氮掺杂强化生物炭还原-络合协同固定重金属铬的机制研究

In-situ immobilization of heavy metals by biochar serve as an effective method for heavy metals-contaminated soil remediation, and the enhanced immobilization of heavy metals by modified biochar has attracted intensive attention. The key to the immobilization of heavy metals by biochar is surface functional groups. Nitrogen doping could significantly enhance the immobilization of chromium by biochar due to addition of nitrogen-containing functional groups. However, the feature of different nitrogen-containing functional groups and the mechanism of immobilization of heavy metals by nitrogen-doped biochar were currently unknown. This project is going to systemically investigate the effect of nitrogen doping on immobilization of chromium by biochar. It will provide a method to fabricate nitrogen-doped biochar for high-efficient immobilization of heavy metals. Electrochemistry and spectroscopy analytical technologies are used to characterize and analyze nitrogen-doped biochar. It will determine the quantitative characterization of electron transfer capacity and process and reveal the effects of different nitrogen-containing functional groups on reduction of chromium by biochar. We also investigate the re-absorption process of chromium (III) by of nitrogen-doped biochar to illustrate the mechanism of enhanced immobilization of chromium by biochar with nitrogen-containing functional groups. It will reveal the mechanism of enhanced immobilization of chromium by nitrogen-doped biochar with coupled reduction-complexation reaction. The results may provide theoretical foundation to develop the remediation technology of heavy metals-contaminated soil by biochar.

生物炭原位钝化技术是治理土壤重金属污染的有效措施，如何改性强化生物炭重金属钝化作用是当前研究热点。表面基团是影响生物炭钝化固定重金属的关键，氮原子掺杂改性表面基团可提高生物炭重金属还原/络合吸附效果，但含氮基团的功能和钝化重金属作用机理尚不明确。本项目以氮掺杂生物炭为对象，以铬为模式污染物，系统研究氮掺杂生物炭钝化重金属铬的强化效应，建立构建高效氮掺杂生物炭重金属钝化剂的方法；利用电化学和光谱技术，表征氮掺杂生物炭电子转移能力和过程，探明不同含氮基团对生物炭还原重金属铬的贡献，研究氮掺杂生物炭对三价铬的再吸附过程，明确含氮基团强化生物炭吸附铬的机制，阐明氮掺杂强化生物炭还原-络合固定重金属铬的耦合过程和机制，为发展生物炭重金属污染土壤修复技术提供理论基础。

本项目研究氮掺杂改性生物炭钝化/去除重金属铬的强化效应，利用电化学-光谱技术，在不同外源氮掺杂、富氮生物质自掺杂、热解温度、KOH活化等条件下，系统研究氮掺杂生物炭还原-吸附六价铬作用规律、物化特性、表面基团分布、电子转移特征等，提出了KOH活化调控氮自掺杂改性的方法，构建了基于还原-络合过程高效治理重金属六价铬的生物炭钝化剂，揭示了氮掺杂生物炭以氨基、羟基强化络合吸附和醌基-酚基介导还原协同固定/去除重金属六价铬的电子传递过程及作用机理，为生物炭在重金属污染土壤环境修复领域的应用提供支持。在此基础上，利用氮掺杂强化碳材料电子传递能力，构建高效生物电化学/光化学体系，实现废水处理过程污染物快速降解同步生物能源高效回收，拓展氮掺杂碳材料在水环境治理领域的应用。相关结果已发表SCI论文5篇，中文核心论文1篇，培养硕士研究生4名，完成预期任务。