磁性石墨烯基复合吸附剂对脱硫浆液中Hg2+还原控制的研究

The proposal is focusing on the issues of Hg2+ reduction and re-emission of Hg0 in the gypsum slurry, which would result in serious secondary pollutions. Although Hg2+ would be stabilized by addition of additives and/or chelants thus inhibiting its reduction, Hg would be enriched in the gypsum, which cause serious potential risk for gypsum utilization. Herein, we propose to develop an regenerate adsorbent based on graphene for Hg2+ absorption in gypsum slurry. For one thing, the adsorbents would have high selective performance and adsorption efficiency for Hg2+. And another, the adsorbents would be easily segregated via magnetic separation from the gypsum slurry. Finally the adsorbents could be regenerated by chemical methods treatment. We aim to fundamentally control Hg2+ re-emission and avoid enrichment of Hg in gypsum. The project is supported by multidisciplinary of combustion theory, environmental science, functional material science. It is supposed to find the pathways of Hg2+ reduction in gypsum to slurry by simulating the flue gas desulfurization system. We would also reveal the adsorption mechanisms of Hg2+ on functionalized grapheme oxides and to establish the kinetic modal for Hg2+ adsorption. Moreover, by decorating Ag nanoparticles on the sheet of magnetic graphene oxide to achieve the goal for the combination adsorption of Hg2+ and Hg0. For adsorbents regeneration process, we would like to reveal the optimal chemical process for adsorbent regeneration and evaluate the possibility of the volume production of adsorbents. The work would provide a theoretical basis and technical support for simutaneous Hg removal by WFGD, and also expand the utilization of fuctionalzed graphene material in the field of energy and environment protection.

本项目针对燃煤电厂WFGD脱硫石膏浆液中Hg2+还原再释放造成环境二次污染，及螯合剂固Hg后在脱硫石膏中富集的问题，交叉融汇燃烧学、环境科学、及功能材料学等学科基础理论，开发可再生磁性石墨烯基复合吸附剂对Hg2+进行吸附，并利用磁分离特性与脱硫石膏分离，抑制Hg再释放，防止Hg在脱硫石膏中富集。通过实验研究结合理论分析，确立脱硫浆液中Hg2+还原机制，建立Hg2+还原模型；考察磁性石墨烯基吸附剂对脱硫石膏浆液中Hg2+吸附性能，阐述其对Hg2+吸附机理，建立其对Hg2+吸附动力学模型；进而利用Ag-Hg反应机理，在磁性石墨烯基吸附剂表面修饰纳米Ag颗粒，开发磁性石墨烯基复合吸附剂实现脱硫石膏浆液中Hg2+/Hg0联合吸附，并确立复合吸附剂分离再生化学工艺流程，评估其放量生产及工业应用前景，为WFGD系统同步脱Hg安全运行提供技术支撑，为拓展石墨烯基功能材料在能源环保领域利用奠定理论基础。

项目针对燃煤电站WFGD脱硫石膏浆液中Hg2+还原再释放，及Hg在脱硫石膏中富集问题开展相关研究工作，揭示了脱硫石膏浆液中Hg2+还原机理，开发了石墨烯基磁性复合吸附材料，考察了吸附剂对Hg0 和Hg2+的吸附性能级循环再生特性，对比分析了飞灰沸石对汞的吸附性能。系统研究了典型超低排放燃煤电站脱硫系统中重金属分布特性，揭示了重金属在脱硫系统中富集规律，重点阐述了Hg在脱硫系统中分布特性，及脱硫石膏中汞的热稳定性与形态。搭建了脱硫石膏浆液 Hg2+还原反应实验台架，并模拟燃煤电站脱硫浆液条件开展了脱硫浆液中Hg2+还原的实验研究，考察了PH值，温度，SO32-离子浓度，O2浓度等参数对Hg2+还原的影响，阐明了燃煤电站脱硫浆液中汞还原机理，为脱硫浆液中Hg的控制奠定了理论基础。开发了基于石墨烯的四种复合吸附剂，包括氧化石墨烯（GO）、纳米Fe3O4负载石墨烯复合材料(MGO)、纳米Ag颗粒修饰磁性氧化石墨烯（GO-Ag/MGO-Ag），并进行了系统表征，考察了氧化石墨烯及其复合物对Hg0及Hg2+的吸附作用，分析了吸附剂对汞吸附机理，考察了吸附剂的循环再生性。以燃煤电站飞灰为原料，通过水热合成沸石，并利用Ag-NPs进行修饰，考察了沸石基吸附剂对Hg0和Hg2+的吸附性能，对比分析了其与石墨烯基复合物对汞吸附的差异。项目执行期间共发表基金标注论文15篇，其中SCI收录12篇，EI收录15篇，参加国际会议4人次，国内学术会议4人次，协助培养研究生4名，指导本科生3名。