Superhydrophobic and superoleophilic polyurethane: Effect of different sponge densities, magnesium stearate loadings, harsh environmental conditions

Referring to catastrophic damages of oil and organic pollution leakage to the aquatic environment, providing a high efficiency technique for the oil-water separation becomes a hot research topic during the recent decade. This study focused on effects of the sponge density and magnesium stearate loadings on the separation performance of superhydrophobic magnesium stearate coated-polyurethane. The sponges with three densities of 8, 13, and 18 kg m(-3) were coated with different magnesium stearate loadings of 5 and 10 wt% by dip-coating method. A set of various analyzes, including field-emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), contact angle, absorption rate and capacity, continuous oil-water separation, were conducted in neutral, acidic, and basic conditions. FESEM results demonstrated the sponges became increasingly rough after coating with magnesium stearate. The wettability measurements revealed the sponge density had no significant impacts on the water contact angle, all samples presenting around 175 degrees +/- 2 degrees and oil absorption rate less than 1 s. Finally, the absorption capacity of the unmodified and modified sponges for treating various oils and solvents demonstrated that the coated spongy could absorb a wide range of oils and organic solvents with capacity range of 15-75 times their weight, depending on the different densities and loadings.

Automated summary

This study focused on the effects of sponge density and magnesium stearate loadings on the separation performance of superhydrophobic magnesium stearate coated-polyurethane. The results showed that the surface of the sponge became rougher after being coated with magnesium stearate, while the sponge density had no significant impact on the water contact angle and oil absorption rate. The absorption capacity of the modified sponges for various oils and solvents was also tested and showed promising results.