生物炭在有机污染物降解体系中反应活性的结构溯源

生物炭在去除水体中有机污染物方面表现了巨大潜力。前期研究指出，生物炭中的持久性自由基（EPFRs）对有机污染物的降解起到了非常重要的作用。申请人在前期实验中观察到，生物炭中的EPFRs不能解释所有的有机物降解现象，对其他过程或机制的忽略可能导致对生物炭功能理解的误判，对有机污染物环境行为认识的偏差。本项目围绕生物炭与有机污染物相互作用机制展开更加深入的研究，在系统理解前期研究的基础上，对生物炭体系中有机污染物的降解机制进行系统的识别，包括：通过分离的生物炭上清液降解实验论证生物炭溶出DOM的作用；通过化学改性调控生物炭性质理解其氧化还原能力与有机污染物降解的关联；通过制备条件改变生物炭稠环度特征，探明生物炭导电能力的贡献。经过一系列对照、屏蔽实验，重点对各种机制的贡献和结构特征进行识别。本研究将对生物炭的性质和功能进行更加深入的理解，是生物炭功能开发、环境效应评价的重要理论基础。

Biochars have shown their promising application potential in organic pollutant removal from water. Previous studies mostly emphasized the adsorptive removal. Our earlier studies discovered significant degradation of organic pollutants in biochar sorption systems, and emphasized that the environmentally persistent free radicals (EPFRs) detected on biochar particles played an important role in organic pollutant degradation. In the applicant’s preliminary experiment, EPFRs in biochars could not fully explain the degradation of organic contaminants. If the degradation mechanisms of organic contaminants in biochar systems could not be clarified, the environmental roles and functions of biochars will not be correctly understood. Importantly, a wrong conclusion regarding organic contaminant behavior as affected by large-scale biochar application may be reached. This work is designed to extensively investigate the interaction mechanisms between biochars and organic contaminants, specifically the degradation mechanisms of organic contaminants mediated by biochars. Based on the previous studies, different techniques will be applied to identify the contribution of individual mechanisms, including the role of EPFRs, the promoted degradation by dissolved organic matter from biochars, the redox and electron-conductivity properties of biochars. Briefly, the supernatant of biochars will be separated and the degradation of organic contaminants will be investigated in the supernatant. This experiment will be able to reveal the role of dissolved organic matter from biochars in organic contaminant degradation. Biochars will be chemically modified in order to adjust their oxidative or reductive properties. The role of biochar redox properties in organic contaminant degradation will be discussed. The pyrolysis condition will determine the aromatic condensation of biochar structures. Comparing the degradation of organic contaminants in biochars of different condensation will provide important information to understand the role of biochar electron-conductivity. Generally, different type of experiments will be conducted to exclude possible pathways of organic contaminant degradation, so that the controlling mechanisms could be identified. Importantly, the different degradation pathways in relation to biochar properties will be revealed. This work will enrich our understanding on biochar properties and functions. As the same time, the results of this work will provide fundamental support for the research on discovering new applications and evaluating environmental roles of biochars.