Construction of superhydrophobic ZIF-90/Melamine sponge with highly stable puncture structure for sustainable oil spill removal from seawater

Abstract

Sustainable, environmentally friendly and economically viable treatment of marine oil spills attracts a great attention. For the first time, composites with highly durable structure were prepared for continuous oil/water separation by in situ growth of zeolitic imidazole framework ZIF-90 on a porous melamine sponge (MS). First, a thin layer of metal hydroxide (Zn-LDH) was introduced on the inner wall of MS and ZIF-90 particles were loaded onto the sponge fibers by homologous induction to obtain the ZIF-90/MS composite. The thin Zn-LDH layer greatly enhanced the anchoring force of ZIF-90 on the MS skeleton to effectively avoid the crystals from piling up together. The resulting ZIF-90/MS was modified in situ with octadecylamine (ODA) to give a superhydrophobic ODA-ZIF-90/MS composite with a water contact angle (WCA) of 154o, which demonstrated great oil adsorption capacity (24–63 g/g) and excellent recoverability (98.7% absorption retention after 50 cycles). With the assistance of a pump drive, continuous separation of oil spill contaminants from actual seawater can be achieved with fluxes of 13839 g. h−1. g−1 and 13513 g. h−1. g−1 for hexane and gasoline, respectively, without any water adsorption. The highly durable ODA-ZIF-90/MS composite with puncture structure showed excellent cycling performance in oil/water separation with less than 1% ODA-ZIF-90 spillage after 50 squeeze desorption cycles. This novel integrated ODA-ZIF-90/MS composite demonstrates a promising strategy for large-scale of oil spill cleanup.