Zirconium diboride assisted superhydrophobic/superoleophilic surface modification of polyurethane sponge for continuous oil-water separation and emulsion purification

Background: With rapid industrialization, water pollution by accidental oil spills and industrial wastes dumping into water bodies has become a severe threat to the marine ecosystem. In this regard, usage of superhydrophobic/superoleophilic sorbent is forecasted perhaps one of the best solution to recover oil and natural solvents from contaminated water owing to its high absorption capacity, and recyclability. Methods: Herein, we report zirconium diboride modified polyurethane sponge (ZrB2@PUS) prepared by facile dip coating technique at ambient condition for selective oil/water removal. The ZrB2@PUS was further functionalized using octadecyl trichlorosilane (OTS) in presence of toluene to impart superhydrophobicity. Significant findings: Microstructural analysis revealed that ZrB2 platelets anchored onto smooth struts of PUS thereby increasing surface roughness, whereas, OTS helps in decreasing the surface tension and enhancing the non-wettability. The ZrB2@PUS exhibited a contact angle -166 degrees and -0 degrees for a sessile water and oil droplet, respectively. Moreover, ZrB2@PUS was found suitable for removal of various oil and organic solvents from oilwater mixture with absorption capacity reaching -83-129 g/g and capacity retention -92-97% after 20 cycles in static and dynamic conditions. OTS-functionalized ZrB2@PUS also successfully explored for separating SDS stabilized diesel-in-water and toluene-in-water emulsion, demonstrating feasibility for wastewater treatment containing oil and organic solvents.

Automated summary

This study presents the development of a zirconium diboride modified polyurethane sponge, prepared through a dip coating technique and functionalized with octadecyl trichlorosilane for superhydrophobicity. The sponge shows great potential in removing oil/water, oil-water mixtures, and wastewater containing oil and organic solvents.