Robust SiO2–Al2O3/Agarose Composite Aerogel Beads with Outstanding Thermal Insulation Based on Coal Gangue

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.

Fabrication and application of porous materials made from coal gangue: A review

“…It is shown that the specific surface area of the SiO 2 -Al 2 O 3 aerogel prepared from CG is comparable to that of aerogel prepared from relatively expensive raw materials such as Al(NO 3 ) 3 ⋅9H 2 O or aluminum isopropanol and tetraethoxysilane under supercritical drying conditions. As shown in Figure 13, Gu et al 132…”

“…In addition to the aforementioned classic micro-and mesoporous materials, other high value-added porous products, such as aerogels, 50,51,132,133 porous carbon materials, 55,134,135 gangue-biochar composite materials, 136 and C/SiO x composite materials, 137 can also be prepared by using CG as the raw material.…”

“…Due to the high content of SiO 2 in CG (approximately 40-70 wt%), silica is often extracted from CG, and aerogel is then prepared by other processes. At present, silica aerogel 50,133 and silica-alumina aerogel 51,132 are most often prepared. Zhu et al 50 pre-pared granular silica aerogel materials by extracting silica from recycled silicon-rich CG through one-step hydrophobic and atmospheric drying.…”

Natural Materials for 3D Printing and Their Applications

“…Agarose (AG) is a polysaccharide derived from red algae, whose basic structure is 1,4-linked 3,6-anhydro-α-L-galactose and a 1,3-linked β-D-galactose alternating long-chain [ 44 ]. Due to its biocompatibility, non-toxicity, and adjustable characteristics, AG can be well applied in vascular regeneration and skin repair [ 45 ].…”

Elastic Agarose Nanowire Aerogels for Oil–Water Separation and Thermal Insulation

“…Recently, aerogels have attracted significance attention in the fields of oil–water separation and thermal insulation because of their extremely low density (0.003–0.5 g/cm 3 ), high porosity (80–99.8%), and large specific surface area (500–1200 m 2 /g). − Nevertheless, traditional inorganic aerogels with pearl-necklace-like network structures, such as SiO 2 or Al 2 O 3 aerogels, , cannot be used for these purposes because of their high brittleness and weak mechanical strength. , To date, many carbon-based aerogels with excellent mechanical properties have been developed, such as carbon nanotubes and graphene aerogels. , Unfortunately, the practical application of these aerogels is challenging due to disadvantages such as their high manufacturing cost (e.g., resulting from the expensive equipment and complex technologies) …”