Superhydrophobic melamine sponges with high performance in oil/organic solvent sorption

Abstract

The severe adverse impacts of the frequently occurring marine oil spills call for the urgent development of an efficient approach for oil spill restoration. Here, we prepared a superhydrophobic melamine sponge with water contact angle of 151.6° via a one-step dip-coating process by simply reacting the melamine sponge with stearic anhydride. The as-prepared sponge, MS-4, demonstrates excellent sorption capacities for various organic solvents such as hexane, toluene and chloroform, as well as oils including diesel, mineral oil, and crude oil, with sorption capacities ranging from 78 to 160 times its own mass. Moreover, MS-4 exhibits good recyclability with retention rate of over 93% even after 50 sorption/squeezing cycles, remarkable stability when exposed to challenging conditions such as strong acidic (pH = 1.0) and alkaline (pH = 13.0) environments, as well as high salinity environments. Additionally, MS-4 displays superb selectivity, enabling the continuous oil/water separation when assisted by a vacuum pump, achieving a high flux of approximately 106 L•m−2•h−1, while maintaining a low water content of as minimal as 30 ppm. Notably, through a facile filtration process, MS-4 achieves an exceptional demulsification efficiency of up to 99.7% for water-in-oil emulsions.