Ambient pressure dried, light-weight and superelastic aramid nanofibers/graphene composite aerogels for fast adsorption of viscous oils

Abstract

Fabrication of high-performance aerogels based on dissociated aramid nanofibers (DANF) is one of important ways for reusing the waste aramid fibers. However, the highly energy-intensive drying techniques and suboptimal performance hinder their large-scale production and practical applications. Here, a simple assembly and modification process based on the ambient pressure drying (APD) method with low energy consumption is developed to prepare high-performance aerogels using DANF and reduced graphene oxide (RGO). The DANF aerogel prepared by APD exhibit a lower density (low to 28 mg/cm³, reduced by 52 %) and better elasticity compared to that assembled by polymerized aramid nanofibers (PANF). This can be attributed to the larger and more robust pore walls formed by DANF. The DANF aerogel demonstrates stable elasticity even at ultralow temperatures (−196 ℃) and wide frequencies. Furthermore, it exhibits a low thermal conductivity (0.03 W/(m*K)) and high temperature insulation rate (∼70 %, 10 mm, 300 ℃). The modified DANF/RGO aerogels with high hydrophobicity (138°), and excellent solar-thermal and electrical-thermal conversion properties can absorb highly viscous oils, much faster than DANF aerogels. More importantly, they are easily recyclable through the extrusion or distillation ways due to their exceptional elasticity and thermostability. This study presents a low-energy-consumption approach for the high-value reutilization of waste aramid fibers.