Micro-/nano architectures in MOF membrane accelerate oil-water separation
Frequent oil spills during oil transportation have become a critical global environmental and economic problem. Traditional oil-water separation technologies, including centrifugation, filtration, dissolved air flotation, oil skimmers and adsorption, have low efficiency and consume large amounts of energy during complex separation processes.
Membrane separation is a promising and economical approach to tackle energy and environmental challenges. Inspired by the anti-wetting behavior of an oil droplet on fish scales in water, researchers have developed underwater superoleophobic materials in recent years. However, some organic polymer membranes lose oil-water separation capacity at high temperature or exposure to organic solvents. Additionally, producing most inorganic membranes entails complex preparation processes.
In order to solve these problems, Ming Xue and co-workers from Jilin University, China, have introduced a micro/nanostructure into a MOF membrane to improve the water/oil separation efficiency. Their results are published in Science China Materials.
This MOF membrane exhibits excellent separation efficiency over 99.99 percent for various oil-water mixtures with the residual oil content in the collected water less than 4 ppm. It also shows a remarkable water flux as high as 10,2000 L/m2h and higher oil intrusion pressure of 6400 Pa. Regarding stability, Xue said, "this membrane displays outstanding stability under high temperature (200°C) and when exposed to various organic solvents (tetrahydrofuran (THF), N, N'-dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), dichloromethane (DCM) and n-hexane) immersion."
"More importantly," he added, "based on its facile fabrication method and the readily available and cheap materials, this kind of MOF membrane can be easily enlarged, and able to treat a large amount of oil-water mixture."