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硅酸盐通报 ›› 2022, Vol. 41 ›› Issue (10): 3667-3674.

• 陶瓷 • 上一篇    下一篇

硅酸钠模数对SiO2气凝胶结构和表面改性机制的影响

徐静, 赵永奇, 徐成强, 窦金孝, 赵小蕙, 余江龙   

  1. 辽宁科技大学化学工程学院,辽宁先进煤焦化省重点实验室,鞍山 114051
  • 收稿日期:2022-04-22 修回日期:2022-07-11 出版日期:2022-10-15 发布日期:2022-10-26
  • 通讯作者: 余江龙,博士,教授。E-mail:jianglongyu@163.com
  • 作者简介:徐静(1979—),女,博士,讲师。主要从事煤炭清洁利用和生物质热解研究。E-mail:xujingas@163.com
  • 基金资助:
    辽宁省高水平创新团队培养项目(2018LNGXGJWPY-YB010);辽宁省教育厅优秀人才培育项目(2020LNQN21)

Effect of Sodium Silicate Modulus on Structure and Surface Modification Mechanism of SiO2 Aerogel

XU Jing, ZHAO Yongqi, XU Chengqiang, DOU Jinxiao, ZHAO Xiaohui, YU Jianglong   

  1. Key Laboratory for Advanced Coal and Coking Technology of Liaoning Province, School of Chemical Engineering, University of Science and Technology Liaoning, Anshan 114051, China
  • Received:2022-04-22 Revised:2022-07-11 Online:2022-10-15 Published:2022-10-26

摘要: 以粉煤灰为原料制备五种不同浓度的硅酸钠溶液,采用溶胶-凝胶法对硅酸钠溶液进行处理,在常压干燥条件下获得了疏水性SiO2气凝胶。通过测试气凝胶的密度、比表面积和接触角,研究了硅酸钠溶液模数m对气凝胶结构的影响,阐述了气凝胶表面疏水改性的亲核取代SN1化学反应机制。研究结果表明,气凝胶的疏水性能与其表面连接的硅甲基—Si—(CH3)3数目有直接关系,当硅酸钠模数m=2.50时,气凝胶的疏水性能最佳。气凝胶的密度和比表面积均随硅酸钠模数的增大而增大,当硅酸钠模数m=0.75时,气凝胶的密度和比表面积最小,其值分别为0.073 9 g/cm3和588.5 m2/g。

关键词: 气凝胶, 硅酸钠, 溶胶-凝胶, 粉煤灰, 模数, 疏水性

Abstract: Five different concentrations of sodium silicate solutions were prepared from fly ash. The sodium silicate solutions were treated by sol-gel method, and hydrophobic SiO2 aerogel was obtained via ambient pressure drying. The influence of sodium silicate modulus on the structure of aerogels was investigated through measurements of density, specific surface area and contact angle. The chemical reaction mechanism of nucleophilic substitution SN1 for hydrophobic modification of aerogel surface was proposed. The results show that the hydrophobic performance of aerogel is directly related to the number of —Si—(CH3)3 attached to the surface. When sodium silicate modulus is equal to 2.50, the best hydrophobic performance of aerogel is achieved. The density and specific surface area of aerogel increase with the increase of sodium silicate modulus. When the sodium silicate modulus is equal to 0.75, the lowest density and specific surface area of aerogel are recorded, which are 0.073 9 g/cm3 and 588.5 m2/g, respectively.

Key words: aerogel, sodium silicate, sol-gel, fly ash, modulus, hydrophobicity

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