Skip to main content
Log in

Synthesis of SiO2–Al2O3 composite aerogel from fly ash: a low-cost and facile approach

  • Original Paper: Nano- and macroporous materials (aerogels, xerogels, cryogels, etc.)
  • Published:
Journal of Sol-Gel Science and Technology Aims and scope Submit manuscript


A low-cost and simple method was proposed to synthesize SiO2–Al2O3 composite aerogel from fly ash by alkali fusion-acid leaching-ambient pressure drying process just in 3 days for the first time. The effect of the leaching solution’s pH value upon micro-structure and properties of the as-prepared SiO2–Al2O3 composite aerogel was intensively studied by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, N2 adsorption-desorption, and Fourier transform infrared spectrometry. The as-formed SiO2–Al2O3 aerogel possessed high specific surface area (abbreviated as SSA) of 800 m2/g when the pH value was controlled at 2.7–3.1 (almost up to 900 m2/g at pH = 2.7). Meanwhile, the aerogel exhibited good thermal stability. After calcination at 900 °C for 2 h, the aerogel still remained an amorphous structure with a SSA of 77.88 m2/g. In addition, the related formation mechanism was also discussed.


  • SiO2–Al2O3 aerogels were firstly synthesized from fly ash by a simple method.

  • The composite aerogels possessed higher specific surface area of 897.30 m2/g.

  • The SiO2–Al2O3 aerogels exhibited good thermal stability.

  • The whole low-cost and facile treating process took only 3 days.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9
Fig. 10

Similar content being viewed by others


  1. Bheekhun N, Talib A, Rahim A, Hassan MR (2013) Aerogels in aerospace: an overview, Adv Mater Sci Eng 2013:1–18

    Article  Google Scholar 

  2. Dutoit D, Reiche M, Baiker A (1997) Vanadia-silica aerogels. Structure and catalytic properties in selective reductionof NO by NH3. Appl Catal B: Environ 13:275–288

    Article  CAS  Google Scholar 

  3. White S, Demko J, Tomich A, (2010) Flexible aerogel as a superior thermal insulation for high temperature superconductor cable applications. In: AIP Conference Proceedings. AIP, pp. 788–795

  4. Shi F, Wang L, Liu J (2006) Synthesis and characterization of silica aerogels by a novel fast ambient pressure drying process. Mater Lett 60:3718–3722

    Article  CAS  Google Scholar 

  5. Horiuchi T, Osaki T, Sugiyama T, Suzuki K, Mori T (2001) Maintenance of large surface area of alumina heated at elevated temperatures above 1300 °C by preparing silica-containing pseudoboehmite aerogel. J Non-Crystalline Solids 291:187–198

    Article  CAS  Google Scholar 

  6. Wen F, Yang XP (2012) Study on thermal protection materials applied to electronic memory embed in aircraft. Adv Mater Res 459:30–34

    Article  Google Scholar 

  7. Zhang R, Ye C, Wang B (2018) Novel Al2O3-SiO2 aerogel/porous zirconia composite with ultra-low thermal conductivity. J Porous Mater 25:171–178

    Article  CAS  Google Scholar 

  8. Wang HL, Qi HP, Wei XN, Liu XY, Jiang WF (2016) Photocatalytic activity of TiO2 supported SiO2-Al2O3 aerogels prepared from industrial fly ash. Chin J Catal 37:2025–2033

    Article  CAS  Google Scholar 

  9. Miller JB, Ko EI (1998) A homogeneously dispersed silica dopant for control of the textural and structural evolution of an alumina aerogel. Catal Today 43:51–67

    Article  CAS  Google Scholar 

  10. Gash AE, Tillotson TM, Satcher Jr JH, Hrubesh LW, Simpson RL (2001) New sol-gel synthetic route to transition and main-group metal oxide aerogels using inorganic salt precursors. J Non-Crystalline Solids 285:22–28

    Article  CAS  Google Scholar 

  11. Ji X, Zhou Q, Qiu G, Yue C, Guo M, Chen F, Zhang M (2018) Preparation of monolithic silica-based aerogels with high thermal stability by ambient pressure drying. Ceram Int 44:11923–11931

    Article  CAS  Google Scholar 

  12. Shi F, Liu JX, Song K, Wang ZY (2010) Cost-effective synthesis of silica aerogels from fly ash via ambient pressure drying. J Non-Crystalline Solids 356:2241–2246

    Article  CAS  Google Scholar 

  13. Hu W, Li M, Chen W, Zhang N, Li B, Wang M, Zhao Z (2016) Preparation of hydrophobic silica aerogel with kaolin dried at ambient pressure. Colloids Surf A: Physicochemical Eng Asp 501:83–91

    Article  CAS  Google Scholar 

  14. Bao W, Guo F, Zou H, Gan S, Xu X, Zheng K (2013) Synthesis of hydrophobic alumina aerogel with surface modification from oil shale ash. Powder Technol 249:220–224

