Multifunctional carbon/biomass composite aerogel with a layered structure for efficient solar-driven high-viscous oily seawater purification

Abstract

High-viscosity crude oil spills on seawater surfaces are among the most challenging marine environmental disasters due to their recovery difficulties. Additionally, soluble organic pollutants within the oil phase can easily enter aquatic systems. This underscores the urgent need for bifunctional materials capable of mitigating the environmental hazards of oil spills in complex scenarios. In this study, we present a superhydrophobic, bifunctional chitosan-based aerogel featuring a tree-like, multi-layered hierarchical structure, fabricated via the directional freeze-casting technique. This aerogel, referred to as GC@CS, is designed to enhance crude oil recovery while simultaneously addressing the removal of soluble pollutants. Hydrothermally carbonated carbon (HTCC), valued for its exceptional photothermal conversion and photocatalytic properties, was incorporated into the aerogel. Additionally, graphene was integrated to enhance light absorption and vertical heat transfer efficiency. We systematically investigated how variations in sunlight intensity and aerogel pore structure affect oil adsorption rates and the degradation of GC@CS with different organic dyes. Importantly, GC@CS efficiently degrades soluble dyes, representing organic pollutants in water, through an adsorption-photocatalysis process. Notably, the GC@CS aerogel is biodegradable and does not cause secondary environmental pollution. The novel chitosan-based aerogel GC@CS shows significant potential for broad applications in oil spill remediation and environmental cleanup.