【作者】 杨坤；

【导师】 朱利中；

【作者基本信息】 浙江大学 ， 环境科学， 2004， 博士

【摘要】 土壤/沉积物对有机污染物的吸附是影响其在环境中迁移转化、归宿和生物生态效应的主要因素之一。为控制和修复土壤及地下水有机污染，需要了解和调控有机污染物在水饱和土壤/沉积物上的吸附行为。环境中共存的表面活性剂，会显著影响有机污染物在土壤/沉积物上的吸附。因此，可以利用表面活性剂调控其吸附行为，达到控制和增效修复土壤及地下水有机污染的目的。本文研究了有机物、表面活性剂和混合表面活性剂在土壤/沉积物上的吸附行为、规律及机理，探讨了混合表面活性剂增强调控有机物在土壤/沉积物上吸附行为的作用机制。论文取得了以下一些价值的研究结果： (1) 发现在所研究的有机物范围内，它们在土壤/沉积物上的分配系数和表面吸附系数都与土壤/沉积物有机碳含量呈显著线性正相关，与有机物溶解度呈负相关，而与比表面积、粘土含量等无关。明确了有机质是有机物在土壤/沉积物上非线性吸附的主导源。建立了利用土壤/沉积物有机碳含量和有机物溶解度两个参数预测估算有机物在土壤/沉积物上非线性吸附的模型。 (2) 建立了多元线性统计回归分析土壤/沉积物组成吸附非离子表面活性剂能力的方法，探明了土壤/沉积物对非离子表面活性剂的吸附由有机质含量、粘土矿物含量及类型共同决定。土壤/沉积物各成份对Triton X-100的吸附能力大小顺序为：蒙脱石＞有机碳＞伊利石＞1.4nm矿物＞＞高岭石。 (3) 探明SDBS在土壤/沉积物粘土矿物上损失的主要原因为SDBS和钙镁离子间的沉淀，其机理为SDBS的钠离子将粘土中的钙离子通过阳离子交换释放到溶液中，并与SDBS在溶液中产生沉淀。 (4) 发现阴-非混合表面活性剂能降低表面活性剂在土壤粘土上的吸附等损失，并增强洗脱土壤有机污染。Triton X-100和SDBS质量比为1：9时，表面活性剂在土壤上的吸附损失最少，对污染土壤中菲的洗脱效率最高。溶液中混合胶束阻止类胶束态的形成、阻止SDBS和土壤表面间的静电吸引、阻止Triton X-100和土壤表面间的氢键、促进SDBS和钙离子形成沉淀产物的再溶解，是降低以及最小化Triton X-100和SDBS损失的主要机理。建立了利用表面活性剂的损失量和临界胶束浓度计算其对土壤中有机污染临界洗脱浓度的模型。 (5) 提出了用阳-非混合表面活性剂增强土壤/沉积物对有机污染物吸附固定的方法。单一CPC或Triton X-100能将沉积物吸附硝基苯的能力分别提高50倍和9.1倍，cPc和Tritonx一100混合表面活性剂溶液则能将沉积物吸附硝基苯的能力提高70倍。阳一非混合表面活性剂提高有机物在土壤/沉积物上吸附的机理为阳离子表面活性剂和非离子表面活性剂在土壤/沉积物上的共同吸附提高了沉积物的有机碳含量。更多还原

【Abstract】 Sorption of organic pollutants by soilsk/sediments plays an important role in their transport, fate and bioavailability in natural environment. In response to the serious 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. Surfactants, in natural environment, effect the sorption behaviors of organic pollutants onto soils/sediments, which offers a potential way to protect soils/ground-water or to remediate the polluted soils/groundwater. In this dissertation, the sorption behaviors and mechanisms of organic pollutants and surfactants onto soils/sediments were investigated; the control methods on the sorption of surfactants and even organic pollutants onto soils/sediments by mixed surfactants were disscussed detailedly. The main original conclusions of this dissertation are:(1) It is observed that soil/sediment organic matter is response to the sorption nonlinearity of nonpolar or polar organic pollutants on soils/sediments. Partition coefficients and adsorption coefficients for organic pollutants are both linear with the soil/sediment organic carbon content, rather than the clay content and the surface area. The partition coefficients and adsorption coefficients normalized by organic carbon content are relatively constant, and linear with the solubilities of organic pollutants by a negative way. Then, a model was developed to calculate the nonlinear sorption of organic pollutants on soils/sediments by tow parameters (the soil/sediment organic carbon content and the water solubility of organic pollutants) only.(2) The importance of soil/sediment organic matters and clay minerals on their sorption of Triton X-100 was investigated by the multi-component statistic analysis. It is indicated that sorption of Triton X-100 on soils or sediments is the combined contribution of soil/sediment organic matters and clay minerals, which depended on both the contents of soil/sediment organic matters and the types and contents of clay minerals. The sorption power of soil/sediment composition for Triton X-100 conforms to an order of montmorillonite > organic carbon > illite >1.4nm minerals (vermiculite + chlorite + 1.4 nm intergrade mineral)?kaolinite.(3) Losses of anionic surfactant on soils/sediments is attribute to the precipitation between anionic surfactanta ions and soil/sediment divalent cations. The cation exchange between soil/sediment and Na+ leading to the release of Ca2+ and subsequent precipitation of anionic surfactants (SDBS) in solutions, are the mechanisms of precipitation. Precipitation exists in solution but not happens in the interlayer of clay such as montmorillonite.(4) Desorption of phenanthrene from soil to water are more efficiency by mixed Triton X-100 and SDBS solutions than by the individual surfactants. For example, theminimizing losses of surfactants at the mass ratio 1:9 of Triton X-100 and SDBS, the highest desorption efficiency of phenanthrene from soil is observed. The enhanced desorption by mixed anionic-nonionic surfactants is primarily due to the minimizing losses of surfactants. Mixed micelle formation, which inhibits the adsorption of Triton X-100 on soil and the precipitation of SDBS with Ca2+, is responsible for the minimizing losses of Triton X-100 and SDBS in their mixed systems. A model is suggested to calculate the critical washing concentrations from the losses and the critical micelle concentrations of surfactants.(5) The sorption of organic pollutants onto soils/sediments is enhanced by the co-existed nonionic or cationic surfactant, and will be significantly enhanced by their mixtures. The sorption capability of sediment for nitrobenzene is enhanced 50, 9.1 and 70 times by CPC, Triton X-100 and their mixtures, respectively. The organic matter content enhanced by the cosorption of nonionic and cationic surfactant, is response to the enhanced sorption capability of soil/sediment.更多还原