Sustainable Cross-Linkers for the Synthesis of Cellulose-Based Aerogels: Research and Application

Abstract

Cellulose aerogels with polyester resin as cross-linkers have attracted much attention. This study describes the route to produce a fully bio-based aerogel with high added value from waste paper and starch, cellulose acetate and starch–cellulose acetate mixture as cross-linkers for oil adsorption, instead of the environmentally harmful polyester resin. The manufacturing process is simple, sustainable and cost-efficient, without releasing harmful by-products into the environment. The effects of different cross-linkers on the oil adsorption, dynamic oil retention, reusability and morphology of the aerogels were studied in detail. Experimental results show that these environmentally friendly recycled aerogels have a very low density, i.e., —0.0110–0.0209 g cm−3, and highly porous structures, with a porosity of 96.74–99.18%. The synthesized hydrophobic aerogels showed contact angles of ∼124–129°. The compression moduli are lower than that of an aerogel with polyester as a cross-linker, but the compression modulus of the mixture of starch and cellulose acetate especially shows a higher value than expected. The sorption capacity of the aerogels with bio-based cross-linkers was significantly increased compared to the aerogels with polyester; it is now up to 56 times their own weight. The aerogels also have good oil-retention properties.

Mechanical Properties of Cellulose Aerogel Composites with and without Crude Oil Filling

“…The production of the cellulose aerogel samples used in this study from cardboard paper-waste and starch and partly with and without hemp fibers is described in [14]. Information about the structure and morphology of the cellulose aerogels can be found in [35]. A total of 250 samples of different compositions were produced, so every measurement was repeated 5 times.…”

Insights into sustainable aerogels from lignocellulosic materials

“…In one study, cellulose aerogels were prepared with four different cross-linkers with cellulose to synthesize aerogels, including polyester resin, cellulose acetate, starch, and a mixture of starch and cellulose acetate. 84 The results show that the density of aerogel samples with different cross-linkers is in the order of polyester resin > starch > start-cellulose acetate > cellulose acetate. The compression modulus can be linearly proportional to the density.…”

“…Based on literature survey, the number of comparative studies of different cross-linking agents on performance or properties of aerogels is very limited. In one study cellulose aerogels were prepared with four different cross-linkers with cellulose to synthesize aerogels, including polyester resin, cellulose acetate, starch, and a mixture of starch and cellulose acetate 84 . The results show that density of aerogel samples with different cross-linkers is in the order:…”

“…Because porosity decreases with increasing density, the compression moduli is inversely proportional to the porosity. Oil adsorption of aerogels is a physical phenomenon depending on the porosity, the oil adsorption capacity is thus increasing with the increase of porosity 84 . In another study, Loh et al investigated the effects of crosslinker (PVA) concentration on properties of aerogels from waste wool 62 .…”

“…Oil adsorption of aerogels is a physical phenomenon depending on the porosity, the oil adsorption capacity thus increases with the increase of porosity. 84 In another study, Loh et al investigated the effects of cross-linker (PVA) concentration on the properties of aerogels from waste wool. 62 The results show that increasing either PVA or cellulose will increase the density of aerogels, effectively decreasing the porosity, which in turn reduces the oil adsorption capacity.…”