Hydrophobic and oleophilic lauric acid-grafted carbon nanotubes for recyclable efficient oil/water separation

This work demonstrates a novel nanoscale surface modification procedure to enhance the selectivity of multi-walled carbon nanotubes (MWCNTs) in recovering oil from water. Herein, we developed a novel, cost-effective, and facile method to produce highly hydrophobic and superoleophilic lauric acid (LA)-grafted multi-walled carbon nanotubes (MWCNTs-LA) as an absorbent for effective oil spill remediation. The MWCNTs were first oxidized with sodium hydroxide to anchor hydroxyl groups on their surface (MWCNTs-OH) followed by LA grafting via an esterification reaction. Spectroscopic analyses confirmed the grafting of LA onto the MWCNTs' surface, and this treatment made the water contact angle (WCA) of MWCNTs-LA reach 145.26 ± 1.57°, thus showing excellent hydrophobicity and superoleophilicity. The as-prepared absorbent demonstrates good absorption selectivity and absorption capacity of 20.5–33.5 times weight gain for numerous organic solvents and oils. After 5 cycles of absorption-desorption tests, such highly hydrophobic MWCNTs-LA absorbent maintained high oil absorption performance, therefore displaying good reusability and desirable regeneration for practical uses. The MWCNTs-LA absorbent with superb hydrophobicity, superoleophilicity, proper selectivity, and acceptable reusability appears to be promising for the efficient separation and retrieval of spilled oils and organic solvents from water.