天然胶体对水沙介质中纳米材料与新兴有机污染物共迁移行为的作用

Understanding the cotransport behaviors of nanoparticles and emerging organic contaminants in porous media has great significance on the contamination control, safe drinking water protection, and the sustainable utilization of soil and groundwater. After released into subsurface, nanoparticles would interact with emerging organic contaminants, thus affect their cotransport behaviors in porous media. The ubiquitous presence of natural colloids such as natural organic matter (i.e. humic acid), clay particles, and microbe especially bacteria in natural environment would affect the interaction of nanoparticles with emerging organic contaminants and thus influence their cotransport behaviors in porous media. However, the cotransport behaviors of nanoparticles and emerging organic contaminants have not been well explored. Moreover, the effects of natural colloids on the cotransport behaviors of nanoparticles and emerging organic contaminants have never been examined. The lack of this knowledge will definitely limit our understanding of the fate of emerging organic contaminants and nanoparticles in subsurface. Thus, the objective of this study is to fill this gap by fully examination of cotransport and deposition kinetics of nanoparticles and emerging contaminants. The influence of natural colloids including natural organic matter, clay particles and bacteria on cotransport and fate of nanoparticles and emerging organic contaminants in porous media will be also investigated. Moreover, the cotransport and retention of nanoparticles together with emerging organic contaminants in real soils will also be investigated. The results of study will provide new efforts not only for the safe utilization of nanoparticles and estimation the fate of emerging organic contaminants in natural environment, but also for the successfully implementation of nanotechnique to remediate the contaminated soil and groundwater, and thus ensure the sustainable utilization of soil and groundwater.

新兴有机污染物与纳米材料的水沙多介质环境行为是水沙污染控制与修复的重要研究课题。进入水沙环境介质的纳米材料会与新兴有机污染物发生相互作用，进而影响其自身及新兴有机污染物在水沙环境介质中的空间分布。水沙介质中普遍存在的天然胶体如有机质、矿物颗粒、微生物等会影响纳米材料与新兴有机污染物的相互作用，从而影响两者的共迁移行为。然而，并未有研究报道纳米材料与新兴有机物的共迁移行为及天然胶体对共迁移行为的作用机制。本项目拟研究纳米材料与典型新兴有机污染物在水沙环境介质中的共迁移行为及其作用机制，并进一步考察有机质、矿物颗粒、微生物等天然胶体对纳米材料与新兴有机污染物共迁移行为的影响，初步搞清两者在典型真实水沙介质中的共迁移行为。研究成果将为纳米材料的安全应用及新兴有机污染物的水沙环境风险评估提供理论指导与技术支持，以保障水沙环境的健康与可持续利用。

明确纳米颗粒与有机污染物在环境介质中的行为是控制土壤-地下水污染及保障其可持续利用的关键。研究考察了典型纳/微米材料塑料颗粒与有机污染物相互作用及共迁移行为研究，发现纳/微米塑料颗粒会与有机污染物发生相互作用。吸附至塑料颗粒表面的有机物通过改变塑料颗粒的表面性质与粒径，进而改变塑料颗粒与介质之间的相互作用，从而影响塑料颗粒的迁移行为。塑料颗粒则会充当有机物的迁移载体，影响有机污染物的迁移行为。考察了天然胶体对纳/微塑料颗粒与有机污染物迁移行为的影响，发现天然有机质会吸附至塑料颗粒的表面抑制塑料颗粒的团聚，通过空间位阻作用力，抑制塑料颗粒的沉积促进塑料颗粒的迁移。探索了环境介质中纳/微塑料颗粒迁移的阻控技术，发现生物膜与生物炭对塑料颗粒具有较强的吸附性能，从而抑制塑料颗粒的迁移。研究中同时考察了纳米材料对生物胶体迁移行为的影响，发现高离子强度条件下，纳/微塑料颗粒通过空间位阻作用力、竞争吸附位点、或协同迁移等一种或多种机制促进细菌的迁移行为。发现负电荷树枝状聚合物会增加细菌和介质间的电性斥力并且通过与细菌竞争石英砂表面的沉降位点，以及空间位阻作用力促进细菌迁移，而正电荷树枝状聚合物会抑制细菌和介质间的电性斥力并且通过提供额外沉降位点抑制细菌迁移。研究发现氧化石墨烯在低团聚状态下会充当细菌迁移的载体促进细菌迁移，而当其与细菌形成大团聚体时则会抑制细菌的迁移。不同电性的蛋白质对细菌迁移行为存在不同的作用，负电性蛋白质会通过空间位阻作用力以及竞争吸附位点促进细菌的迁移，而正电性蛋白质则通过改变细菌与介质的表面性质与细菌的大小，以及增加额外的沉降位点抑制细菌的迁移。为了促进纳米零价铁在多孔介质中的迁移能力，采用了膨润土与海藻酸钠对纳米零价铁进行修饰以促进其迁移性能，并考察了改性的零价铁对六价铬的去除能力，发现改性后的纳米零价铁仍具有很高的价铬的去除性能。并开展了功能性纳米材料对水体中重金属去除与微生物灭活方面的应用研发工作。研究成果对于明确纳关键带中纳米材料的迁移规律及其在水质净化方面的应用具有重要的指导意义。