Superhydrophobic and superoleophilic melamine sponges impregnated with deep eutectic solvents for oil spill cleanup

Abstract

The extensive extraction of oil from the bottom of seas and oceans and its transportation by tankers increase the risk of potential environmental disasters associated with hydrocarbon fractions entering water reservoirs. Therefore, this paper presents the preparation of a simple impregnation of a melamine sponge with deep eutectic solvents (DES), which can be obtained from natural sources, including coconut oil, palm kernel oil, seed oils, mammalian milk, and substances commonly used in pharmacological and physiological studies. A preselection method based on the COSMO-RS model was used to select the most suitable DES among 760 solvents. The selected DES were prepared and impregnated on melamine sponge (MS). Structural and surface analyses were performed by DES-MS. The process parameters that affect the sorption capacity of DES-MS and the affinity tests were performed for specific oil groups. The highest absorption capacities were obtained for MS impregnated with tetraethylammonium chloride and decanoic acid in a 1:2 M ratio. The prepared new DES-MS were characterized by very high sorption capacities ranging from 40.9 to 99.8 g/g, as well as superhydrophobicity (water contact angle 151°), superoleophobicity (oil contact angle 0°), low density (0.177 g/cm3), high porosity (88.25 %), high thermal, mechanical, and chemical stability, and the possibility of multiple regenerations without loss of sorption capacity. In addition, the preparation of DES-MS is simple and involves little time and consumption of toxic organic solvents. These results indicate that DES-MS may be a “green” and low-cost alternative to current approaches for removing oil from water.