Superhydrophobic sponges based on green deep eutectic solvents for spill oil removal from water

The paper described a new method for crude oil-water separation by means of superhydrophobic melamine sponges impregnated by deep eutectic solvents (MS-DES). Due to the numerous potential of two-component DES formation, simple and quick screening of 156 non-ionic deep eutectic solvents using COSMO-RS (Conductor-like Screening Model for Real Solvents) computational model was used. DES which were characterized by high solubility of hydrocarbons and the lowest water solubility were synthesized and embedded on melamine sponges. The new sponges were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and goniometer. Several parameters affecting the crude oil-water separation (i.e. type and amount of DES, density and porosity of sponges, water contact eagle) were thoroughly studied. In order to studies of MS-DES affinity to the selected groups of crude oil i.e. Saturated, Aromatic, Resins, Asphaltenes (SARA) the thin layer liquid chromatography-flame ionization detection (TLC-FID) was used. The obtained results indicate that the melamine sponges impregnated by DES composed of eucalyptol and menthol in 1:5 molar ratio have high real crude oil absorption capacity in the range of 96.1 - 132.2 g/g and slightly depends on crude oil compositions, superhydrophobic properties (water contact angle 152°), low density of 9.23 mg/cm³, high porosity of 99.39%, and excellent reusability which was almost not changing even after 80 cycles. The outcomes indicate that new MS-DES materials could be excellent alternatives as absorbents for the cleanup of crude oil-polluted water.