Choline chloride/urea etched carbon fiber to improve the elasticity of biomass-based carbon aerogel for efficient oil-water separation

Abstract

Carbon aerogel prepared using waste biomass as the carbon source can be utilized as the ideal absorption material for the remediation of oil spill accidents. However, the brittleness of the fiber and agglomeration of precursor fiber chains due to hydrogen bonding leads to poor mechanical properties and low absorption capacity of the carbon aerogel. The doping treatment used to overcome such defects still shows some deficiencies, such as high cost, cumbersome process, and part of the process involving toxicity. To overcome the agglomeration between the cellulose chains, a chemically-etched biomass-based carbon aerogel (EBCA) was prepared using pineapple cellulose nanofiber (CNF) etched by the deep eutectic solvents (DES) of choline chloride/urea under a low carbonization temperature of 400 °C. The as-prepared material, designated as EBCA-400, possesses a 3D structure with a huge BET specific surface area of 501.56 m2 g−1, a density of only 0.032 g cm−3 and a porosity of 97.3% with excellent elasticity performance and self-recovery performance owing to the enhancement of the surface roughness of fibers through DES etching. Also, EBCA-400 shows a superhydrophobicity with a water contact angle (WCA) of 157.6° and has a strong and fast absorption capacity for various oils in various scenarios, the absorption capacity for CCl4 reaches 288 times its own weight, and the absorption efficiency to CCl4 can still reach more than 97% of the maximum value even after 15 oil absorption-removal cycles. With the characteristics of very low density, huge porosity, excellent elasticity and superhydrophobicity as well as better reusability, EBCA-400 has great potential in oil spill remediation. This study provides a convenient and environment-friendly way for surface modification to improve the elasticity of carbon aerogel, which is crucial to the recovery of carbon aerogel for its reusability.