基于差异性摩擦带电与介电泳的麦麸糊粉层静电分离技术的基础研究

In view of the fact that the low utilization rate of wheat aleurone, as well as the deficiency of the current theoretical research on the electrostatic separation of cereal bio-material, this study is designed to carry out a theoretical research on triboelectric separation (TES), focusing on the two key scientific matters in the TES of wheat aleurone, namely the material basis of wheat bran layers for their tribocharging difference, and the dielectrophoresis migration mechanism of charged wheat bran particles in non-uniform electric filed (NUFE). Firstly, the material structure on the surface of wheat bran layers, including microstructure, constitute and distribution of macromolecular and functional group, surface work function, et al., will be studied using the in-situ test methods. After that, the tribocharging properties of wheat bran layers, after being rubbed by the materials with different functional groups and surface work functions, will be analyzed using the film-friction-induction measure technology, to clarify the relationship between the tribocharging properties of wheat bran layers and their surface material structures. Then, the friction, collision, charging behaviors and mechanism of bran particles in different tribochargers, and the migration patterns of the charged particles in the NUFE will be studied based on the simulation technology. Lastly, the effective tribomaterial, tribocharger and electrostatic field for the TS of wheat aleurone will be built, and the mathematical interrelationship among the efficiency of TS, particle properties, electric field parameters and medium conditions will be obtained. Thus, the key problem in the TES of cereal biomass will be resolved, offering solid theoretical foundation to guide the application of TES in other biomass.

针对麦麸糊粉层利用率低的现状与谷物生物质静电分离理论研究的不足，课题围绕麦麸糊粉层摩擦电选的两个关键科学问题：麦麸结构层差异性摩擦带电的物质基础；非差异带电的麦麸微粒在非匀强静电场中的介电泳迁移规律，展开基础理论研究。课题欲采用原位探测手段，探明麦麸结构层在微观形貌、大分子与官能团组成及分布、表面功函等方面的表面物质结构特征差异，利用薄膜摩擦感应微电荷测定技术，分析不同表面功函和官能团的材料对麦麸结构层摩擦带电的影响机制，结合两者的结果，揭示麦麸结构层差异性摩擦带电与表面物质结构特性的内在关联；基于仿真模拟，掌握麦麸微粒在摩擦器中的摩擦、碰撞和带电规律，并解析带电麦麸微粒在非匀强静电场中的介电泳迁移规律。最终，构建利于糊粉层高效摩擦电选的摩擦材料、摩擦器和静电场，并建立摩擦电选效率-粉体特性-电场参数-介质条件的关联模型，从而完善谷物生物质摩擦电选的基础理论，为摩擦电选的广泛应用提供支撑。

静电场分离技术是一种新型的干法分离技术，主要基于欲分离物料的表面物质结构和电特性差异而实现。然而，静电分离在谷物生物质分离中的相关基础理论缺乏。本项目通过原位探测手段，研究了麦麸结构层的表面物质组成、显微结构和电学特性，并仿真模拟了带电麦麸微粒在静电场中的迁移行为，旨在建立麦麸结构层静电分离基础理论。研究发现，麦麸结构层的显微结构差异明显，具有可定量其比例的化学标示物，其表面的Ara与Xyl的含量之比，以及含苯环组分的含量（阿魏酰单体及聚体、酚脂）明显不同，是其差异性摩擦带电的主要物质结构基础；经超薄切片后，利用UPS和开尔文探针显微镜分别测定麦麸结构层的功函和表面电势，得出麦麸结构层的摩擦带电序列为：淀粉＞糊粉层＞中间层＞外果皮。麦麸糊粉层与外果皮的介电性和电阻性均具有明显差异，理论上可通过电晕带电和介电泳实现分离；对比不同带电方式得出，麦麸粉体经气-固管道摩擦带电所获电荷量较电晕带电高两个数量级，且不同麦麸结构层所获电量差异明显，是麦麸粉体获取电荷的优选方式；比较不同摩擦器的摩擦带电效果发现，管道式摩擦器较狭缝式具有明显优势，粉体的带电效果与长度、气流速度正相关，与狭缝间距或管道直径负相关；对比不同摩擦材料的摩擦带电效果得出，聚四氟乙烯和Nylon等在摩擦电序中远离纤维素的高聚物可作为麦麸生物质摩擦带电的优选材料。本研究还首次验证了介电泳富集麦麸结构层粉体的可行性，并得出了麦麸微粒在静电场中迁移行为与颗粒初速度、粒径、电场参数等的关系模型，建立了仿真模拟麦麸生物质静电分离行为的方法。本项目通过物质结构原位分析手段和仿真模拟技术，探明了麦麸生物质差异性摩擦带电的物质基础，验证了介电泳分离麦麸粉体的可行性，初步建立了麦麸生物质静电场分离在此两个方面的基础理论，为静电分离技术在谷物生物质中的应用提供了理论支撑。