Reusable superhydrophobic fluorinated cellulose-graphene composite aerogels for selective oil absorption

Abstract

Although some progress had been made in the adsorption of graphene aerogels, more research was needed on their elasticity and recyclability. In this paper, a superhydrophobic fluorinated cellulose and graphene composite aerogel (FCGA) was prepared by a simple two-step impregnation method. Firstly, nano-cellulose was introduced into the graphene aerogel to inhibit the excessive accumulation of graphene lamellae and increase the specific surface area. The surface of the composite aerogel was then impregnated with silanol and fluorinated functional groups by a two-step impregnation method, resulting in a superhydrophobic aerogel with remarkable elasticity. The introduction of cellulose and silane provided the aerogel with excellent elasticity and recovery from cyclic adsorption. The successful grafting of the fluorophobic groups of PFDMS onto the graphene oxide strengthened the framework of the graphene aerogel, making FCGA a good candidate for repeated selective oil absorption. It could be restored to the original height after compression to 50% and 80% strain decompression. FCGA could efficiently absorb oil in water and had a high organic adsorption capacity. And the adsorption capacity of different oils/organic solvents reached 22,480 mg/g∼36,700 mg/g. Its absorption efficiency remained above 98.5% under distillation cycles. Due to its high elasticity, it retained more than 90% of its cyclic adsorption capacity through the squeeze cycle. As a simple, low-cost recovery method, its reusability was already better than most known adsorption elastic materials. The prepared composite aerogel had the advantages of simple preparation, low density (0.014 g/cm3), superhydrophobicity (water contact angle 153.3°), excellent adsorption properties, and recyclability. Therefore, FCGA had a very promising application in circulating selective oil absorption.