Facile fabrication of hydrophilic-underwater superoleophobic poly(N-isopropylacrylamide) coated PP/LPET nonwoven fabrics for highly efficient oil/water separation

Oil/water separation has become an urgent issue in environmental protection. Superhydrophilic and underwater superoleophobic membrane is promising materials for effective oil/water separation. In this paper, a novel oil/water separation nonwoven fabric with robust tensile strength and hydrophilic-underwater superoleophobic is successfully fabricated. This nonwoven fabric using low melt point polyester (LPET) fibers with a unique sheath-core structure to incorporate thermal bonding as reinforcement. Moreover, poly(N-isopropylacrylamide) (PNIPAM) dip-coated is also employed to modify the nonwoven fabrics to acquire the hydrophilic-underwater superoleophobic properties. The mechanical property, microstructure, water and underwater oil contact angle, and oil/water separation properties of PP/LPET nonwoven fabrics are measured, examining the effects of LPET fiber ratio and PNIPAM concentration. The test results show that an improvement in the mechanical properties after increasing the LPET content. The coated of PNIPAM endows the nonwoven fabric with a low water contact angle of from 80° to 0° (within 8 s), and underwater superoleophobicity with a high oil contact angle of 150°. This nonwoven fabric can effective separation oil/water mixture with high permeate flux (∼21850 L∙m−2∙h−1) and high separation efficiency (∼99%), solely driven by gravity. This kind of nonwoven fabrics is suggested as a promising candidate for oil/water separation and water purification.