Self-heating, elastic, hydrophobic wood sponge for recovering spilled crude oil under sunlight and microwave dual stimuli

Water pollution caused by crude oil spills poses significant environmental concerns. In this work, multi-walled carbon nanotubes (MWCNTs) were dispersed as the carbon network on the elastic wood sponge (WS) and then encapsulated by hydrophobic polydimethylsiloxane (PDMS) coating to form a crude oil adsorbent, PDMS@CNT-WS. It demonstrated an elasticity of up to 90% compressive strain, while the height retention remained at 97% even after 100 cycles at 50% compressive strain. The shape-memory properties and 148°hydrophobic angle of the material allowed it to be repeatedly used. This is the first material to utilize sunlight and microwave as dual stimuli to absorb and recover spilled crude oil. PDMS@CNT-WS absorbed crude oil floating on water within about 80 s under 1 sun illumination. After condensation, the material was heated within only 4 s in a microwave oven at 2450 MHz, and the crude oil in the interior could be recovered by simply squeezing the material. This new approach provided a source of energy conversion for crude oil adsorbents with thermal management capabilities to clean up crude oil spills.