    Article  CAS  Google Scholar 

  15. Tang Q, Wang T (2005) Preparation of silica aerogel from rice hull ash by supercritical carbon dioxide drying. J Supercrit Fluids 35:91–94

    Article  CAS  Google Scholar 

  16. Zhu J, Guo S, Li X (2015) Facile preparation of a SiO2-Al2O3 aerogel using coal gangue as a raw material via an ambient pressure drying method and its application in organic solvent adsorption. RSC Adv 5:103656–103661

    Article  CAS  Google Scholar 

  17. Gong X, Yao H, Zhang D, Qiao Y, Li L, Xu M (2010) Leaching characteristics of heavy metals in fly ash from a Chinese coal-fired power plant. Asia-Pac J Chem Eng 5:330–336

    Article  CAS  Google Scholar 

  18. Leventis N, Sotiriou-Leventis C, Zhang G, Rawashdeh AMM (2002) Nanoengineering strong silica aerogels. Nano Lett 2:957–960

    Article  CAS  Google Scholar 

  19. Poco J, Satcher Jr J, Hrubesh L (2001) Synthesis of high porosity, monolithic alumina aerogels. J non-crystalline solids 285:57–63

    Article  CAS  Google Scholar 

  20. Wu L, Huang Y, Wang Z, Liu L, Xu H (2010) Fabrication of hydrophobic alumina aerogel monoliths by surface modification and ambient pressure drying. Appl Surf Sci 256:5973–5977

    Article  CAS  Google Scholar 

  21. Gan L, Xu Z, Feng Y, Chen L (2005) Synthesis of alumina aerogels by ambient drying method and control of their structures. J Porous Mater 12:317–321

    Article  CAS  Google Scholar 

  22. Ling X, Li B, Li M, Hu W, Chen W (2018) Thermal stability of Al-modified silica aerogels through epoxide-assisted sol-gel route followed by ambient pressure drying. J Sol-Gel Sci Technol 87:83–94

    Article  CAS  Google Scholar 

  23. Eris G, Sanli D, Ulker Z, Bozbag SE, Jonás A, Kiraz A, Erkey C (2013) Three-dimensional optofluidic waveguides in hydrophobic silica aerogels via supercritical fluid processing. J Supercrit Fluids 73:28–33

    Article  CAS  Google Scholar 

  24. Abenojar J, Colera I, Martínez MA, Velasco F (2010) Study by XPS of an atmospheric plasma-torch treated glass: influence on adhesion. J Adhes Sci Technol 24:1841–1854

    Article  CAS  Google Scholar 

  25. Liao J, Gao P, Xu L, Feng J (2018) Influence of heating loading conditions on the composition and microstructure of SiO2 aerogel. Mater Sci Technol 26:33–39

  26. Brajpuriya R, Shripathi T (2009) Investigation of Fe/Al interface as a function of annealing temperature using XPS. Appl Surf Sci 255:6149–6154

    Article  CAS  Google Scholar 

  27. Tan P (2016) Active phase, catalytic activity, and induction period of Fe/zeolite material in nonoxidative aromatization of methane. J Catal 338:21–29

    Article  CAS  Google Scholar 

  28. Stumm W, Huper H, Champlin RL (1967) Formulation of polysilicates as determined by coagulation effects. Environ Sci Technol 1:221–227

    Article  CAS  Google Scholar 

  29. Letterman RD, Amirtharajah A, O’Melia CR (1999) Coagulation and flocculation. In: Water quality and treatment, 5th edn. American Water Works Association, Denver

  30. Flynn Jr CM (1984) Hydrolysis of inorganic iron (III) salts. Chem Rev 84:31–41

    Article  CAS  Google Scholar 

  31. Kruk M, Jaroniec M, Sayari A (1997) Application of large Pore MCM-41 molecular sieves to improve pore size analysis using nitrogen adsorption measurements. Langmuir 13:6267–6273

    Article  CAS  Google Scholar 

  32. Armor J, Carlson E (1987) Variables in the synthesis of unusually high pore volume aluminas. J Mater Sci 22:2549–2556

    Article  CAS  Google Scholar 

  33. Li W, Zhao D (2013) An overview of the synthesis of ordered mesoporous materials. Chem Commun (Camb) 49:943–946

    Article  CAS  Google Scholar 

Download references


This work was financially supported by the National Natural Science Foundation of China (No. U1810205), the National Basic Research Program of China (No. 2014CB643401).

Author information

Authors and Affiliations


Corresponding author

Correspondence to Min Guo.

Ethics declarations

Conflict of interest

The authors declare that they have no conflict of interest.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Shen, M., Jiang, X., Zhang, M. et al. Synthesis of SiO2–Al2O3 composite aerogel from fly ash: a low-cost and facile approach. J Sol-Gel Sci Technol 93, 281–290 (2020).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: