Influence of the addition of carbon structures in cellulose cryogels

The substitution of carbon structures, such as graphene and carbon nanotubes by biochar, is interesting, since the latter has considerably lower costs and similar properties to other structures. Therefore, the objective of the present paper was to evaluate the influence of the addition of biochar (BC), produced from the pyrolysis of cellulose residues, in order to substitute graphene nanoplatelets (GNP), regarding the thermal, mechanical and adsorption aspects. The cryogels were produced from the cellulose suspension with the addition of 50 and 100 (% w/w in relation to cellulose) of BC or GNP. Extremely light cryogels (with apparent density less than 0.033 g cm−3 and porosity greater than 90%) were produced. The addition of BC and GNP showed similar values in terms of compressive strength, temperature of degradation and thermal conductivity. In the heterogeneous adsorption capacity, however, a significant difference was observed between the two carbon structures studied, and for this property, the GNPs showed a slight increase in the adsorption capacity in relation to BC. In the general context of the properties studied, the biochar has the potential to be used to replace commercially used carbon structures, such as graphene nanoplatelets.