Morphological features of aerogels and carbogels based on lignosulfonates

Abstract

The synthesis of new carbogels based on sodium lignosulfonates alone (LSNa) and interpolyelectrolyte complexes (IPEC) made by a combination of lignosulfonate and chitosan (CT) (i.e. IPEC-LSNa-CT) was investigated. The IPECs were converted into carbogels by slow and rapid pyrolysis (Pyslow and Pyrapid) and the influence of Py conditions on the formation of carbogels was established. It is demonstrated that the obtained carbogels have a high microporous structure with elevated total porosity values. The porosity of synthesised carbogels is on the nanoscale level, while about 80% of the internal surfaces obtained by both Pyslow and Pyfast is in the range of 0.7–1.0 nm pore size. It was found that elements of the initial precursor structure (LSNa) are stored in the carbon aerogels, if obtained by the appropriate pyrolysis technique.

The effect of synthesis conditions and process parameters on aerogel properties

“…An optimal condition emerged at a 7°C/min heating rate, maximizing the total surface area and pore volume ( Tabrizi and Yavari, 2023 ). In another study, two distinct pyrolysis modes were compared ( Brovko et al, 2017 ). Fast pyrolysis reached 1000°C within 30 min, while slow pyrolysis achieved the same temperature for chitosan-derived carbon aerogels over 15–16 h. The slow mode resulted in pore volume and micropore surface area values that were four and two times greater than the fast mode ( Brovko et al, 2017 ).…”

“…In another study, two distinct pyrolysis modes were compared ( Brovko et al, 2017 ). Fast pyrolysis reached 1000°C within 30 min, while slow pyrolysis achieved the same temperature for chitosan-derived carbon aerogels over 15–16 h. The slow mode resulted in pore volume and micropore surface area values that were four and two times greater than the fast mode ( Brovko et al, 2017 ). The distinction between the two modes lies in the carbonization mechanism.…”

“…This results in minimal changes in morphology. In contrast, slow pyrolysis promotes the diffusion of high-volatile linkers, generating micro- and mesopores within the carbon matrix ( Brovko et al, 2017 ). It should be noted that the pyrolysis mode has received less attention in the literature than carbonization temperature, likely due to the latter’s more pronounced impact on carbon aerogel morphology.…”