Fabrication and Properties of Hybrid Coffee-Cellulose Aerogels from Spent Coffee Grounds

Abstract

A fully biodegradable hybrid coffee-cotton aerogel has been successfully developed from spent coffee grounds, 100% cotton fiber and polyvinyl alcohol (PVA) flakes via environmental friendly processes. The cotton fibers in coffee aerogel help to maintain the structure and improve the overall properties of the new hybrid coffee-cotton aerogel. The results show that increasing the concentration of fibers, while keeping the concentration of spent coffee grounds constant, the sinking of coffee ground particles in solution and shrinking effect on the aerogels are minimized and the overall mechanical and oil absorption properties are improved. The developed hybrid aerogels possess high porosity of 92–95% and super-hydrophobicity with an average water contact angle of 139°. Oil absorption capacity achieves 16 g/g with 0.50 wt.% of cotton fibers inside the coffee aerogel. Their thermal conductivity is in the range of 0.037–0.045 W/mK and compressive Young’s modulus achieves highest at 15.6 kPa. The properties of the hybrid aerogel indicate it as a potential material in several applications such as thermal insulation, oil absorption and filtration.

Liquid Transport and Real-Time Dye Purification via Lotus Petiole-Inspired Long-Range-Ordered Anisotropic Cellulose Nanofibril Aerogels

“…For a 0.0588 g CP-dc, it could withstand a 200 g weight in its longitudinal direction without collapsing (Figure 5b), which proved its excellent compression resistance. This lightweight but high-strength characteristic was also superior to previously reported aerogels, e.g., 1-CNF aerogel, 28 2-CNF aerogel, 29 3- cellulose nanocrystal aerogel, 30 4-CNF aerogel modified via CVD of methyltrimethoxysilane, 31 5-TEMPO-CNF aerogel, 32 6-cellulose nanocrystal aerogel, 33 7-CNF aerogel, 34 8-CNF aerogel, 35 9-cross-linked CNF aerogel, 36 10-CNF/graphene oxide/sepiolite nanorod aerogel, 37 11-CNFs/AgNW@Fe 3 O 4 sponge, 38 12-cellulose/poly(vinyl alcohol) (PVA) aerogel, 39 13-CNFs/AgNWs sponge, 17 14-cellulose/silica aerogel, 40 and 15-coffee/cellulose/PVA aerogel 41 (Figure 5c and Table S2).…”

PDMS – Coated pomelo peel carbon aerogel: Synthesis, characterization, and oil removal application

“…[ 7 ] After being coated with PDMS, PDMS/PCA sample exhibited two characteristic peaks at 1100 and 800 cm ‐1 , corresponding to vibrational stretching of Si–C and –CH 3 in siloxane compound, respectively. [ 21,22 ] Moreover, the intensity of characteristic peaks between 2950 and 2970 cm ‐1 increased significantly in the spectrum of PDMS/PCA. It can be explained by the addition of –CH 3 from –O–Si–(CH 3 ) 3 of PDMS, displacing –OH groups, therefore, enhancing the hydrophobicity of PDMS/PCA.…”

“…The fitting results of the experimental data (table 2) show that the calculated R 2 value from the pseudo‐second‐order model reaches 0.99 which higher than that of the other ones. [ 21 ] This result showed that the adsorption behavior of PDMS/PCA for both cooking and lubricating oils obeyed to pseudo‐second‐order model, considering the chemical sorption phenomenon. [ 10 ] Furthermore, the adsorption stability of the PDMS/PCA for two investigated oil was evaluated for 5 cycles of adsorption ‐ compression as presented in Fig.…”

“…The results show that coating PDMS/PCA had successfully achieved hydrophobicity by dip-coating in PDMS. [21,23] Furthermore, the water resistance stability of PDMS/PCA was observed in figure 5e. The result illustrates a slight decrease of WCA from 101.6 to 100.3 o after 14 days and 99.5 o after 21 days but still maintaining over 90 o , indicating the toughness and stability of the PDMS coating layer.…”

Insights into sustainable aerogels from lignocellulosic materials

“…Researchers have considered hybridizing different materials with cellulose fibers to produce composite aerogels to improve properties, for instance, cellulose nanocrystals and red mud 47 to improve magnetic conductivity, surface area or spent coffee ground and cotton pads 41 to improve oil adsorption capacity and compressive Young's modulus. Even though the properties of hybrid aerogels normally show significant improvement over non-hybrid aerogels, there is still a gap in the fundamental and theoretical basis of the tunability of interactions between cellulose and other materials.…”