有机分子混合体系中纳米碳管的分散机制

With the ever increasing production and application, CNTs will inevitably be released into the environment, thus their environmental behavior and ecological risk are of great concern. CNTs are generally prone to aggregation, which should facilitate their removal from the aqueous phase; however, natural organic molecule mixtures have been reported to be effective dispersing agents for CNTs. Therefore, in real environment, where natural organic molecule mixtures are omnipresent, CNTs will be effectively dispersed by natural organic molecule mixtures, and in turn, will affect the fate and transport, health and environmental risks of both CNTs and any associated organic pollutants. Natural organic molecule mixtures contain several thousands to even millions of chemical compounds. The structures, components, and properties of different natural organic molecule mixtures are greatly various and diverse. How to describe the heterogeneous properties of natural organic molecule mixtures? How to understand the difference of CNTs dispersion mechanism between the natural organic molecule mixtures and the sole dispersion agent system? These questions are still unclear, leading to the great uncertainty for predicting the dispersion, transportation and risks of CNTs. In this study, the characteristics of natural organic molecule mixtures will be systematically described by various technologies, including exclusion chromatography, nuclear magnetic resonance, pyrolysis-gas chromatography/mass spectrometry and three-dimensional fluorescence spectroscopy. Based on these characteristics, the component diversity of natural organic molecule mixtures could be evaluated by the Shannon-Weiner Index. In binary organic chemicals system, the competitive and complementary adsorption of two organic chemicals with different properties on CNTs will be investigated and the combined dispersion mechanism of binary organic chemicals for CNTs will be explored in detail. Based on the above results, the dispersion of CNTs in organic molecule mixtures system will be quantified and the dominant dispersion mechanism will be identified. The core goal is to establish the relationship between component diversity of natural organic molecule mixtures and dispersion of CNTs. This work will supply a fundamental and useful theory and method for environmental behavior and risk assessment of carbon-based nanomaterials.

纳米碳管（CNTs）的环境行为和风险很大程度上受其分散状态影响，天然有机分子混合体系对CNTs在环境中的分散起控制性作用。然而，该混合体系与单一分散剂体系相比，分散CNTs的机制上有什么差别？从CNTs分散的角度看，如何描述有机分子混合体系的非均匀属性？这些问题都未解决，使得对复杂混合体系中CNTs分散、迁移和风险的预测有诸多不确定性。本研究拟通过多种技术手段对有机分子混合体系中各组分特征进行系统表征，利用统计学参数对体系的组分多样性进行描述；在二元有机分子体系中考察有机分子的补充吸附和竞争吸附行为，并对各有机分子对CNTs的复合分散机制进行细节上的探究；在此基础上，定量有机分子混合体系中CNTs的分散，识别主导分散机制，建立有机分子混合体系的组分多样性与CNTs分散特征的关联。本研究将为碳基纳米材料的环境行为预测和风险评价建立理论和方法学储备。

纳米碳管（CNTs）的环境行为和风险很大程度上受其分散状态的控制。环境中普遍存在的天然有机质是控制CNTs分散的主要环境介质。环境地球化学过程中形成的天然有机质在性质上存在很大的差异，包括极性、化学结构、分子量等。不同性质的天然有机质在CNTs上的吸附机理及其分散CNTs的能力差异很大，天然有机质中不同性质组分间相互作用也导致CNTs分散行为更加复杂。理解天然有机分子混合体系组分多样性与CNTs分散特征之间的关联是认识和控制CNTs及其所吸附污染物的行为和风险的关键环节。.经过四年的持续研究，基本上实现了预期的科研目标，并在此基础上，针对发现的新问题，将研究内容进行了有效的扩展。本项目主要研究内容包括：天然有机分子混合体系性质的多元描述；有机分子二元体系中CNTs的分散特征；有机分子多元体系中CNTs的分散特征；分散态CNTs对有机污染物的吸附。基于以上研究内容，取得的主要研究结果包括：.1、获得了天然有机分子混合体系组分、结构的多样性指数（Shannon-Weiner指数）；.2、发现了不同性质有机分子混合体系对CNTs的协同分散效应，提出了有机小分子在CNTs分散中的“启动机制”；.3、发现天然有机分子混合体系组分、结构多样性与CNTs分散之间的正相关性，系统阐述了天然有机质的非均质性对CNTs分散的关键作用；.4、发现分散态CNTs对有机污染物较高的吸附能力来自于CNTs额外暴露的表面积及污染物在分散剂胶束中的增溶分配。.在本项目的支持下，研究团队主编出版学术专著1部（50万字），发表SCI收录期刊论文9篇，EI收录期刊论文5篇，中文核心期刊论文4篇，授权发明专利1项。以上研究结果为碳基纳米材料的环境行为预测和风险评价建立了数据和方法学储备。