褐煤基多级孔吸附材料结构演化规律及对染料分子吸附机制研究

There are large lignite reserves in China, and the abundant oxygen functional groups, porous structures and low price of lignites provide a good application prospect for the preparation of the multi-stage porous adsorption material. The dehydration and regulation of the surface properties and porous structures of lignite are the prerequisite to be an effective adsorption material. This project focuses on the evolution of lignite structures in the thermal process and the lignite-dye molecule-water molecule interaction and structure matching mechanism. The research route is from lignite modification to adsorption behavior, then adsorption mechanism and then structure matching regulation. The real-time temperature process of dry/wet zone in lignite particles during the multi-stage heating process will be analyzed, and its effect on the evolution mechanism of multi-stage porous structure and the active sites. Secondly, we will study on the interaction between lignite-dye-water molecules to establish matching mechanism between lignite adsorption sites distribution/spatial structure and dye molecules, and reveal the synergistic promotion, competitive adsorption and steric hindrance in the process of multi-molecules adsorption through static adsorption experiment and molecular simulation. And then the lignite adsorption sites distribution/spatial structure, dye molecular structure and waste water solution characteristics will be parameterized to construct multi-parameter lignite adsorption prediction model for dye molecular. Finally, control mechanism of lignite adsorption sites distribution and spatial structure will be established, and this will have great significance for the characteristic control of lignite-based porous material and the preparation of cheap adsorbent.

我国褐煤资源保有储量大，丰富的活性基团、发达的孔道结构和低廉的价格为其制备多级孔吸附材料提供了良好的基础条件，原煤中高赋存水的释放以及表面特性和空间结构的调控是褐煤成为高效吸附材料的必要环节。本项目围绕褐煤受热结构演化规律和褐煤-染料分子-水分子相互作用及结构匹配机制等科学问题，以褐煤改性-吸附行为-吸附机理-结构匹配调控为研究思路开展科学研究。从多段受热过程中褐煤颗粒干区/湿区的实时温度对多级孔结构和活性位点分布演化机制的影响出发，通过褐煤-染料分子-水分子间相互作用和吸附行为研究，建立褐煤与染料分子吸附位点分布和空间结构匹配机制，揭示多分子吸附过程中协同促进、竞争吸附和空间位阻效应，将褐煤空间结构和活性基团分布、染料分子结构以及废水溶液特性进行多参数化处理，构建吸附预测模型，最终建立褐煤吸附位点分布和空间结构调控机制，对褐煤基多孔吸附材料特性调控和廉价吸附剂制备具有一定指导意义。

本研究以褐煤改性-吸附行为-结构匹配调控为研究思路，明确了快速升温-降温、活化等过程对褐煤多级孔结构演化的影响，实现了褐煤基吸附材料多级孔结构的可调可控；将褐煤组成和结构参数进行参数化处理，通过机器学习方法实现对活性焦吸附效果预测和各因素重要程度的分析，发现活性焦在吸附小分子污染物时，比表面积和孔容对吸附量有主导作用，在吸附大分子污染物时，孔容和平均孔径影响较大；提出了引入微纳气泡促进褐煤基吸附剂吸附动力学过程的方法，有效提高吸附速率。本研究对褐煤基多孔吸附材料特性调控和廉价吸附剂制备具有一定指导意义。