Superhydrophobic ZIF-67 sponge: A breakthrough in efficient oil-water separation

The hydrophobic long-chain coupling agent, γ-aminopropyltriethoxysilane (KH550), was selected for the modification of ZIF-67 to create hydrophobic imidazole metal-organic frameworks (MOFs) composites, designated as SA/ZIF. The study reveals that the modified SA/ZIF exhibits substantial enhancement in surface wettability, achieving a water contact angle (WCA) of 123.2 ± 2°, in stark contrast to the original ZIF-67, which displayed a WCA of 0°. Additionally, the research involved coating an in-situ synthesized ZIF/MS sponge with a KH550 hydrophobic emulsion through dip-coating to enhance surface roughness and reduce surface energy, successfully creating hydrophobic SA/ZIF/MS sponge composites. This material exhibits excellent water resistance, with a WCA of 157.6 ± 2°, effectively separates oil/water mixtures with a separation efficiency of 99 %, and results in a filtrate with a water content of <10 ppm after separation. Furthermore, the material shows outstanding adsorption capacity for eight different oils and organic solvents, ranging from 54.1 g/g to 140.1 g/g. The article also details the synthesis, characterization, and performance of the material in oil-water separation applications.