矿物对土壤吸附疏水性有机污染物的调控作用

Inorganic minerals can be intimately associated with a large portion of NOM in soils, and then play an important role in the sorption behavior of HOCs. Recent studies show that the chemical nature of NOM itself does not fully explain or predict the sorption behavior of HOCs. Therefore, this project aims to explore the role of NOM structural chemistry and physical morphology under the interaction with minerals, and will therefore determine the sorption behavior of HOCs. The specific objects are as follows. To meet this objective, thermology, thermodynamics and several novel analysis experiments will be carried out to gain quantitative, semiquantitative and the submicron-level image insight into the chemical nature and physical conformation of HA by using organo-mineral complexes. Batch equilibration sorption studies will be used to study HOCs to constructed organo-mineral complexes and source HAs under different solution conditions, which can provide us with the non-ideal sorption characteristics and the effects of solution conditions. In addition, STXM-NEXAFS, a novel technique, which enable one to indentify and fingerprint the fine structures of NOM and directly image micrometer sized environmental samples with nanometer spatial resolution, will be employed to map phenanthrene as model compound for HOCs on HA-mineral complexes. The combination of chemical information and physical morphology will determine the regulating role of soil minerals in the transport and retention of HOCs. The result will show scientific insights into the determination the HOCs sorption mechanisms and strategies for pollutants remediation.

土壤中无机矿物组分会与NOM结合，从而影响HOCs的吸附行为。通过阐明NOM与矿物作用过程中理化特性的变化及其对HOCs吸附行为的影响，为解决NOM的化学性质本身不能完全解释HOCs吸附行为这一难题提供思路。通过热学、热力学实验与先进分析手段相结合，探索HA与矿物结合过程中化学结构特性和纳米尺度微形貌特征；通过传统批量吸附实验，以菲为代表性HOCs，从非理想吸附行为以及溶液化学条件对吸附的影响两方面证实矿物通过改变HA的理化特性，从而影响着HOCs的吸附；通过扫描透射X射线显微镜（STXM）和高分辨近边吸收精细结构谱（NEXAFS）对吸附了HOCs的模拟复合体进行分析，掌握HOCs在吸附剂中空间分布的化学信息和纳米微形貌特征，为阐明矿物对HOCs吸附的调控作用提供直接证据。本研究为HOCs在土壤中吸附机制的解析，以及污染场地的修复策略提供科学参考。

本项目拟通过阐明NOM与矿物作用过程中理化特性的变化及其对HOCs吸附行为的影响，为解决NOM的化学性质本身不能完全解释HOCs吸附行为这一难题提供思路。项目采用FTIR、XRD、DSC等表征手段，研究了以HA为代表的NOM在与不同矿物（蒙脱土、高岭土和针铁矿）复合前后的形态结构变化，发现HA通过与不同类型的矿物复合后，其玻璃化转变温度Tg发生了明显的改变，说明HA的结构和组分发生了变化，这也必然导致了HA-矿物复合体对HOCs的吸附性能发生了相应的改变。通过传统批量吸附实验，以菲为代表性HOCs，改变溶液化学条件，探讨了矿物对菲吸附的调控行为和机制，结果发现离子强度、离子种类、pH以及温度对菲在不同HA-矿物复合体上吸附的影响显著，并且体现出明显的矿物调控机制的差异，为受污染HOCs土壤的修复策略提供基础数据。此外，对受HOCs（菲）污染土壤的化学氧化修复进行了初步研究，阐明了超声波辅助的情况下，过硫酸钠对土壤中菲的氧化降解效率，为实际情况下受HOCs污染的土壤/沉积物的原位修复提供直接参考。