Reusable, salt-tolerant and superhydrophilic cellulose hydrogel-coated mesh for efficient gravity-driven oil/water separation

Abstract Oil/water separation has been realized by various materials with special wettability, but most of them require complex instrumentation or involve toxic or corrosive chemicals which may cause potential high cost and environmental concerns. In this work, a superhydrophilic and underwater superoleophobic cellulose hydrogel-coated mesh was fabricated through a simple and green process with the raw materials being low in cost and environmentally benign. The resulting mesh could separate different oil/water mixtures with a separation efficiency higher than 98.9% and a permeate flux up to 12,885 L m−2 h−1 solely driven by gravity. Importantly, this mesh still maintained a separation efficiency >98.2% even after 60 cycles of separation, suggesting its excellent stability for a long term application. Impressively, the mesh also exhibited great anti-salt properties. It was capable to separate saturated NaCl aqueous solutions from their oil (hexane) mixtures with a high separation efficiency. And even immersed in saturated NaCl for 12 h or subjected to sonication treatment, the mesh did not show any worsening in separation properties. These distinct advantages together with the high potential for scale-up production make the mesh very promising toward cost-effective oil/water separation in real-world practice.