Surface wettability switching of a zeolitic imidazolate framework-deposited membrane for selective efficient oil/water emulsion separation

Oil/water emulsion separation especially for surfactant stabilized emulsions remains a big challenge for environment protection. Membrane separation technology based on special wettable materials is promising for oil/water emulsion separation due to low energy consumption and good separation performance. In this contribution, zeolitic imidazolate framework-8 (ZIF-8) membranes were prepared by vacuum deposition of ZIF-8 particles with different sizes on a regenerated cellulose support. Microparticles gave a better performance as compared to nanoparticles in terms of the permeate flux, while the presence of large interparticle voids adversely affected the rejection efficiency. Such the detriment could be overcome by a sequential deposition of micro particles followed by nanoparticles to form a dense selective layer for oil/water emulsion separation. Hydrophobic modification of pre-formed ZIF-8 particles switched the surface wettability of ZIF-8 deposited membranes from hydrophilic to hydrophobic, offering versatility of the deposited membrane for both oil-in-water and water in-oil emulsion filtration.

Automated summary

Oil/water emulsion separation, especially for surfactant stabilized emulsions, remains a big challenge for environmental protection. Membrane separation technology based on special wettable materials shows promise for this application due to low energy consumption and good separation performance. The study found that sequential deposition of micro particles followed by nanoparticles can form a dense selective layer for efficient oil/water emulsion separation.