Preparation of SiO2 aerogel by water glass: effect of different sodium removal methods on aerogel properties

IF 2.3 4区材料科学 Q2 MATERIALS SCIENCE, CERAMICS

Journal of Sol-Gel Science and Technology Pub Date : 2024-11-02 DOI:10.1007/s10971-024-06413-w

Wei Sun, Lu Yu, Jikai Su, Ruixiang Liu, Xuemei Yan, Dong Su, Pengyu Zhang, Xiaolei Li

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Abstract

Removal of Na⁺ is a very important step in the SiO₂ aerogel preparation using water glass as precursor, which has a significant effect on the structure and properties of aerogel. In this study, three methods (Solution-crystallization, Water washing, and Ion exchange) were used to remove Na⁺ from the system and investigated the effects of different methods on the aerogel properties. The results show that all three aerogels have low bulk density (<0.075 g/cm³), low thermal conductivity (≤0.015 W/(m·K)), and well hydrophobicity (θ ≥ 137°). Among them, Na⁺ exists in the sol in the sodium removal process by water washing and effects the uniformity of gel network. The samples for sodium removal by solution-crystallization show better hydrophobicity and poorer high-temperature stability, which is related to the presence of abundant hydrophobic groups (Si-OC₂H₅) on the gel surface. The microstructure and the pore size distribution of the aerogels prepared by ion exchange are uniform, which makes them have optimal comprehensive performance. The mechanism of solution-crystallization effect in the process of sodium removal was explored, providing a workable idea for low-cost preparation of SiO₂ aerogel.

Graphical Abstract

Abstract Image

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水玻璃法制备SiO2气凝胶：不同除钠方法对气凝胶性能的影响

在以水玻璃为前驱体制备SiO2气凝胶的过程中，Na+的去除是一个非常重要的步骤，它对气凝胶的结构和性能有着重要的影响。本研究采用溶液结晶、水洗和离子交换三种方法去除体系中的Na+，并研究了不同方法对气凝胶性能的影响。结果表明，三种气凝胶均具有低堆积密度（<0.075 g/cm3）、低导热系数（≤0.015 W/(m·K)）和良好的疏水性（θ≥137°）。其中，Na+在水洗除钠过程中存在于溶胶中，影响凝胶网络的均匀性。溶液结晶法脱钠样品的疏水性较好，高温稳定性较差，这与凝胶表面存在丰富的疏水基（Si-OC2H5）有关。离子交换法制备的气凝胶的微观结构和孔径分布均匀，具有最佳的综合性能。探讨了除钠过程中溶液结晶效应的机理，为低成本制备SiO2气凝胶提供了可行思路。图形抽象

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Journal of Sol-Gel Science and Technology 工程技术-材料科学：硅酸盐

CiteScore

4.70

自引率

4.00%

发文量

280

审稿时长

2.1 months

期刊介绍： The primary objective of the Journal of Sol-Gel Science and Technology (JSST), the official journal of the International Sol-Gel Society, is to provide an international forum for the dissemination of scientific, technological, and general knowledge about materials processed by chemical nanotechnologies known as the "sol-gel" process. The materials of interest include gels, gel-derived glasses, ceramics in form of nano- and micro-powders, bulk, fibres, thin films and coatings as well as more recent materials such as hybrid organic-inorganic materials and composites. Such materials exhibit a wide range of optical, electronic, magnetic, chemical, environmental, and biomedical properties and functionalities. Methods for producing sol-gel-derived materials and the industrial uses of these materials are also of great interest.