Super-elastic compressible chitosan/chlorella pyrenoidosa-graphene biomass aerogel with accordion-like structure for all-weather and high-efficiency cleanup of crude oil spills

Abstract

Crude oil spills represent a major environmental catastrophe in marine ecosystems. The high viscosity of crude oil significantly hampers its ability to infiltrate traditional porous adsorbent materials. Fortunately, the viscosity of crude oil is highly sensitive to temperature. In this work, a self-heated aerogel, powered by both solar and Joule heating, was designed as an all-weather adsorbent for continuous crude oil absorption by markedly reducing its viscosity. The chitosan (CS)/chlorella pyrenoidosa (CP)-Graphene (GO) biomass aerogel featuring an accordion-like structure and super-elastic compressible, was first fabricated using a directional freeze casting technique. It was then subjected to surface treatment with GO/carbon nanotube (CNTs) and methyltrimethoxysilane (MTMS) to impart Joule heating effects and hydrophobicity, respectively (named H-CS/CP-G). The special accordion-like structure endows it with excellent mechanical properties, the height recovery rate of the H-CS/CP-G biomass aerogel can reach 95 % after 10 cyclic compression experiments. The H-CS/CP-G biomass aerogel can rapidly attain 79.4 °C under one sun exposure, and similarly, it can quickly heat up to 79.6 °C when a 6 V voltage is applied. This temperature responsiveness enables efficient all-weather cleanup of crude oil. More importantly, the H-CS/CP-G biomass aerogel is capable of absorbing crude oil up to 25 times its own weight and possesses a recyclability of 90.7 % after 10 absorption-extrusion cycles. When integrated with a vacuum pump system, the biomass aerogel facilitates the continuous extraction of crude oil from the water surface. Therefore, through the synergistic effect of photothermal and Joule heating, along with the construction of a unique accordion-like structure, the H-CS/CP-G aerogel, with the assistance of a pump absorption device, can achieve efficient and continuous separation of high-viscosity crude oil in all weather conditions. The prepared all-weather biomass aerogel, with low cost, easy preparation, environmental friendliness, and high efficiency, offers a sustainable and effective solution for the cleanup of crude oil spills.