Synergistic assembly of micro-islands by lignin and dopamine for superhydrophobic surface: Preparative chemistry and oil/water separation performance

Superhydrophobic oil-water separation substrates with low cost, high quality and highly efficient performance are desirable in practical fields; however, utilizing the synergistic chemistry of intrinsic molecular characters of lignin (HTL) and dopamine (DA) was rarely reported, even both of which extensively studied for fabricating varied functional materials. Here, inspired by mussel chemistry, superhydrophobic melamine foam (MF) composites with stable micro-islands projections were constructed ([email protected]) by free radical addition of dopamine (DA) and hydrothermal extraction of β-O-4 bond-rich lignin (HTL) as a primer and installation of an auxiliary coating silicon coating (SC). In a certain area, MF formed porous network channels supplying space for oil absorption, while the slender MF fiber acted as a "temporary antenna" to adsorb the wee oil droplets in oily wastewater, ensuring efficient oil/water separation for oil/water mixture (98% after 10 cycles) and achieving strong adsorption capacity (57.48–147.33 g/g). Several technology-model-supported experiments presented that the [email protected] superhydrophobic material with micro-island projections maintained greatly mechanical stability and apparent contact angle considerable to withstand 10 friction and tape stripping cycles. Even being treated by different pH environments, as-designed superhydrophobic surface still maintained a water contact angle beyond 150°, favorably confirming its acid and alkali resistance under testing conditions.