Recent advances in carbon nanotube sponge-based sorption technologies for mitigation of marine oil spills

Oil spills stemming from supertankers, drilling, and natural events represent a serious problem worldwide due to the potential harms to marine ecosystems and aquatic life. To date, various functional absorbents have been developed to treat spilled oil. Among them, carbon nanotube (CNT)-based aerogels and sponges gained attention due to superior performance in uptake and recovery of various types of oil and organic solvents. CNT aerogel/sponge absorbents are demonstrated for a multitude of merits such as: rapid superhydrophobic/superoleophilic absorption (water contact angle > 150°), high capacity (≥100 mg g^-1), large surface area (300-400 m² g^-1)), enhanced strength and flexibility (>95% volume reduction and restoration of pristine morphology at <0.25 MPa stress), mesoporous characteristics with high pore density (pore diameter = 80 nm and >99% porosity), recyclability, and easy surface modification.

This review compares CNT sponge-based absorbents with conventional techniques for remediation/recovery of spilled oil. Typically, synthesis of CNT sponges is performed using chemical vapor deposition (CVD) approach in the presence of a catalyst or using sacrificial removal of template. This work summarizes recent progress in strategies for oil-spill treatment based on CNT sponge techniques. The performance of CNT sponges for oil spill removal was evaluated in terms of their adsorption capacity, compressive stressability, and desorption methods (e.g., heat treatment, burning, or squeezing).

CNT sponges were observed to have high performance for removal of oil spills in terms of key performance metrics. This review offers valuable insights into the current state of CNT-mediated oil-spill cleanup technologies and guidance for future research at the same time. This literature survey would help the stakeholders (researchers, scientists, entrepreneurs, and commercial houses) pursue contamination-free water.