Features and Consequences of Isopropanol Burning off PTFE-rGO Aerogels

An improved procedure for the preparation of aerogel granules of polytetrafluoroethylene-graphene oxide (PTFE-GO) with a composition of 50:50 (in wt %) and a specific density of 35 ± 2 mg/cm³ is described. The technique practically excludes the granule cracking. The specific density of the pellets after reduction using hydrazine vapor and annealing at 370 °C decreased to 29 ± 2 mg/cm³. The PTFE-reduced GO (rGO) pellets obtained were tested as a recyclable sorbent for isopropyl alcohol (IPA) in sorption/combustion cycles. It has been shown that the aerogel sorption capacity for IPA increases from 35.6 to 39.3 g/g as a result of alcohol burning off. During the combustion of IPA, the temperature of an individual pellet can exceed 300 °C. When several contingent pellets are burned, the temperature of their heating increases. The fine-pored structure of the near-surface layer of the granule is destroyed during the alcohol burning, the internal structure with larger pores is exposed, and the relative proportion of PTFE on the surface of the granules decreases. It was also shown that the specific surface area of PTFE-rGO increases from 26 to 49 m²/g during cycling.