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. 2022 Oct 26;8(11):691.
doi: 10.3390/gels8110691.

Organic Bio-Based Aerogel from Food Waste: Preparation and Hydrophobization

Giulia Gaggero  1 , Raman P Subrahmanyam  2 , Baldur Schroeter  2 , Pavel Gurikov  3 , Marina Delucchi  1
Affiliations

Organic Bio-Based Aerogel from Food Waste: Preparation and Hydrophobization

Giulia Gaggero et al. Gels. .

Abstract

In this work, organic aerogels from spent ground coffee and apple pomace were prepared and characterized for the first time. Apple aerogel was found to be much lighter than that from coffee (0.19 vs. 0.016 g/cm3, whereas the specific surface areas are comparable (229 vs. 208 m2/g). Being intrinsically hydrophilic, these aerogels were silanized, both in liquid and gas phase, to increase stability in aqueous media. The latter modification method allowed chemical grafting of the silane to the aerogel surface (evidenced by FTIR and TGA) and resulted in certain hydrophobicity, as was evidenced via contact angle measurements: both aerogels possess a contact angle of ca. 100° after the gas hydrophobization, while for the pristine aerogels it was 50°. Furthermore, it was observed that the gas-phase silanization process is more applicable to apple aerogels.

Keywords: aerogel; bio-based; hydrophobization; organic.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
SEM micrographs of coffee aerogels at (a) 100× magnification and (b) 500× magnification. SEM micrographs of apple aerogels at (c) 100× magnification and (d) 500× magnification.
Figure 2
Figure 2
SEM micrographs at 100× magnification of: (e) coffee aerogels after water immersion test, (f) apple aerogels after water immersion test.
Figure 3
Figure 3
FTIR spectra collected in ATR mode of pristine aerogel (black curves), after LPM silanization (red curves), and after GPM silanization (blue curves). (a) CA, HCA(l) and HCA(g). (b) AA, HAA(l) and HAA(g).
Figure 3
Figure 3
FTIR spectra collected in ATR mode of pristine aerogel (black curves), after LPM silanization (red curves), and after GPM silanization (blue curves). (a) CA, HCA(l) and HCA(g). (b) AA, HAA(l) and HAA(g).
Figure 4
Figure 4
Thermal stability investigation. TGA and DTG profiles of pristine aerogel (black curves), LPM silanization (red curves), and GPM silanization (blue curves). (a) CA, pristine and after LPM and GPM treatment, (b) AA, pristine and after LPM and GPM treatment.
See this image and copyright information in PMC

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