Ultralight, highly compressible, hydrophobic and anisotropic lamellar carbon aerogels from graphene/polyvinyl alcohol/cellulose nanofiber aerogel as oil removing absorbents

Abstract

In increasingly serious marine pollution environment, environmentally friendly low-density aerogels have become potential oil-water separation materials. However, many reported aerogels have the drawbacks of low oil absorption, poor compressibility and flexibility, which limit their application. Herein, we reported a compressible, anisotropic lamellar hydrophobic and lipophilic graphene/polyvinyl alcohol/cellulose nanofiber carbon aerogel (a-GPCCA) prepared by directional freeze-drying and carbonization processes. The synthetic ultralight a-GPCCA had low density (6.17 mg/cm3) and high porosity (99.61 %). Moreover, directional freeze-drying resulted in a lamellar interpenetrated three-dimensional porous structure, which endowed it with high adsorption capacity (155–288 times of its weight), good compressibility (95 % recovery after repeating 15 cycles at 50 % strain in parallel to the freezing direction) and recyclability (oil retention rate reached 88.8 % after 10 absorption-compression cycles). Furthermore, carbonization provided it with excellent thermal stability and hydrophobic properties, resulting in oil-water selectivity and combustion cyclicity (the oil absorption capacity was reduced by only 10.2 % after 10 absorption-combustion cycles). Therefore, the a-GPCCA obtained in this study possesses a promising potential in the field of treatment of offshore oil spills and domestic industrial wastewater.