且对解吸有抑制作用;阳离子表面活性剂CTAB和CPC对双酚A在土壤上的吸附有促进作用,存在明显的“拖尾”现象,相应的解吸量也增加。因此,在对被有机污染物污染的土壤进行修复的过程中,有机物对地下水可能造成的影响必须要予以考虑。(3)小分子有机酸在低浓度时,对萘的吸附影响不显著,而高浓度时,对萘在沉积物上的吸附有较为明显的抑制作用,并且随着有机酸浓度的增大和碳链的增长抑制作用变得越来越明显。这主要是有机酸对萘的溶解和吸附竞争作用,以及有机酸对沉积物结构影响等几种作用竞争的结果。(4)环境激素类物质双酚A、2, 4-二氯苯酚、2, 4-滴对对硝基苯酚在沉积物上的吸附有不同程度的竞争作用。2, 4-二氯苯酚对其的吸附竞争作用强于双酚A、2, 4-滴。竞争能力的大小与有机化合物的吸附能力的大小,以及苯环上的取代官能团不同有关。吸附等温线的非线性程度越强,其竞争能力越强;而吸附能力较弱以及在实验条件下可离子化的有机污染物对对硝基苯酚的吸附竞争能力则较弱。更多还原

【Abstract】 Combind pollution has become one of the important directions of environmental chemistry at present. Sorption of organic pollutants by soils/sediments plays an important role in their transport, fate and bioavailability in natural environment. In response to the serious combind pollution of soils and groundwater, it is interested to understand and evaluate the sorption behaviors of organic pollutants on soils/sediments, and to control the sorption behaviors. In this dissertation, the sorption behaviors and mechanisms of organic pollutants by combind pollution onto soils/sediments were investigated detailedly. The main conclusions of this dissertation are:(1)The effects of different heavy metals (Cd2+ Pb2+), cationic surfactants cetyltrimethylammonium bromide (CTAB), anionic surfactant sodium dodecylbenzenesulfonate (SDBS)) and the chemistry of the solution (pH and ionic strength) on the sorption of bisphenol A (BPA) to sediment were studied. Results showed that the presence of Cd2+ and Pb2+ caused a significant increase on the sorption of BPA to sediment. The effect of surfactants on the adsorption of BPA onto sediment was found to strongly depend on the type of the surfactants. The presence of CTAB promoted BPA sorption and the amount of BPA adsorbed onto sediments increased linearly with concentration of CTAB. In contrast, the presence of anionic surfactant (SDBS) caused a slight reduction on the sorption of BPA. In complex system, the compounding effect of heavy metals and surfactants on BPA sorption was significant. Moreover, with the increase of the surfactant concentration, the increase on BPA sorption caused by surfactants was predominat than that of heavy metals. It was also found that the sorption behavior of BPA was affected by solution pH and ionic strength. The larger amount of BPA was absorbed with higher ionic strength and lower pH.(2)The effects of different heavy metals (Cd2+, Pb2+), surfactants ((CTAB), (CPC)) and the ionic strength (Ca2+, NH4+) on sorption and desorption of BPA were studied using soil column experiment. Results showed that the presence of heavy metals and cationic surfactants caused a significant increase on the BPA sorption. In addition, a clear difference between these sorption curves is the“tailing”in the presence of CTAB and CPC (slow approach to Ce/C0=1), that is characteristics of nonequilibrium sorption during BPA transport. It was also found that the larger amount of BPA was absorbed with higher ionic strength. The cationic surfactants enhanced the desorption ability of BPA form the soil. However, the Cd2+, Pb2+ and Ca2+, NH4+ decrease the sorption of BPA. The results provided a better understanding of BPA behavior in environment and facilitated more accurate assessment of its ecological risk and identification of appropriate management strategies.(3)The sorption behavior of naphthalene in the presence of dissolved organic acid was studied. The presence of dissolved organic acids at lower concentrations had only a little effect on naphthalene sorption. However, when the concentration exceeds a certain concentration, a significant inhibition was observed. Moreover, the inhibition enhanced with the increasing concentrations of dissolved organic acids. In addition, the change of structure of sediment is an important factor that can affect the naphthalene sorption. This suggests the change of solubility of naphthalene and the change of structure of sediment in dissolved organic acids solution both exert effect on naphthalene sorption。(4)Sorption behavior of four chemicals BPA, 2, 4-dicholrophenoxyacetic acid (2, 4-D), 2, 4-dichlorophenol (2, 4-DCP) and p-nitrophenol (PNP) to sediment was investigated by means of batch sorption experiments. Results showed that all the isotherms for each single chemical were in good agreement with Freundlich equation. The influence of BPA, 2, 4-D and 2, 4-DCP as cosolutes on the sorption of PNP as target solute was studied by determining the single isotherm of PNP. Little or no competitive phenomenon was observed in the presence of BPA and 2, 4-D. In contrast, the competitive inhibition occured when 2, 4-DCP were introduced to the solution. In addition, the competitive power enhanced with the increasing of cosolute concentration. The competitive degree depends on the hydrophobicity, concentration and the functional group of cosolute, and can be interpreted by dual-mode model.更多还原