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High-Flux Oil/Water Separation with Interfacial Capillary Effect in Switchable Superwetting Cu(OH)₂@ZIF-8 Nanowire Membranes

Li, Qianqian, Deng, Wenjie, Li, Chuanhao, Sun, Qingyun, Huang, Fangzhi, Zhao, Yan, Li, Shikuo
ACS applied materials & interfaces 2018 v.10 no.46 pp. 40265-40273
adsorption, chromium, contact angle, copper, copper nanoparticles, emulsions, ethanol, heavy metals, ions, methylene chloride, nanowires, oils, roughness
Highly ordered architectures with roughness and porous surface are the key challenges toward developing smart superwetting membranes. We prepared switchable superwetting Cu(OH)₂@ZIF-8 core/shell nanowire membranes for high-flux oil/water separation as well as simultaneous heavy-metal ions removal in one step. The well-defined Cu(OH)₂@ZIF-8 core/shell nanowire grown on copper mesh with average length of ca. 15 μm and diameter of ca. 162 nm exhibits high water contact angle (CA) of ca. 153 ± 0.6°. After modified by ethanol, the membrane holds the reverse superwettability with oil (dichloromethane as an example) CA of ca. 155 ± 0.8° underwater. The separation efficiencies of the membranes are higher than that of 97.2% with a remarkable flux rate higher than 90 000 L m–² h–¹ for the immiscible oil/water mixture. And the removal efficiency for Cr³⁺ ions at 10 ppb can arrive at 99.2 wt % in the toluene-in-water emulsion. The high performances of the smart superwetting membranes can be attributed to the interfacial capillary effects of the hierarchical Cu(OH)₂@ZIF-8 core/shell nanostructures. This work may provide a new insight into the design of smart superwetting surfaces for oil/water separation and target adsorption in one step.