纳米铁复合氮掺杂碳对多环芳烃污染土壤修复机理的研究

The remediation of polycyclic aromatic hydrocarbons (PAHs) contaminated soil has recently become a research focus in environment field，and Fenton oxidation is considered to be an effective way to remove PAHs pollutants due to its capability to produce hydroxyl radical. However, the main disadvantages for the traditional Fenton system are the harsh reaction condition and high cost. In our prophase work, we prepared the nitrogen-doped porous carbon (N-PC) using lignin from black liquor as the precursor, and made it clear that the fixation effects on the pollutants were due to the microstructure and the surface functional groups of N-PC material. In this project, nanoscale zerovalent iron (nZVI) will be supported on the pre-prepared N-PC carrier, and then the nZVI/N-PC/Air Fenton system will be constructed by nZVI/N-PC and the atmosphere, which can be used to realize the oxidative remediation of PAHs in soil. Moreover, the micro-morphology and structural performance will be controlled to enhance the adsorption of PAHs, and the mechanism between nZVI/N-PC/Air Fenton system and PAHs will be revealed. Meanwhile, we will analyze the changes of soil properties and the toxicities of degradation products before and after remediation in order to illustrate the effect of Fenton system on soil quality, and then evaluate the ecological risk for soil. The proposed research will provide the theoretical basis and technical support for the development of secure and efficient remediation technology for organic pollutants contaminated soil.

多环芳烃（PAHs）污染土壤的修复是环境领域研究的热点，Fenton氧化法因其能产生羟基自由基被认为是去除PAHs的有效方式，但传统Fenton体系存在反应条件苛刻、成本高等关键问题。申请人前期以制浆废液木质素为前驱体制备了氮掺杂多孔碳（N-PC）材料，明确了材料的微观结构和表面官能团对污染物的固定作用。在此基础上，本项目拟利用N-PC为载体负载纳米零价铁（nZVI），与大气中的氧气构建nZVI/N-PC/Air Fenton体系，实现对土壤中PAHs的氧化修复。通过调控nZVI/N-PC的微观形貌和结构性能，增强其对PAHs的吸附，揭示nZVI/N-PC/Air Fenton体系与PAHs的作用机制；分析修复前后土壤性质变化和降解产物毒性，阐明构建的Fenton体系对土壤质量的影响，进而评价该体系的土壤生态风险。本项目的实施将为发展安全高效的土壤有机污染物修复技术提供理论依据和技术支持。

环境中多环芳烃等持久性有机污染物和重金属离子的存在，给人类的健康带来极大的危害，探索合适的材料与方法对其进行治理势在必行。传统的处理方法存在原材料昂贵、操作繁琐、反应条件苛刻等缺点。本课题以造纸黑液中提取的木质素和松果等废弃物为前驱体，制备了腐殖酸涂覆的磁性掺氮多孔碳（HA-N-MPC）、木质素水热炭封装纳米零价铁（Fe@HC）、纳米零价铁复合磁性掺氮多孔碳（Fe-N-MPC）、氮、硫共掺杂磁性多孔碳封装纳米铁（Fe-N-S-MPC）、EDTA功能化的三维磁性掺氮多孔碳（N-MPC-EDTA）及纳米铁负载氮掺杂泡沫碳（Fe@CF-N）复合材料，将其应用于水和土壤中污染物的治理。实验结果表明：制备的材料具有比表面积大、官能团丰富、反应活性位点多等优点，可有效固定并分散金属纳米粒子，使材料呈现出优异的吸附和催化性能。将复合材料与H2O2、O2、PMS等氧化剂构建多种新型类Fenton体系，实现对多环芳烃污染物荧蒽、1-萘酚及苯酚等的催化降解，降解产物为低毒或无毒的小分子物质；基于材料的多孔性、大比表面积和丰富的活性位点，对重金属离子Cr(VI)和Cd(II)进行吸附，最大吸附容量分别为130.5 mg ∙ g-1和43.68 mg ∙ g-1，部分毒性较大的Cr(VI)被还原为毒性较小的Cr(III)。通过对修复前后土壤理化性质的研究和植物毒性实验，阐明了构建的类Fenton体系对土壤质量的影响，进而评价该类Fenton体系的土壤生态风险。本研究为开发绿色、高效、经济的环境污染修复技术提供了理论依据和技术支持。