Synthesis of elastic hydrophobic biomass sponge for rapid solar-driven viscous crude-oil cleanup absorption, oil-water separation and organic pollutants treating

Oil spills pose a global challenge for environmental remediation and the high viscosity of crude oil makes conventional sorbents ineffective for complete remediation. Inspired by the solar energy-motivated viscosity-break, a photothermal three-dimensional (3D) polydimethylsiloxane modified CuS-loaded biomass-derived carbon fibers/reduced graphene sponge (PDMS/CuS/CFs/RGO) was synthesized using self-assembly, carbonization, freeze-drying, and hydrophobic modification methods that utilize natural renewable resources in an efficient manner. By using infrared thermal imaging, oil droplet permeability behavior, and oil absorption-recovery, we studied the photothermal effect of adsorbents on oil absorption. Based on the results, the PDMS/CuS/CFs/RGO sponge demonstrated excellent photothermal conversion ability and stability with almost full solar absorption. Under 0.3-sun simulated irradiation (0.3 kW/m2) at room temperature, the surface temperature spontaneously increased to 75.9 °C, which reduced the in-situ viscosity of crude oil and significantly increased its diffusion coefficient and adsorption rate. Consequently, the PDMS/CuS/CFs/RGO sponge exhibited excellent oil cleaning absorption rates up to 66.8 times their weight and outstanding recyclability. Additionally, the sponge showed excellent adsorption capabilities for organic solvents and low viscosity oils (13.8–26.1 g/g). Notably, the PDMS/CuS/CFs/RGO sponge was able to achieve dye degradation due to its photocatalytic property. Combined with comprehensive functions including rapid solar-driven viscous crude-oil cleanup absorption, oil/water separation, and photocatalytic property, the bio-based PDMS/CuS/CFs/RGO sponge has great application prospects in water remediation, especially in the treatment of contaminated water with complex components.