Development of a superhydrophobic and superoleophilic halloysite nanotube/phenyltriethoxysilane-coated melamine sponge sorbent material with high performance in supercritical CO2 atmosphere for the selective and effective oil spill cleanup and oil-water separation

In this study, activated halloysite nanotube (HNT) and phenyltriethoxysilane (PTES) were utilized for the first time to fabricate modified HNT materials and coat them onto melamine sponge (MS) substrate in the supercritical carbon dioxide (scCO2) atmosphere. The successful coating of MS substrate was confirmed using SEM, EDS, XPS, and contact angle measurements. The drainage technique applied in the CO2 medium achieved the uniform coating of both the inner and outer surfaces of the MS. Water and oil contact angles of the fabricated sorbent material (MS-PTES) were measured as 167.1 degrees and 0 degrees, respectively. MS-PTES sorbent having superhydrophobic and superoleophilic properties demonstrated sorption capacities ranging from 47.6 g/g to 132.2 g/g for 13 different pollutants, including various petroleum products, oils, and organic solvents. Moreover, the MSPTES sorbent material showed outstanding separation efficiency (99.99%) for the diesel-water mixture using a continuous separation process. It also displayed high selectivity for oil and organic solvent pollutants under acidic, saline, and alkaline conditions, along with excellent reusability, chemical stability, robustness, and mechanical flexibility. MS sorbent material coated with HNT-modified PTES nanoparticles, produced in the scCO2 atmosphere using the drainage technique, represents a promising solution for the removal of petroleum derivatives, oils, and organic solvents from water.