Photothermal-driven bio-based composite sponge for sustainable oil-water separation: A green strategy utilising...

With the increasing frequency of offshore oil spills and oily wastewater discharges, there is an urgent need to develop efficient and sustainable materials for oil-water separation. Although aerogels possess high porosity and adsorption capacity, traditional materials face challenges such as brittleness, complex synthesis, and poor environmental compatibility. In this study, a photothermal-driven bio-based composite sponge (LS/MVCCS) was constructed using a biomimetic "steel-concrete" strategy, based on a natural loofah sponge (LS) skeleton combined with vanillin-crosslinked chitosan (CS) and carbon nanotubes (CNTs). The material features a multi-level pore structure and excellent superhydrophobicity (water contact angle of 150.3^o), exhibiting high adsorption capacity (up to 40.79 g/g) for various oils and organic solvents, along with mechanical stability (The height retention rate after ten compressions is 98.5%). Furthermore, the incorporation of CNTs provided significant photothermal conversion capability, enabling the material to heat up to 68.4 °C within 4 min under 1.0 kW/m² irradiation, effectively reducing the viscosity of high-viscosity oils and enhancing recovery efficiency. The results demonstrate that the LS/MVCCS composite sponge achieves highly efficient separation (>99.5% efficiency) in gravity-driven filtration, vacuum suction, and emulsion separation scenarios, offering a new approach for developing green and recyclable materials for oil spill treatment.