Abstract
Advanced SiO2–Al2O3 aerogel materials have outstanding potential in the field of thermal insulation. Nevertheless, the creation of a mechanically robust and low-cost SiO2–Al2O3 aerogel material remains a considerable challenge. In this study, SiO2–Al2O3 aerogel based on coal gangue, which is a type of zero-cost inorganic waste, was constructed in porous agarose aerogel beads, followed by simple chemical vapor deposition of trimethylchlorosilane to fabricate SiO2–Al2O3/agarose composite aerogel beads (SCABs). The resulting SCABs exhibited a unique nanoscale interpenetrating network structure, which is lightweight and has high specific surface area (538.3 m2/g), hydrophobicity (approximately 128°), and excellent thermal stability and thermal insulation performance. Moreover, the compressive strength of the SCABs was dramatically increased by approximately a factor of ten compared to that of native SiO2–Al2O3 aerogel beads. The prepared SCABs not only pave the way for the design of a novel aerogel material for use in thermal insulation without requiring expensive raw materials, but also provide an effective way to comprehensively use coal gangue.
Highlights
The properties of the obtained SiO2–Al2O3/agarose composite aerogel beads (SCABs) could be adjusted by changing the volume of water added to the Activatedcoal coalgangue gangue (ACG) and the concentration of the agarose solution
Based on the above analysis of the microstructure and energy dispersive spectrum (EDS) of SCABs, it could be proved that the obtained samples exhibited a unique nanoscale interpenetrating network struc‐
Based on the above analysis of the microstructure and EDS of SCABs, it could be proved that the obtained samples exhibited a unique nanoscale interpenetrating network structure which was formed by the construction of rigid SiO2 –Al2 O3 gel skeleton in the void space of the flexible agarose gel skeleton network
Summary
All these methods improve the strength of the gel skeleton in the gelation process to mitigate the drawbacks of high brittleness of inorganic oxide aerogels This enhancement of mechanical properties of inorganic oxide aerogels using these methods comes at the cost of sacrificing other functionality, for example, by increasing thermal conductivity and density or decreasing porosity and specific surface area [28–30]. To the best of our knowledge, the aerogel beads prepared in this study are among the first to demonstrate effective performance in all these aspects without any major sacrifices These SCABs have both a low cost and outstanding mechanical properties, and are expected to be applied for use in thermal insulation.
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