聚乙二醇强化钛液水解晶种活性及偏钛酸产品质量调控研究

Due to the inactivated seed for hydrolysis process in titanyl sulfate solution, the acromatic ability of the rutile product obtained from hydrated titanium dioxide with broad PSD (particle size distribution) and irregular morphology, is much lower than the one from chloride process. Focus on the key scientific problems of controlling the synthesis of seed and titanium hydrolysis process, a novel method by adding polyethylene glycol (PEG) was invented to improve the quality of hydrated titanium dioxide. Using the composite method of structural chemistry, interfacial chemistry, reaction kinetics, and mass transfer to reveal the interfacial controlling law as follows: (1) PEG inhibits the agglomerated inactivition of seed by modifying the interfacial structure in synthesis process. (2) PEG inhibits the dissolved inactivition of seed by modifying the interfacial structure in synthesis process. (3) In the hydrolysis process, the ether and hydroxyl-type group of PEG promote Ti-O of metatitanic growth in specific direction to get narrow PSD. (4) The chemical field with PEG and seed effectively achieve the cooperative control the hydrolytic product quality (size, morphology and purity). Implementation of this project will improve the TiO2 quality, and provide novel idea and necessary theoretical basis to upgrade the product engineering of titanium hydrolysis in titanyl sulfate solution.

针对硫酸氧钛溶液水解过程晶种失活导致偏钛酸粒径分布宽，形貌不规则，金红石型钛白粉遮盖力和分散性差于氯化法的问题，本项目提出了采用聚乙二醇（PEG）稳定晶种活性，并与晶种协同调控水解过程提高偏钛酸质量的新方法。采用结构化学-界面化学-反应动力学相交叉的科学方法，深入研究PEG抑制水解晶种合成过程中团聚失活、抑制晶种加入钛液过程中溶解失活、晶种与PEG界面协同调控水解产物偏钛酸的成核生长速率和粒径分布的关键问题。解析PEG近程、远程、聚集态结构和晶种微观结构，阐明PEG稳定晶种活性机制，揭示晶种协同PEG促进偏钛酸Ti-O定向生长机理，建立偏钛酸粒径、形貌调控机制，以期获得粒径适中、粒度均一的偏钛酸，经煅烧制备结构缺陷少、形貌规整、光学性能与氯化法相当的金红石型钛白粉。本项目的实施将为硫酸氧钛溶液液相水解制备偏钛酸技术，提高钛白粉质量提供新思路和必要理论基础。

本项目是以硫酸氧钛溶液为研究对象，开展外添加剂聚乙二醇（简称PEG）调控晶种合成−水解过程的研究，实现水解过程精确调控，获得粒径均一、形貌规整、光学性能优异的水解产品。在基金支持下，本项目按照计划对以下三方面进行了研究：① 晶种合成过程中PEG抑制晶种团聚失活机制；② 晶种加入钛液过程中PEG抑制晶种溶解失活机制；③ 水解过程中PEG对偏钛酸成核−生长速率和粒径形态的界面调控机理。.研究结果表明，（1）除了PEG官能团（C-O-C、-OH）的稳定作用，PEG锯齿直链状远程结构和聚集态，通过成键和空间效应实现对晶种活性的界面调控，使晶种制备区域从10~13 min增宽至10~20 min，具有一定的工业应用前景。（2）添加质量比为2%的PEG1000制备的晶种在高酸度钛液中活性最高。（3）PEG比钛液其他带电荷基团（HSO4-、SO42-、SiO44-）竞争力强。（4）晶种添加量为2%时，水解偏钛酸粒度有最优值（1.39μm）。（5）PEG和晶种对钛液水解过程偏钛酸生长的精确调控具有协同作用。.本项目通过添加剂聚乙二醇（简称PEG）界面调控硫酸氧钛溶液水解晶种和偏钛酸的Ti-O生长形态和粒径分布，实现PEG稳定晶种活性、晶种和PEG协同调控水解过程的目标，获得了粒径均一、形貌规整、光学性能优异的水解产品。本项目的实施，将为现有钛白粉行业合成高颜料性能的钛白粉产品提供理论依据和应用基础，有望降低现有工业成本，具有重要的学术意义和应用背景。