氧化锆溶胶-凝胶形成与界面传递相耦合的介尺度机理研究

For the multiple -scale materials preparation from molecule in nanometers to particle in micrometers, meso-scale mechanism provides meaningful guidance to explaining the microscopic behavior of reactions coupled with interface transport and regulating the structure and performance of the materials. However, it is difficult to explain the microscopic behavior of the sel/gel formation coupled with the inerface transport due to the unavailable meso-scale mechanism. Based on our previous study (successful production of sol particles with diameter less than 10 nm), this work is devoted to exploring the meso-scale mechanism for the formation of sol and gel, as well as quantifying the effect of the chemical formation of sol and physical evolution of gel on the structure and performance of meso-scale materails. To achieve this, this work, taking Zirconia nanofiltration membrane as the reasearch object, will investigate the effect of several key parameters, including the reaction route for zirconium salt hydrolyzation, the environmental conditions for drying process and the methods for thermal processing, on the multiple-scale (solution-precipitate-sel-gel) reaction and its formation rate as well as the evolution process of gelation on microcosmic surface. The research achievement is beneficial to finding out the effect of reaction route and operational conditions on the structure and performance of ceramic nanofiltration membrane. This work will underpin much of the design and regulation of ceramic nanofiltration membrane, as well as making significant contribution to the large-scale preparation of meso-microporous membrane in process industry.

在涉及从分/离子到颗粒的多尺度材料制备过程中，介尺度机制对阐述微观反应和传递行为、调控材料的结构和性能具有重要指导意义。但目前溶胶/凝胶过程涉及的介尺度行为机理尚不明确，使溶胶/凝胶形成、转化和界面传递耦合的微观现象无法解释。本项目在实验研究成功合成径粒小于10nm的颗粒溶胶基础上，进一步探索颗粒溶胶形成与界面凝胶化反应的介尺度机理，量化溶胶反应及凝胶演化对介尺度结构及性能的影响。以氧化锆纳滤膜为研究对象，研究锆盐水解反应路线、干燥环境调控及高温热处理等工艺参数对“溶液-水合物沉淀-溶胶-凝胶”多尺度反应和转化速率及界面凝胶化结构演变微观过程的影响，揭示溶胶/凝胶转化过程中的反应路径、实验条件与陶瓷纳滤膜材料的结构与性能的影响规律，完善颗粒溶胶-凝胶反应与传递的介尺度理论。该项目的实施为陶瓷纳滤膜结构和性能的定向设计、调控奠定了理论基础，为解决过程工业中大规模制备完整介孔/微孔膜作出贡献。

陶瓷纳滤膜材料具有机械强度高、化学稳定性好、耐高温、耐酸碱及有机溶剂等优异性能，是过程工业苛刻环境下精密分离的理想膜材料，研究介尺度下溶胶凝胶过程参数对膜材料的结构与性能的关系，对于设计和指导高性能陶瓷纳滤膜的可控化制备具有重要意义。本课题设计了合理可行的锆盐金属离子水解反应生成水合物沉淀及介尺度稳定颗粒溶胶的实验路线，结合制膜液中分子/离子间的热力学机理和胶体颗粒间的电荷作用，通过调控前驱体浓度、反应温度及时间、掺杂元素、陈化时间等实验参数条件，在超声强化以及有机添加剂引入的改进路线下，合成了纳米颗粒溶胶并实现了对粒径的精确调控。针对介孔载体和颗粒溶胶的物理化学性质，分析毛细作用和蒸发对凝胶膜制备的影响，调控温度、湿度及时间等实验参数条件，采用浸浆-干燥法制备孔结构可控的凝胶层，通过调试和优化热处理工艺条件，掺杂纳米钇、钯、银等元素抑制材料晶型转变、提高陶瓷膜韧性，制备完整无缺陷的高性能陶瓷纳滤膜。同时基于椭偏表征技术，建立了陶瓷膜-椭偏微结构的表征方法，定量表征从凝胶膜到陶瓷膜微结构演变过程。研究了热处理过程对介孔/微孔膜结构的影响，通过元素掺杂、物相调整以及煅烧工艺优化等对高温固相反应中相转变和晶粒增长进行有效控制，建立了氧化锆膜的热处理工艺(煅烧温度、升温速率、气氛等)与膜材料结构和性能间的相互关系，同时利用水热法实现了纳米氧化锆的高产化，为定量制备氧化锆陶瓷纳滤膜奠定了基础。